Herbs & Botanicals · Herbs · unroasted coffee seed, chlorogenic acid and caffeine, weight-loss supplement, small trials

Green Coffee Bean Extract

Q: What is green coffee bean extract?

It is an extract of unroasted coffee seeds from Coffea arabica or C. canephora, rich in chlorogenic acids. Many products also contain caffeine unless labelled decaffeinated.

Q: Does green coffee extract help you lose weight?

Pooled small trials show average weight losses of about 1 to 2.5 kg in favourable analyses, and one large analysis found no significant weight change. Reviewers call the trials few, short and often poor quality.

Q: What happened to the famous green coffee weight-loss study?

A 2012 trial that reported large weight loss was retracted in 2014. The FTC said the study was so flawed no reliable conclusions could be drawn, and the company that sold the extract settled for $3.5 million.

Q: Does it lower blood pressure?

A 2024 pooled analysis of 10 studies found about 3 mmHg lower systolic and 2 mmHg lower diastolic pressure. The trials are small and several were funded by chlorogenic acid makers. Caffeine can raise blood pressure in some people.

Q: Does it help with blood sugar or diabetes?

Fasting glucose was only about 2 mg/dL lower in pooled data and HbA1c did not change. No trial in people with diagnosed diabetes was found. Ask your doctor or pharmacist if you take diabetes medicine.

Q: How much caffeine is in it?

The sources we read do not give a caffeine amount for green coffee products. Check the label. EFSA says up to 400 mg a day from all sources is not a concern for healthy adults.

Q: Can it harm the liver?

A case series linked fat-burner supplements that included green coffee beans, green tea extract, Garcinia and spirulina to liver injury, with one liver transplant. Green coffee could not be singled out. No LiverTox entry for green coffee was found.

Q: Does it interact with medicines?

Mostly through caffeine. RxList lists interactions with drugs that slow caffeine breakdown, other stimulants, lithium, blood thinners (theory), diabetes drugs and blood pressure drugs. These are mostly theory, not green coffee trials. Ask your pharmacist.

Q: Does it affect iron?

Coffee polyphenols reduced non-haem iron absorption in a meal study with brewed drinks. This has not been studied with the extract. If you are low in iron, ask your doctor or pharmacist about timing.

Q: Is it safe in pregnancy or breastfeeding?

RxList advises avoiding it because reliable information is insufficient. EFSA says up to 200 mg of caffeine a day from all sources is not a concern for the foetus; the extract itself was not studied in pregnancy.

Coffea arabica L. and Coffea canephora Pierre ex A.Froehner · also called green coffee, green coffee extract, unroasted coffee, GCE, robusta (C. canephora)

Green coffee bean extract comes from unroasted coffee seeds. It is rich in chlorogenic acids and often contains caffeine. It is sold for weight loss and blood pressure. Pooled studies show small changes, the most famous weight-loss trial was retracted, and caffeine and rare liver reports need care.

General information, not medical advice. Last substantive update October 25, 2026 · Not medically reviewed. A named clinician has not signed off on this page. How this page is made

About Green Coffee Bean Extract

Green coffee bean extract comes from the unroasted seeds of Coffea arabica and C. canephora. Its best-known compound is chlorogenic acid, and many products also contain caffeine. Pooled trials show small average changes in weight and blood pressure, but the trials are few, short and sometimes industry-funded. The 2012 weight-loss trial that made it famous was retracted. Safety points are caffeine, drug interactions, lower iron absorption and liver injury reports with multi-ingredient fat burners.

What it is

Green coffee is the raw, unroasted seed of the coffee plant. GBIF lists both Coffea arabica L. and Coffea canephora (robusta) as accepted species in the coffee family, Rubiaceae. Extracts are standardised for chlorogenic acids, and some are sold decaffeinated.

Roasting changes the chemistry, so results from roasted coffee do not automatically apply.

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What the research shows

Several meta-analyses pool small trials. They find small average changes: about 1 to 2.5 kg in weight in favourable analyses (one found no significant weight change), about 3 mmHg in systolic blood pressure, and about 2 mg/dL in fasting glucose. Reviewers describe the trials as few, short and often at high risk of bias.

A 2024 network meta-analysis found drinking green coffee did not reduce weight.

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The retracted trial and the FTC action

A 2012 trial in 16 overweight adults reported large weight loss. It was retracted in 2014. The US FTC settled with the company that sold the extract in 2014, saying the study was so flawed no reliable conclusions could be drawn, and the company agreed to pay $3.5 million. The numbers from that trial are not used on this page.

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Who paid for the research

Reviewers of the blood pressure trials said they were funded by makers of chlorogenic acid. The FTC said the company behind the extract paid for the retracted trial. Funding for the other trials was not given in the abstracts read.

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At a glance

Traditional uses history, not proof

No traditional medicinal use of the unroasted seed was found in the sources read
Sold in modern times as a weight-loss supplement
Sold for blood pressure and blood sugar support

Studied for research

Body weight and BMI, low (small average drops of about 1 to 2.5 kg in favourable analyses, not significant in one)
Blood pressure, low (about 3 mmHg systolic and 2 mmHg diastolic in a 2024 pooled analysis)
Fasting blood sugar and insulin, very low (about 2 mg/dL drop)
Cholesterol and CRP, very low (tiny changes)
Green coffee as a drink for weight, no benefit found in a network meta-analysis

Main compounds

Chlorogenic acid (CID 1794427), the main studied compound
Caffeine (CID 2519), present unless the product is decaffeinated
Caffeic acid, quinic acid, trigonelline

Common forms

Capsule or powder extract (tested in trials, some decaffeinated)
Brewed green coffee drink (tested in tea and coffee drink analysis)
Blends with other ingredients (fat burners; effect cannot be separated)

Research links: US FTC: Green coffee bean manufacturer settles charges · Retraction notice for the 2012 trial (PubMed) · Blood pressure meta-analysis 2024 (PubMed) · EFSA: Caffeine · Research Library · Genes & Biomarkers Library

The plant and its history

Accepted scientific name: Coffea arabica L. and Coffea canephora Pierre ex A.Froehner (the unroasted seeds)
Naming authority: GBIF returned both names as accepted, exact matches.
Common names: green coffee; green coffee bean extract; unroasted coffee; GCE; robusta (C. canephora)
Botanical family: Rubiaceae (the coffee and madder family)
Classification: Gentianales > Rubiaceae > Coffea > Coffea arabica; Coffea canephora
Native range: Not verified from a source.
Habitat: Not verified.
What the plant looks like: Roots: Not described.; Stems: Not described.; Leaves: Not described.; Flowers: Not described.; Fruit: The seed (green bean) is what is used; fruit details not described in sources read.
Cultivation: Not verified.
Harvest and processing: Green coffee is the unroasted seed. A 2022 study measured caffeine in green and roasted C. arabica and found roasting did not change it much.
Look-alikes and adulterants: Roasted coffee: same plant, but roasting changes the chemistry. Chlorogenic acid is the compound most studied in the green bean; roasted-coffee studies in this profile are noted where used.; Green tea: a different plant (Camellia sinensis) also sold for weight loss, with a different liver safety record.
Sustainability and conservation: Not verified.

Traditional use and history history, not clinical proof

Tradition or era	Documented use	Source
Modern supplement	Green coffee extract is sold as a weight-loss and blood-pressure supplement. Public interest rose after a 2012 trial was promoted on television; the FTC later said the study was seriously flawed. The paper was retracted in 2014.	p25340633
Traditional use	No traditional medicinal use of the unroasted seed was found in the sources read.	s-rxlist-green-coffee

Traditional use shows how a plant was used. It does not show that a supplement works or is safe today.

What is inside, and how it may work

What the plant contains and how those compounds act in cells and animals. Laboratory and animal mechanisms are not proven effects in people.

Main compounds

Compound	Family	Where it is concentrated	Activity studied	Level of evidence
Chlorogenic acid (5-caffeoylquinic acid and related isomers) PubChem 1794427	phenolic acids	Seed	Main studied compound. Appears in blood after a dose of green coffee extract (3-, 4- and 5-caffeoylquinic acids, peak about 1 to 1.5 hours). ^{18 17}	Human data
Caffeine PubChem 2519	purine alkaloid	Seed	Stimulant. Caffeine from green coffee extract matched synthetic caffeine in blood levels in a 16-man crossover study. ^{18 17 2}	Human data
Caffeic acid PubChem 689043	phenolic acid	Seed	Breakdown product of chlorogenic acid. Absorption not reviewed here. ¹⁸	Not stated
Quinic acid (quinate) PubChem 6508	cyclitol acid	Seed	Part of the chlorogenic acid molecule. No activity data read. ¹⁸	Not stated
Trigonelline PubChem 5570	alkaloid	Seed	Present in coffee; no activity data read for this profile. ¹⁸	Not stated

Mechanisms, receptors and pathways

Target or pathway	Gene or receptor	What was found	Level
Intestinal glucose absorption	Not specified	In 9 volunteers, decaffeinated coffee lowered GIP and raised GLP-1 after a glucose drink, a pattern consistent with delayed glucose absorption; caffeinated coffee raised early glucose and insulin. ¹⁵	Human data
Homocysteine metabolism	Not specified	Chlorogenic acid at 2 g a day raised plasma total homocysteine in healthy adults over 7 days. ¹⁹	Human data
Non-haem iron absorption	Not specified	Coffee polyphenols inhibit iron uptake from meals in a dose-dependent way. ¹²	Human data
Caffeine metabolism	CYP1A2	Caffeine is cleared by CYP1A2; inhibitors raise caffeine levels. ³	Human (review)

Absorption, metabolism and elimination

Absorption: In 16 healthy men, chlorogenic acids from 480 mg of extract appeared in blood with peaks at about 1 to 1.5 hours; 3-caffeoylquinic acid seemed the most absorbed. Caffeine peaked at about 0.75 hours.
Distribution: No data found.
Metabolism: Caffeine is cleared by CYP1A2 (Carrillo and Benitez 2000). Chlorogenic acid metabolism not read here.
Elimination: No data found.
Bioavailability: Caffeine from the extract matched synthetic caffeine (about 98% ratio for Cmax and AUC).

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Isolated compounds versus whole extracts

Trials used extracts standardised for chlorogenic acid, some decaffeinated and some with caffeine; one dose study of pure chlorogenic acid raised homocysteine. Brewed green coffee as a drink did not reduce weight in a network meta-analysis. The effect of the whole bean versus its parts has not been separated.

Nutritional composition

Green coffee extract is not a nutritional source of vitamins or minerals. Coffee polyphenols can reduce iron absorption from a meal.

8benefits and uses looked at

30studies and sources checked

Low certaintybest evidence rating found

12lab markers tracked in trials

3 low certainty4 very low certainty1 not enough evidence

What is Green Coffee Bean Extract good for?

The studied uses and how strong the human evidence is. "Low" and "very low" mean small or weak research. "No benefit" means the best evidence found no weight change. Safety matters here: see the Safety tab.

Body weight and BMILow certaintyPooled trials show small average weight loss, about 1 to 2.5 kg in favourable analyses, and one large pooled analysis found no significant weight change. Reviewers called the trials few, short and often poor quality. The famous 2012 weight-loss trial was retracted in 2014 and the FTC said it was so flawed no reliable conclusions could be drawn. Waist size and body fatVery low certaintyWaist changes are about half a centimetre in pooled data, and one analysis found none. A 2025 network meta-analysis ranked green coffee first for body fat percentage, but its BMI result was not significant and most comparisons were indirect. Green coffee as a drink (weight)Low certaintyA network meta-analysis of 22 trials found coffee, decaffeinated coffee and green coffee drinks did not reduce weight, while green tea gave a small loss. AppetiteNot enough evidenceOne small trial in metabolic syndrome found a lower appetite score on a decaffeinated extract. No other human trial in the sources read tested it. Blood pressureLow certaintyA 2024 pooled analysis of 10 studies found systolic pressure about 3 mmHg lower and diastolic about 2 mmHg lower, with no change in heart rate. Reviewers of an earlier set of trials said they were small, confined to Asian populations and funded by chlorogenic acid makers. Caffeine can raise blood pressure in some people. Fasting blood sugar and insulinVery low certaintyPooled trials show fasting glucose about 2 mg/dL lower, which is tiny, and insulin results disagree between analyses. HbA1c did not change in the pooled data. No trial in people with diagnosed diabetes was found. CholesterolVery low certaintyTotal cholesterol was about 4 to 6 mg/dL lower in pooled data; other blood fats did not change consistently. Inflammation marker (CRP)Very low certaintyA pooled analysis of 5 studies found a very small drop in CRP, a lab marker, mostly in people who were not healthy.

Benefits, one by one

Each card is a research question, not a promise. Tap a goal to filter. Open a card to see the studies, doses and limits.

Body weight and BMI (green coffee bean extract)

Low certainty

Pooled results from small trials show a small average weight loss of about 1 to 2.5 kg, but the trials are few, short and often poor quality. One large meta-analysis found no significant weight change. The best-known weight-loss trial was retracted.

8 studiesCapsule or powder extracts standardised to chlorogenic acid, some dec…

Studies, doses and limits

What the trials found

Onakpoya 2011 pooled 3 trials (5 eligible), all at high risk of bias, and found 2.47 kg more loss than placebo; the authors called the trials poor quality. Gorji 2019 pooled 16 trials and found a small BMI drop but no significant change in body weight or waist. Kanchanasurakit 2023 pooled only 3 trials (103 people) and found 1.30 kg more loss. An umbrella review of 5 meta-analyses (2024) found 1.22 kg more loss, but those meta-analyses share the same small trials. The famous 2012 Vinson weight-loss trial was retracted in 2014 and the FTC said the study was so flawed that no reliable conclusions could be drawn; its results are not used here.

Results

Small average differences, about 1 to 2.5 kg in the favourable analyses and not significant in one. Not shown to last. Not a replacement for medical weight care.

Effect sizes as reported

Onakpoya 2011: MD -2.47 kg (95% CI -4.23 to -0.72). Gorji 2019: weight WMD -0.585 kg (95% CI -1.498 to 0.329); BMI WMD -0.403 kg/m2 (95% CI -0.800 to -0.005). Kanchanasurakit 2023: WMD -1.30 kg (95% CI -2.07 to -0.52). Umbrella 2024: WMD -1.22 kg (95% CI -1.53 to -0.92).

Why this rating

Few small, short trials, high risk of bias in the oldest reviews, results differ between meta-analyses, and the best-known trial was retracted. The sources we read do not give GRADE for the extract itself.

Form and dose studied

Capsule or powder extracts standardised to chlorogenic acid, some decaffeinated. Product amounts are not given here; ask a doctor or pharmacist.

Who was studied

Adults, mostly overweight or with metabolic problems.

Limits

Abstract-level reading only. Meta-analyses overlap. Funding of the weight trials was not checked; the FTC says the company behind the Vinson trial paid for it, and reviewers of the blood pressure trials say those were funded by chlorogenic acid manufacturers. Trials are short, so long-term effect and safety are unknown.

Why researchers looked

Chlorogenic acids in the unroasted bean are thought to slow sugar absorption and affect fat handling. Caffeine in the bean may also play a part.

Traditional use

Not documented in the sources read. Green (unroasted) coffee extract is a modern supplement.

Proposed mechanism Preliminary mechanism

Lab and animal work suggests chlorogenic acids may slow glucose uptake in the gut; in people a 9-person study found a gut-hormone pattern consistent with slower glucose absorption. This does not show weight loss.

A proposed mechanism does not show that the effect happens in people.

Green coffee products contain caffeine unless decaffeinated; see the safety section. Fat-burner supplements have been linked to liver injury in a case series.

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Waist size and body fat

Very low certainty

A few analyses show tiny waist reductions (about 0.5 cm). A 2025 network meta-analysis ranked green coffee first for body fat percentage, but it rests on few trials with mostly indirect comparisons.

4 studiesCapsule extracts, some decaffeinated. Amounts not listed here.

Studies, doses and limits

What the trials found

Gorji 2019 found no significant waist change (WMD -0.847 cm, CI -1.764 to 0.071). The umbrella review found -0.55 cm (CI -0.80 to -0.31). The 2025 network meta-analysis (39 trials of many plant products) found body fat percentage fell by 2.90 points with green coffee (CI -4.88 to -0.92) while its BMI result was not significant (CI -6.35 to 0.19). In metabolic syndrome patients on a diet, a decaffeinated extract reduced waist by 2.40 cm versus 0.66 cm for placebo (P=0.009).

Results

Small and inconsistent changes; the waist differences are about half a centimetre in pooled data.

Effect sizes as reported

Umbrella 2024: waist WMD -0.55 cm (95% CI -0.80 to -0.31). Network 2025: body fat MD -2.90% (95% CI -4.88 to -0.92). Roshan 2018: waist -2.40 vs -0.66 cm (P=0.009).

Why this rating

Overlapping meta-analyses, indirect comparisons, one small single-country trial, and a non-significant BMI result in the same network analysis.

Form and dose studied

Capsule extracts, some decaffeinated. Amounts not listed here.

Who was studied

Adults with overweight, obesity or metabolic syndrome.

Limits

Abstract-level reading only. Network meta-analysis compared many products indirectly.

Why researchers looked

Fat around the waist is linked to heart and blood sugar problems.

Traditional use

Not documented in the sources read.

Proposed mechanism Preliminary mechanism

Not established. Proposed effects on gut sugar uptake and liver glucose handling come from lab and small human studies.

A proposed mechanism does not show that the effect happens in people.

See safety section for caffeine and liver reports.

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Green coffee as a drink (weight)

Low certainty

A 2024 network meta-analysis of tea and coffee drinks found that coffee, decaffeinated coffee and green coffee drinks did not reduce weight, while green tea gave a small loss.

1 studiesDrinks, not capsules.

Studies, doses and limits

What the trials found

Jayedi 2024 pooled 22 RCTs (1,710 adults, average 10 weeks) of tea and coffee drinks. Green tea beat placebo (MD -1.23 kg; low-certainty evidence). Coffee, decaffeinated coffee, green coffee, black tea and sour tea did not significantly reduce weight. Most trials had a high risk of bias.

Results

No weight benefit found for the green coffee drink.

Effect sizes as reported

Green coffee: not significant; numbers not shown in the abstract.

Why this rating

The reviewers rate green tea evidence low to very low certainty; most trials had high bias risk.

Form and dose studied

Drinks, not capsules.

Who was studied

Adults.

Limits

Drinks only. The green coffee number is not in the abstract.

Why researchers looked

People ask whether the drink gives the same result as the capsule.

Traditional use

Not documented in the sources read.

Proposed mechanism Pharmacological theory

Not applicable; this is a clinical comparison.

A proposed mechanism does not show that the effect happens in people.

Drinks contain caffeine.

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Appetite

Not enough evidence

One small trial in people with metabolic syndrome found a lower appetite score on a decaffeinated extract. No other human trial in the sources read tested appetite.

1 studiesDecaffeinated extract capsules.

Studies, doses and limits

What the trials found

Roshan 2018: appetite score -1.44 (SD 1.72) versus -0.20 (SD 1.32) with placebo (P=0.01) after 8 weeks of a decaffeinated extract.

Results

Lower appetite score in one trial.

Effect sizes as reported

Roshan 2018: -1.44 vs -0.2 points (P=0.01).

Why this rating

A single small trial with a self-rated score.

Form and dose studied

Decaffeinated extract capsules.

Who was studied

Adults with metabolic syndrome.

Limits

One trial; abstract-level reading; sample size not in the abstract.

Why researchers looked

A lower appetite is one proposed route to weight loss.

Traditional use

Not documented in the sources read.

Proposed mechanism Preliminary mechanism

Not established.

A proposed mechanism does not show that the effect happens in people.

None specific.

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Blood pressure

Low certainty

Meta-analyses of small trials find blood pressure falls by roughly 3 mmHg (top number) and 2 mmHg (bottom number), more in people who start with high pressure. The trials are few and several were funded by makers of chlorogenic acid. The caffeine in many products may raise blood pressure in some people.

6 studiesExtracts standardised to chlorogenic acid; some decaffeinated. Amount…

Studies, doses and limits

What the trials found

Samavat 2024 pooled 10 studies (563 adults): systolic -2.95 mmHg and diastolic -2.15 mmHg, no change in heart rate, no effect in females, and no link to dose or duration. Pourmasoumi 2021 (15 studies) found systolic -3.08 mmHg. Onakpoya 2015 pooled 5 trials (364 adults) of chlorogenic acids: systolic -4.31 and diastolic -3.68 mmHg, with high heterogeneity, no adverse events reported, trials confined to Asian populations and funded by CGA manufacturers. Watanabe 2006 (28 adults with mild hypertension) found a drop in the extract group but not placebo. Roshan 2018 (metabolic syndrome, decaffeinated extract, 8 weeks) found systolic pressure fell 13.76 vs 6.56 mmHg (P=0.01).

Results

Small average reductions, bigger in people who already had high blood pressure.

Effect sizes as reported

Samavat 2024: SBP WMD -2.95 mmHg (95% CI -4.27 to -1.62); DBP WMD -2.15 mmHg (95% CI -2.59 to -1.72); HR -1.20 bpm (95% CI -2.93 to 0.51). Onakpoya 2015: SBP MD -4.31 mmHg (95% CI -5.60 to -3.01), DBP MD -3.68 mmHg (95% CI -3.91 to -3.45).

Why this rating

Few small trials, high heterogeneity, manufacturer funding noted by reviewers, narrow populations, and no dose-response pattern. The sources do not give GRADE for the extract.

Form and dose studied

Extracts standardised to chlorogenic acid; some decaffeinated. Amounts not listed here.

Who was studied

Mostly adults in Asia and Iran; stronger in those with high pressure.

Limits

Abstract-level reading only. The effect is small and not a substitute for blood pressure medicine.

Why researchers looked

Chlorogenic acids showed blood pressure lowering in rats, and Japanese researchers tested the bean extract in people with mild high blood pressure.

Traditional use

Not documented in the sources read.

Proposed mechanism Preliminary mechanism

Proposed: chlorogenic acids may improve blood vessel function. In this evidence this is a suggestion, not proven in the trials read.

A proposed mechanism does not show that the effect happens in people.

Caffeine can raise blood pressure in some people. Extracts may add to the effect of blood pressure drugs in theory.

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Fasting blood sugar and insulin

Very low certainty

Pooled results show very small drops in fasting glucose (about 2 mg/dL) and a possible small drop in insulin. These are tiny changes in mostly non-diabetic people. Caffeine itself can push glucose up for a short time.

6 studiesCapsule extracts; the drink study used brewed coffee.

Studies, doses and limits

What the trials found

Chen 2020 (10 trials): fasting glucose -1.791 mg/dL (CI -3.404 to -0.177), insulin not significant. Asbaghi 2020 (14 trials, 766 people): insulin -0.63 microU/L (CI -1.11 to -0.15). Pourmasoumi 2021: fasting glucose -2.21 mg/dL, no effect on HbA1c or HOMA-IR. Roshan 2018: fasting glucose -5.15 vs +29.42 mg/dL and HOMA-IR -1.41 vs +1.23 (P=0.02) in metabolic syndrome. The 2025 network meta-analysis listed African mango and ephedra, not green coffee, as strongest for glucose outcomes.

Results

Tiny changes in fasting glucose; no change in HbA1c in the pooled data. No trial in people with diabetes was identified in the abstracts read.

Effect sizes as reported

Chen 2020: FBS WMD -1.791 mg/dL; insulin WMD -0.925 microU/mL (95% CI -1.915 to 0.064). Pourmasoumi 2021: FPG -2.21 mg/dL (95% CI -3.94 to -0.48).

Why this rating

Changes are about 2 mg/dL, borderline significant, with high heterogeneity for insulin and one trial with extremely wide spread.

Form and dose studied

Capsule extracts; the drink study used brewed coffee.

Who was studied

Mostly adults without diabetes.

Limits

Abstract-level reading. HbA1c did not change. The glucose numbers are not clinically meaningful on their own.

Why researchers looked

Chlorogenic acids may slow sugar absorption from the gut.

Traditional use

Not documented in the sources read.

Proposed mechanism Preliminary mechanism

A 9-person crossover study found that decaffeinated coffee changed gut hormones in a way consistent with slower glucose absorption, while caffeinated coffee raised early glucose and insulin.

A proposed mechanism does not show that the effect happens in people.

If you take diabetes medicine, ask your doctor or pharmacist first; caffeine can affect blood sugar.

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Cholesterol

Very low certainty

Pooled data show total cholesterol about 4 to 6 mg/dL lower. Other fats mostly did not change or depended on single studies.

4 studiesCapsule extracts.

Studies, doses and limits

What the trials found

Asbaghi 2020: total cholesterol WMD -4.51 mg/dL (CI -8.39 to -0.64). Pourmasoumi 2021: total cholesterol -5.93 mg/dL (CI -9.21 to -2.65); no effect on HDL, HbA1c; triglyceride and LDL results depended on individual studies. Roshan 2018 found no lipid change.

Results

Small drop in total cholesterol; not consistent for LDL, HDL or triglycerides.

Effect sizes as reported

See above.

Why this rating

Tiny changes, fragile results, no clinical outcome data.

Form and dose studied

Capsule extracts.

Who was studied

Adults.

Limits

Abstract-level reading. Effects on heart attacks or strokes are unknown.

Why researchers looked

Part of the metabolic picture alongside weight and blood sugar.

Traditional use

Not documented in the sources read.

Proposed mechanism Preliminary mechanism

Not established.

A proposed mechanism does not show that the effect happens in people.

Chlorogenic acid at high amounts raised homocysteine in a short trial; see safety.

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Inflammation marker (CRP)

Very low certainty

A meta-analysis of 5 studies found a very small drop in C-reactive protein, mainly in people who were not healthy.

1 studiesCapsule extracts.

Studies, doses and limits

What the trials found

Chen 2020 (5 studies, 6 arms): CRP WMD -0.017 mg/dL (CI -0.032 to -0.003); larger in non-healthy subjects. The reviewers call for more trials.

Results

A lab-marker change of 0.017 mg/dL, too small to say anything about how people feel.

Effect sizes as reported

WMD -0.017 mg/dL (95% CI -0.032 to -0.003).

Why this rating

Five small studies, tiny change, a biomarker only.

Form and dose studied

Capsule extracts.

Who was studied

Adults including those with high blood pressure, high cholesterol or fatty liver.

Limits

Abstract-level reading only.

Why researchers looked

CRP is a blood marker of inflammation.

Traditional use

Not documented in the sources read.

Proposed mechanism Preliminary mechanism

Not established.

A proposed mechanism does not show that the effect happens in people.

None specific.

⁵

Connections to the rest of health

How Green Coffee Bean Extract connects to the rest of our health knowledge graph. Every link says what kind of connection it is. A safety link (for example to the liver) is a warning, not a benefit. A study that merely mentions a topic never creates a benefit link.

Explore every connection: goals, body systems, organs, symptoms, genes

Kind of connection Connected to Search

A. Wellness goals

Connected to	Kind of connection	Evidence status	Context	Studies
Weight Management	Potential benefit	Low certainty	Body weight and BMI (green coffee bean extract): Pooled results from small trials show a small average weight loss of about 1 to 2.5 kg, but the trials are few, short and often poor quality. One large meta-analysis found no significant weight change. The best-known weight-loss trial was retracted. Waist size and body fat: A few analyses show tiny waist reductions (about 0.5 cm). A 2025 network meta-analysis ranked green coffee first for body fat percentage, but it rests on few trials with mostly indirect comparisons.	^{20 11 16 30 27 6 26 15 29 23 14}
Metabolic Health	Potential benefit	Low certainty	Body weight and BMI (green coffee bean extract): Pooled results from small trials show a small average weight loss of about 1 to 2.5 kg, but the trials are few, short and often poor quality. One large meta-analysis found no significant weight change. The best-known weight-loss trial was retracted. Waist size and body fat: A few analyses show tiny waist reductions (about 0.5 cm). A 2025 network meta-analysis ranked green coffee first for body fat percentage, but it rests on few trials with mostly indirect comparisons.	^{20 11 16 30 27 6 26 15 29 23 4 1 22}
Blood Pressure Support	Potential benefit	Low certainty	Blood pressure: Meta-analyses of small trials find blood pressure falls by roughly 3 mmHg (top number) and 2 mmHg (bottom number), more in people who start with high pressure. The trials are few and several were funded by makers of chlorogenic acid. The caffeine in many products may raise blood pressure in some people.	^{25 22 21 28 23 24}
Heart Health	Potential benefit	Low certainty	Blood pressure: Meta-analyses of small trials find blood pressure falls by roughly 3 mmHg (top number) and 2 mmHg (bottom number), more in people who start with high pressure. The trials are few and several were funded by makers of chlorogenic acid. The caffeine in many products may raise blood pressure in some people. Cholesterol: Pooled data show total cholesterol about 4 to 6 mg/dL lower. Other fats mostly did not change or depended on single studies.	^{25 22 21 28 23 24 1 19}
Blood Sugar Balance	Potential benefit	Very low certainty	Fasting blood sugar and insulin: Pooled results show very small drops in fasting glucose (about 2 mg/dL) and a possible small drop in insulin. These are tiny changes in mostly non-diabetic people. Caffeine itself can push glucose up for a short time.	^{4 1 22 23 15 29}
Cholesterol Balance	Potential benefit	Very low certainty	Cholesterol: Pooled data show total cholesterol about 4 to 6 mg/dL lower. Other fats mostly did not change or depended on single studies.	^{1 22 23 19}
Inflammation Balance	Potential benefit	Very low certainty	Inflammation marker (CRP): A meta-analysis of 5 studies found a very small drop in C-reactive protein, mainly in people who were not healthy.	⁵

B. Body systems

Connected to	Kind of connection	Evidence status	Context	Studies
Metabolism Weight	Biological association	Low certainty	Studied for: Body weight and BMI (green coffee bean extract) Studied for: Waist size and body fat	^{20 11 16 30 27 6 26 15 29 23 14 4 1 22}
Cardiovascular System	Biological association	Low certainty	Studied for: Blood pressure Studied for: Cholesterol	^{25 22 21 28 23 24 1 19}
Endocrine System	Biological association	Very low certainty	Studied for: Fasting blood sugar and insulin	^{4 1 22 23 15 29}
Immune System	Biological association	Very low certainty	Studied for: Inflammation marker (CRP)	⁵

E. Health conditions

Connected to	Kind of connection	Evidence status	Context	Studies
Obesity	Potential benefit	Low certainty	Small average weight changes in pooled small trials. Preparation or compound: Green coffee bean extract	^{20 11 30}
High blood pressure	Potential benefit	Low certainty	About 3/2 mmHg lower in pooled studies. Preparation or compound: Green coffee bean extract	^{25 21}

I. Biomarkers

Connected to	Kind of connection	Evidence status	Context	Studies
Body weight	Biological association	Low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	^{20 11 16 30}
Body mass index (BMI)	Biological association	Low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	^{11 30 29}
Waist circumference	Biological association	Very low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	^{11 30 23}
Body fat percentage	Biological association	Very low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	²⁹
Appetite score	Biological association	Not enough evidence	Measured in trials: lowered. A lab change is not the same as a health benefit.	²³
Systolic blood pressure	Biological association	Low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	^{25 21 23 22}
Diastolic blood pressure	Biological association	Low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	^{25 21}
Heart rate	Biological association	Low certainty	Measured in trials: no-change. A lab change is not the same as a health benefit.	²⁵
Fasting blood glucose	Biological association	Very low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	^{4 22}
Fasting insulin	Biological association	Very low certainty	Measured in trials: mixed. A lab change is not the same as a health benefit.	^{4 1}
Total cholesterol	Biological association	Very low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	^{1 22}
C-reactive protein (CRP)	Biological association	Very low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	⁵

J. Genes, receptors and enzymes

Connected to	Kind of connection	Evidence status	Context	Studies
CYP1A2	Preliminary mechanism	Human (review)	Main enzyme that clears caffeine.	³

L. Active compounds

Connected to	Kind of connection	Evidence status	Context	Studies
Chlorogenic acid (5-caffeoylquinic acid and related isomers)	Biological association	Human	Main studied compound. Appears in blood after a dose of green coffee extract (3-, 4- and 5-caffeoylquinic acids, peak about 1 to 1.5 hours). Preparation or compound: Seed	^{18 17}
Caffeine	Biological association	Human	Stimulant. Caffeine from green coffee extract matched synthetic caffeine in blood levels in a 16-man crossover study. Preparation or compound: Seed	^{18 17 2}
Caffeic acid	Biological association	Not stated	Breakdown product of chlorogenic acid. Absorption not reviewed here. Preparation or compound: Seed	¹⁸
Quinic acid (quinate)	Biological association	Not stated	Part of the chlorogenic acid molecule. No activity data read. Preparation or compound: Seed	¹⁸
Trigonelline	Biological association	Not stated	Present in coffee; no activity data read for this profile. Preparation or compound: Seed	¹⁸

Each connection is stored with the ingredient, the connected record, the kind of connection, the evidence status, the supporting studies, the preparation or compound involved, and a review date (last reviewed October 25, 2026).

Evidence at a glance: what changed in 12 lab markers

Tap a number to show only those markers. Counts are markers, not people.

Metabolic3 Other711

The evidence

The research centre for Green Coffee Bean Extract. Every record here was checked against PubMed or the publisher's page; we never list a study we have not verified.

Evidence by outcome

Body weight and BMI (green coffee bean extract) 8 studies · 25 people in trials Low certainty Waist size and body fat 4 studies Very low certainty Green coffee as a drink (weight) 1 studies Low certainty Appetite 1 studies Not enough evidence Blood pressure 6 studies · 28 people in trials Low certainty Fasting blood sugar and insulin 6 studies · 9 people in trials Very low certainty Cholesterol 4 studies · 20 people in trials Very low certainty Inflammation marker (CRP) 1 studies Very low certainty

Bars show how many studies we found for each outcome, not how well it works. People are added up across trials only (reviews are not added, to avoid double counting).

How we rate evidence

High certainty

Several well-run trials or reviews agree; further research is unlikely to change the picture much.

Moderate certainty

Good trials point the same way, but some doubt remains.

Low certainty

Small, short or inconsistent trials. The finding could change with better research.

Very low certainty

Very little or very weak human data. Treat as a possibility only.

Mixed findings

Trials or reviews disagree with each other.

Not enough evidence

Not enough human research to say either way.

Evidence against

Good research found no benefit, or found harm.

We take the reviewers' own risk-of-bias and GRADE statements where they exist, and otherwise judge from study size, design, consistency, directness and whether a product matches what is sold. Many publications do not make evidence high. Method note: We searched PubMed, read the US FTC release, the RxList green coffee page and the EFSA caffeine page, and recorded each study design and limits. Pages that could not be opened are marked not read.

Study library: every study we checked 30

Design Research type Plant part Year from Search

Study	Design	People	Product, dose, length	Result
Asbaghi 2020 The effects of green coffee extract supplementation on glycemic indices and lipid profile in adults: a systematic review and dose-response meta-analysis of clinical trials. Nutr J · PMID 32665012 · DOI	Meta-analysis	766 14 clinical trials	Green coffee extract (GCE) unspecified varied varied · vs control	Fasting glucose and insulin fell and total cholesterol fell slightly; other lipid changes only in some subgroups. Insulin WMD -0.63 microU/L; total cholesterol WMD -4.51 mg/dL (Insulin 95% CI -1.11 to -0.15; TC CI -8.39 to -0.64) Methods, limits and funding Outcomes: Fasting glucose, insulin, lipids Limitations: Fasting glucose number not shown in the abstract text read; subgroup findings are exploratory. Funding and conflicts: Authors declare no competing interests. Read: abstract
Bobková 2022 Variability of caffeine content in green and roasted Coffea arabica regarding the origin, post-harvest processing, and altitude, and overview of recommended daily allowance. J Environ Sci Health B · PMID 36573489 · DOI	Other in-vitro	Green and roasted Coffea arabica samples from Africa, Asia, Central and South America	Green and roasted C. arabica beans (lab analysis) seed not applicable not applicable · vs not applicable	Green-bean caffeine varied by origin (Central America highest, Africa lowest) and roasting did not change it much. The authors cite 400 mg a day as the EFSA level for non-pregnant adults. Pattern: Central America > South America > Asia > Africa Methods, limits and funding Outcomes: Caffeine content by origin, processing and altitude Limitations: Beans, not capsules or extracts; the abstract gives no mg figures; C. arabica only, so it says nothing about C. canephora. Read: abstract
Carrillo 2000 Clinically significant pharmacokinetic interactions between dietary caffeine and medications. Clin Pharmacokinet · PMID 10976659 · DOI	Systematic review	Review of caffeine and drug interactions	Dietary caffeine not applicable not applicable not applicable · vs not applicable	Caffeine is broken down by the liver enzyme CYP1A2. Drugs that block this enzyme (fluvoxamine, mexiletine, clozapine, theophylline, quinolones such as enoxacin) can raise caffeine levels and cause caffeine toxicity. Toxic effects include seizures, delirium and arrhythmia. narrative review Methods, limits and funding Outcomes: Pharmacokinetic interactions Limitations: A 2000 narrative review of caffeine in general, not of green coffee. Read: abstract
Chen 2020 The influence of green coffee bean extract supplementation on blood glucose levels: A systematic review and dose-response meta-analysis of randomized controlled trials. Phytother Res · PMID 32159261 · DOI	Meta-analysis	10 trials reporting fasting glucose and insulin	Green coffee extract or CGA unspecified insulin result stronger at 400 mg/day or more (reviewers) varied · vs placebo/control	Fasting glucose fell by a very small amount; insulin overall did not change significantly. FBS WMD -1.791 mg/dL; insulin WMD -0.925 microU/mL (not significant) (FBS 95% CI -3.404 to -0.177; insulin CI -1.915 to 0.064 (I2=87.9%)) Methods, limits and funding Outcomes: Fasting glucose and insulin Limitations: A drop of under 2 mg/dL is tiny; barely significant; high heterogeneity for insulin. Read: abstract
Chen 2020 Effects of green coffee bean extract on C-reactive protein levels: A systematic review and meta-analysis of randomized controlled trials. Complement Ther Med · PMID 32951749 · DOI	Meta-analysis	5 studies (6 arms) reporting CRP	Green coffee bean extract (GCBE) seed larger drop at 1000 mg/day or more (reviewers) varied · vs placebo/control	A very small drop in CRP, mostly in people who were not healthy. CRP WMD -0.017 mg/dL (95% CI -0.032 to -0.003) Methods, limits and funding Outcomes: C-reactive protein (CRP) Limitations: Only 5 studies; the effect is tiny; reviewers say more trials are needed. Read: abstract
Diabetes Metab Syndr Obes 2014 Randomized, double-blind, placebo-controlled, linear dose, crossover study to evaluate the efficacy and safety of a green coffee bean extract in overweight subjects [Retraction]. Diabetes Metab Syndr Obes · PMID 25340633 · DOI	Other	Not applicable	Retraction notice unspecified not applicable not applicable · vs not applicable	Notice that retracts the 2012 green coffee weight-loss trial (PMID 22291473). Retraction Methods, limits and funding Outcomes: Retraction of the 2012 Vinson study Limitations: The notice record in PubMed has no abstract text; the reason is given in the FTC release and press coverage, not in the PubMed record. Read: summary-only
European Food Safety Authority 2015 Scientific Opinion on the safety of caffeine (EFSA topic page) EFSA · Source	Authoritative guidance	not applicable	unspecified not applicable not applicable · vs not applicable	EFSA (27 May 2015): single doses of caffeine up to 200 mg and habitual intake up to 400 mg a day from all sources do not raise safety concerns for healthy adults; up to 200 mg a day does not raise concerns for the foetus in pregnant women. Methods, limits and funding Limitations: About caffeine from all sources, not green coffee extract specifically. The topic page was read, not the full opinion. Read: summary-only
GBIF 2026 GBIF Backbone: Coffea arabica L. GBIF species API · Source	Database record not applicable	not applicable	unspecified not applicable not applicable · vs not applicable	Accepted name Coffea arabica L., family Rubiaceae, order Gentianales (GBIF key 2895345). Methods, limits and funding Limitations: Database record only. Read: full-text
GBIF 2026 GBIF Backbone: Coffea canephora Pierre ex A.Froehner GBIF species API · Source	Database record not applicable	not applicable	unspecified not applicable not applicable · vs not applicable	Accepted name Coffea canephora Pierre ex A.Froehner, family Rubiaceae (GBIF key 2895528). Methods, limits and funding Limitations: Database record only. Read: full-text
Gavrić 2018 Fat burner-induced acute liver injury: Case series of four patients. Nutrition · PMID 29310849 · DOI	Case series	4 4 patients in Slovenia (5 liver injury episodes) who had taken fat-burner supplements	Different commercial fat burners: green tea extract, Garcinia gummi-gutta, green coffee beans and spirulina unspecified not stated not stated · vs none	One patient had acute liver failure needing a liver transplant; one had hepatitis that resolved; one had severe bleeding after liver biopsy; one had two separate episodes. The authors say unsupervised use of fat burners was the most likely cause after other causes were excluded. 4 patients (not applicable) Methods, limits and funding Outcomes: Liver injury Limitations: The abstract does not say which patient took which product, so green coffee cannot be singled out; products were multi-ingredient. Read: abstract
Gorji 2019 The effect of green-coffee extract supplementation on obesity: A systematic review and dose-response meta-analysis of randomized controlled trials. Phytomedicine · PMID 31398662 · DOI	Meta-analysis	Adults, 13 articles with 16 RCTs	Green coffee extract or chlorogenic acid unspecified varied varied; under 4 weeks had no effect · vs placebo/control	BMI fell slightly; body weight and waist did not change significantly overall. Larger gains in people with BMI of 25 or more. BMI WMD -0.403 kg/m2; weight WMD -0.585 kg; waist WMD -0.847 cm (BMI 95% CI -0.800 to -0.005 (P=0.047); weight CI -1.498 to 0.329; waist CI -1.764 to 0.071) Methods, limits and funding Outcomes: Body weight, BMI, waist circumference Limitations: Abstract-level read; the BMI result only just reached significance; trial quality not summarised in abstract; an erratum exists. Read: abstract
Hurrell 1999 Inhibition of non-haem iron absorption in man by polyphenolic-containing beverages. Br J Nutr · PMID 10999016	Controlled trial	Adult volunteers	Polyphenol drinks including coffee (chlorogenic acid) with a bread meal not applicable not stated in abstract single meals · vs water	All polyphenol drinks tested cut iron absorption from the meal, dose-dependently; coffee, tea, cocoa and herb teas were all inhibitors. Beverages with 20-50 mg polyphenols cut absorption 50-70%; 100-400 mg cut it 60-90% (versus water) (not in abstract) Methods, limits and funding Outcomes: Non-haem iron absorption (radio-iron) Limitations: Brewed drinks with a bread meal, not green coffee capsules; the abstract does not give the coffee-only percentage. Read: abstract
Jahanfar 2015 Effects of restricted caffeine intake by mother on fetal, neonatal and pregnancy outcomes. Cochrane Database Syst Rev · PMID 26058966 · DOI	Systematic review	1197 Pregnant regular coffee drinkers (3 or more cups a day), one trial with data	Caffeinated vs decaffeinated instant coffee not applicable average 182 mg/day less caffeine second and third trimester · vs decaffeinated coffee	Cutting about 182 mg a day of caffeine did not change birthweight, preterm birth or small size for age. Cochrane says the evidence is insufficient either way. Birthweight MD 20.00 g (95% CI -48.68 to 88.68) Methods, limits and funding Outcomes: Birthweight, preterm birth, small-for-gestational-age Limitations: Only one trial contributed data; low-quality evidence; this is about restricting caffeine, not a test of green coffee. Funding and conflicts: Cochrane: none known. Read: abstract
Jayedi 2024 Comparative effects of tea and coffee drinking on body weight in adults: a systematic review and network meta-analysis of randomised trials. Br J Nutr · PMID 39497467 · DOI	Meta-analysis	1710 Adults in 22 RCTs of tea and coffee drinks (average 10 weeks)	Green tea, coffee, decaffeinated coffee, green coffee, black tea, sour tea as drinks unspecified not extracted average 10 weeks · vs placebo or water	Green tea gave a small weight loss (low to very low certainty). Coffee, decaffeinated coffee and green coffee drinks did not reduce weight. Green tea vs placebo MD -1.23 kg; green coffee: no significant effect (Green tea 95% CrI -2.45 to -0.02) Methods, limits and funding Outcomes: Body weight Limitations: Drinks, not capsule extracts. Most trials high risk of bias; only 5 longer trials. Green coffee numbers not given in the abstract. Read: abstract
Johnston 2003 Coffee acutely modifies gastrointestinal hormone secretion and glucose tolerance in humans: glycemic effects of chlorogenic acid and caffeine. Am J Clin Nutr · PMID 14522730 · DOI	Controlled trial	9 9 healthy fasted adults	Caffeinated and decaffeinated brewed coffee (about 2.5 mmol CGA per litre) seed 400 mL coffee with 25 g glucose single sitting, crossover · vs water	Caffeinated coffee raised early glucose and insulin; decaffeinated coffee changed gut hormones in a way that fits slower glucose absorption. Glucose and insulin tended to be higher in the first 30 min after caffeinated coffee (P<0.05) (not in abstract) Methods, limits and funding Outcomes: Glucose, insulin and gut hormones for 3 hours Limitations: Nine people, one sitting, brewed coffee (probably roasted, not a green extract), so it shows caffeine versus chlorogenic acid effects only in principle. Read: abstract
Kanchanasurakit 2023 Chlorogenic acid in green bean coffee on body weight: a systematic review and meta-analysis of randomized controlled trials. Syst Rev · PMID 37710316 · DOI	Meta-analysis	103 Adults in 3 RCTs	Green bean coffee extract (GBCE) with chlorogenic acid unspecified at least 500 mg CGA/day (as stated by reviewers) short-term · vs placebo	Pooled body weight fell with GBCE; no heterogeneity; reviewers say sample size is small and trials are short. WMD -1.30 kg (95% CI -2.07 to -0.52) Methods, limits and funding Outcomes: Body weight Limitations: Only 3 trials, 103 people, short. Registered PROSPERO CRD42021254916. Funding and conflicts: Authors declare no competing interests. Registration: PROSPERO CRD42021254916 Read: abstract
Morton 2018 A Prospective Randomized, Double-Blind, Two-Period Crossover Pharmacokinetic Trial Comparing Green Coffee Bean Extract-A Botanically Sourced Caffeine-With a Synthetic USP Control. Clin Pharmacol Drug Dev · PMID 29659178 · DOI	Controlled trial	16 16 healthy men	Green coffee bean extract (480 mg extract supplying 60 mg caffeine) vs 60 mg synthetic caffeine seed 480 mg extract / 60 mg caffeine, single dose single dose, 5-day gap, crossover · vs synthetic USP caffeine	The chlorogenic acids from the extract appeared in blood (peak at about 1 to 1.5 hours); caffeine levels were statistically similar to synthetic caffeine; no adverse events. Caffeine Cmax and AUC ratio about 98% (natural vs synthetic) (not in abstract) Methods, limits and funding Outcomes: Blood levels of three chlorogenic acids and caffeine Limitations: 16 men, one dose; funding not stated in the abstract. Read: abstract
NCBI PubChem 2026 PubChem compound records: chlorogenic acid, caffeine, caffeic acid, quinic acid, trigonelline PubChem · Source	Database record not applicable	not applicable	unspecified not applicable not applicable · vs not applicable	Chlorogenic acid CID 1794427 (C16H18O9); caffeine CID 2519 (C8H10N4O2); caffeic acid CID 689043 (C9H8O4); quinic acid (quinate) CID 6508 (C7H12O6); trigonelline CID 5570 (C7H7NO2). Methods, limits and funding Limitations: Names, formulas and CIDs read from the PubChem API. Read: full-text
Olthof 2001 Consumption of high doses of chlorogenic acid, present in coffee, or of black tea increases plasma total homocysteine concentrations in humans. Am J Clin Nutr · PMID 11237928 · DOI	Controlled trial	20 20 healthy men and women	Pure chlorogenic acid not applicable 2 g per day (as reported) 7 days per treatment, crossover · vs placebo, black tea, quercetin-3-rutinoside	Homocysteine was higher 4-5 hours after chlorogenic acid. The authors say it is not known whether this changes heart disease risk. +12% (1.2 micromol/L) at 4-5 h; +4% (0.4 micromol/L) in fasting blood (4-5 h 95% CI 0.6 to 1.7; fasting 0.0 to 0.8) Methods, limits and funding Outcomes: Plasma total homocysteine Limitations: Pure chlorogenic acid at 2 g a day, a high amount; healthy volunteers; short; clinical meaning unknown. Read: abstract
Onakpoya 2011 The use of green coffee extract as a weight loss supplement: a systematic review and meta-analysis of randomised clinical trials. Gastroenterol Res Pract · PMID 20871849 · DOI	Meta-analysis	Adults in 3 included randomised trials of green coffee extract for weight loss	Green coffee extract (GCE) unspecified not extracted varied by trial · vs placebo	Body weight fell more with GCE than placebo. All studies had a high risk of bias and results differed a lot between trials. Mean difference -2.47 kg (95% CI -4.23 to -0.72) Methods, limits and funding Outcomes: Body weight Limitations: Only 3 trials pooled (5 eligible); all high risk of bias; large heterogeneity; the authors call the trials poor quality. Read: abstract
Onakpoya 2015 The effect of chlorogenic acid on blood pressure: a systematic review and meta-analysis of randomized clinical trials. J Hum Hypertens · PMID 24943289 · DOI	Meta-analysis	364 Adults, 5 RCTs with 364 participants	Chlorogenic acids (CGA), mostly from green coffee unspecified varied varied · vs placebo	Both pressures fell. All studies reported no adverse events. The authors note trials were few, differed in design, were confined to Asian populations and were funded by CGA manufacturers. SBP MD -4.31 mmHg; DBP MD -3.68 mmHg (SBP 95% CI -5.60 to -3.01 (I2=65%); DBP -3.91 to -3.45 (I2=97%)) Methods, limits and funding Outcomes: Systolic and diastolic blood pressure Limitations: Very high heterogeneity for diastolic pressure; small trials; funded by manufacturers per the reviewers. Funding and conflicts: Reviewers state the included trials were funded by CGA manufacturers. Read: abstract
Pourmasoumi 2021 The Effect of Green Coffee Bean Extract on Cardiovascular Risk Factors: A Systematic Review and Meta-analysis. Adv Exp Med Biol · PMID 34981487 · DOI	Meta-analysis	637 15 studies (19 arms)	Green coffee bean extract seed varied varied · vs placebo/control	Small drops in cholesterol, fasting glucose, blood pressure and BMI; several other results depended on single studies; no effect on triglycerides, HDL, HbA1c or HOMA-IR. TC -5.93 mg/dL; FPG -2.21 mg/dL; SBP -3.08 mmHg; BMI -0.55 kg/m2 (TC CI -9.21 to -2.65; FPG CI -3.94 to -0.48; SBP CI -4.41 to -1.75; BMI CI -0.88 to -0.22) Methods, limits and funding Outcomes: Lipids, glucose, blood pressure, BMI Limitations: Several results fragile; no certainty rating in abstract; some numbers cut off in the abstract text read. Read: abstract
Roshan 2018 Effects of green coffee extract supplementation on anthropometric indices, glycaemic control, blood pressure, lipid profile, insulin resistance and appetite in patients with the metabolic syndrome: a randomised clinical trial. Br J Nutr · PMID 29307310 · DOI	Controlled trial	Adults with metabolic syndrome (Iran)	Decaffeinated green coffee bean extract seed 400 mg capsules twice a day (from the abstract) 8 weeks · vs placebo capsules; both groups on an energy-balanced diet	Systolic blood pressure, fasting glucose, HOMA-IR, waist and appetite score improved more than placebo; weight loss only marginal (P=0.05); no change in HbA1c or lipids. SBP -13.76 vs -6.56 mmHg (P=0.01); HOMA-IR -1.41 vs +1.23 (P=0.02); waist -2.40 vs -0.66 cm (P=0.009); weight -2.08 vs -0.92 kg (P=0.05) (not in abstract) Methods, limits and funding Outcomes: Weight, glucose, blood pressure, lipids, insulin resistance, appetite Limitations: Single small trial in one country; sample size not in the abstract; fasting glucose result has very large spread (SD 60 mg/dL); decaffeinated, so not the same as caffeinated products. Read: abstract
RxList 2026 Green Coffee: Health Benefits, Side Effects, Uses, Dose and Precautions RxList (consumer drug reference) · Source	Authoritative guidance	not applicable	unspecified not applicable not applicable · vs not applicable	Rated possibly safe by mouth; caffeine-type side effects listed (insomnia, nervousness, stomach upset, fast heartbeat); advises avoiding in pregnancy and breastfeeding because reliable information is insufficient; lists cautions (anxiety, bleeding disorders, diabetes, glaucoma, high blood pressure, osteoporosis, high homocysteine) and a table of interactions rated moderate or minor. Its text says it does not state the product caffeine content. Methods, limits and funding Limitations: A consumer reference with no date on the page; interaction ratings are mostly theory from caffeine, not green coffee trials; no liver section. Read: full-text
Samavat 2024 The effects of green coffee bean extract on blood pressure and heart rate: A systematic review and dose-response meta-analysis of randomized controlled trials. Diabetes Metab Syndr · PMID 39368321 · DOI	Meta-analysis	563 Adults, 10 studies	Green coffee bean extract (GCBE) unspecified no dose-response link found varied · vs placebo/control	Blood pressure fell a little overall; more in people who started with high blood pressure; no effect in females; heart rate did not change. SBP WMD -2.95 mmHg; DBP -2.15 mmHg; heart rate -1.20 bpm (not significant) (SBP 95% CI -4.27 to -1.62; DBP -2.59 to -1.72; HR -2.93 to 0.51) Methods, limits and funding Outcomes: Systolic and diastolic blood pressure, heart rate Limitations: Only 10 small studies; no certainty rating in the abstract; dose and duration did not predict the effect, which weakens the case for a real dose-driven effect. Funding and conflicts: Authors declare no competing interests. Read: abstract
US Federal Trade Commission 2014 Green coffee bean manufacturer settles FTC charges of pushing its product based on results of a seriously flawed study FTC press release · Source	Authoritative guidance	not applicable	unspecified not applicable not applicable · vs not applicable	FTC says Applied Food Sciences paid researchers in India for a green coffee extract trial, that the lead investigator altered weights and other measures and misstated who got placebo, and that the company then had University of Scranton researchers rewrite it. The company agreed to pay $3.5 million and to hold at least two well-controlled human trials before making future weight-loss claims. Methods, limits and funding Limitations: Press release read in full via fetch; the page text read did not mention the retraction. Proposed order was subject to court approval when announced. Funding and conflicts: Regulator document Read: full-text
Vinson 2012 Randomized, double-blind, placebo-controlled, linear dose, crossover study to evaluate the efficacy and safety of a green coffee bean extract in overweight subjects. Diabetes Metab Syndr Obes · PMID 22291473 · DOI	Controlled trial	16 16 overweight adults	Green coffee extract product (GCA, as named in the paper) unspecified not used here 22-week crossover · vs placebo	This 2012 paper was RETRACTED in 2014. Its findings are not used anywhere on this page. not used (not used) Methods, limits and funding Outcomes: Weight, BMI, body fat Limitations: Retracted: the sponsors could not assure the validity of the data (as stated in coverage of the retraction; see FTC release). Included only to document the retraction. Funding and conflicts: FTC says the company that sold the extract paid for the trial. Read: abstract
Watanabe 2006 The blood pressure-lowering effect and safety of chlorogenic acid from green coffee bean extract in essential hypertension. Clin Exp Hypertens · PMID 16820341 · DOI	Controlled trial	28 Adults with mild essential hypertension (Japan)	Chlorogenic acid from green coffee bean extract seed CGA 140 mg/day (from the abstract) not stated in abstract · vs placebo	Blood pressure fell in the CGA group and not in placebo; no apparent side effects; no change in pulse rate or BMI. Numbers not given in abstract (not in abstract) Methods, limits and funding Outcomes: Blood pressure, pulse, safety measures Limitations: Tiny trial; abstract gives no numbers or duration. Funding and conflicts: Funding not stated in abstract. The 2015 review says trials in this field were funded by CGA manufacturers. Read: abstract
Wiyarta 2025 Plant-Derived Natural Products for Dietary Intervention in Overweight and Obese Individuals: A Systematic Review and Network Meta-Analysis. Phytother Res · PMID 40420357 · DOI	Meta-analysis	2513 Adults with overweight or obesity, 39 RCTs of many plant products	Many plant products (green coffee among them) unspecified varied varied · vs placebo	Green coffee led the ranking for body fat percentage but its BMI result was not significant. Most comparisons were indirect. Body fat % MD -2.90 (green coffee); BMI MD -3.08 kg/m2 (green coffee) (Body fat 95% CI -4.88 to -0.92; BMI CI -6.35 to 0.19 (crosses zero)) Methods, limits and funding Outcomes: 13 metabolic outcomes Limitations: Network meta-analysis of many products with mostly indirect comparisons; the authors say high-quality trials are needed; green coffee numbers rest on few trials. Registration: PROSPERO CRD42024520305 Read: abstract
Yang 2024 The effect of green coffee extract supplementation on obesity indices: critical umbrella review of interventional meta-analyses. Crit Rev Food Sci Nutr · PMID 37341701 · DOI	Meta-analysis	Umbrella review of 5 meta-analyses of green coffee extract trials	Green coffee extract unspecified subgroup: 600 mg/day or less and more than 7 weeks more likely to lower weight (reviewers) varied · vs placebo/control	Pooled across the 5 meta-analyses, small reductions in weight, BMI and waist. Weight WMD -1.22 kg; BMI -0.48 kg/m2; waist -0.55 cm (Weight 95% CI -1.53 to -0.92; BMI -0.67 to -0.29; waist -0.80 to -0.31) Methods, limits and funding Outcomes: Body weight, BMI, waist circumference Limitations: An umbrella review re-uses the same small trials, so the five meta-analyses overlap and the result is not independent confirmation. Abstract does not give certainty ratings. Read: abstract

What we do not know yet

No large, independent, long-term trial for weight.
The retracted 2012 trial removed the best-known positive result.
Caffeine versus chlorogenic acid effects are not separated.
No EMA/HMPC, NCCIH, LiverTox or LactMed entry was found or readable.
No pregnancy or breastfeeding data for the extract.
Interaction ratings come from a consumer reference and caffeine literature, not green coffee trials.

How new research is added

New studies are found by a saved PubMed search and placed in a review queue. A person reads each one before it changes any rating or safety wording.

Lab markers

What changed in blood or saliva tests during trials. A changed number is not the same as feeling or being healthier, and we give no "normal ranges".

Metabolic 3

▼

Body weight

Lowered in trials

Weight on a scale.

Low certainty

Results and what it means

Why it was measured

Main outcome of the weight trials.

Statistical vs. clinical meaning

Results differ between analyses; one is not significant. A kilogram or two is small next to the uncertainty.

Safety implication

None directly.

Study	Result	People	Product
²⁰	MD -2.47 kg (95% CI -4.23 to -0.72); all studies high risk of bias.	Adults in 3 trials	GCE vs placebo
¹¹	WMD -0.585 kg (95% CI -1.498 to 0.329), not significant.	Adults, 16 RCTs	GCE or CGA vs control
¹⁶	WMD -1.30 kg (95% CI -2.07 to -0.52).	103 adults, 3 RCTs	Extract with CGA vs placebo
³⁰	WMD -1.22 kg (95% CI -1.53 to -0.92).	5 meta-analyses pooled	GCE vs control

^{20 11 16 30}

▼

Body mass index (BMI)

Lowered in trials

Weight divided by height squared.

Low certainty

Results and what it means

Why it was measured

A common measure of overweight.

Statistical vs. clinical meaning

Tiny average change; one analysis is just significant and another is not.

Safety implication

None directly.

Study	Result	People	Product
¹¹	WMD -0.403 kg/m2 (95% CI -0.800 to -0.005).	Adults, 16 RCTs	GCE or CGA vs control
³⁰	WMD -0.48 kg/m2 (95% CI -0.67 to -0.29).	5 meta-analyses	GCE vs control
²⁹	MD -3.08 kg/m2 (95% CI -6.35 to 0.19), not significant, in a network meta-analysis.	39 trials of plant products	Green coffee vs placebo

^{11 30 29}

▼

Total cholesterol

Lowered in trials

Cholesterol in blood.

Very low certainty

Results and what it means

Why it was measured

Heart risk marker.

Statistical vs. clinical meaning

A few mg/dL.

Safety implication

None directly.

Study	Result	People	Product
¹	WMD -4.51 mg/dL (95% CI -8.39 to -0.64).	14 trials	GCE vs control
²²	-5.93 mg/dL (95% CI -9.21 to -2.65).	15 studies	GBE vs control

^{1 22}

Other 9

▼

Waist circumference

Lowered in trials

Distance around the waist.

Very low certainty

Results and what it means

Why it was measured

Marks fat around the middle.

Statistical vs. clinical meaning

Half a centimetre is not clinically noticeable.

Safety implication

None directly.

Study	Result	People	Product
¹¹	WMD -0.847 cm (95% CI -1.764 to 0.071), not significant.	Adults, 16 RCTs	GCE or CGA vs control
³⁰	WMD -0.55 cm (95% CI -0.80 to -0.31).	5 meta-analyses	GCE vs control
²³	-2.40 vs -0.66 cm (P=0.009).	Metabolic syndrome, 8 weeks	Decaffeinated GCE vs placebo

^{11 30 23}

▼

Body fat percentage

Lowered in trials

Share of body weight that is fat.

Very low certainty

Results and what it means

Why it was measured

Better than weight alone for fat loss.

Statistical vs. clinical meaning

One indirect network result; few green coffee trials behind it.

Safety implication

None directly.

Study	Result	People	Product
²⁹	MD -2.90 percentage points (95% CI -4.88 to -0.92).	39 trials of plant products (network analysis)	Green coffee vs placebo

²⁹

▼

Appetite score

Lowered in trials

Self-rated hunger.

Not enough evidence

Results and what it means

Why it was measured

Linked to eating less.

Statistical vs. clinical meaning

One small trial.

Safety implication

None directly.

Study	Result	People	Product
²³	-1.44 vs -0.2 points (P=0.01).	Metabolic syndrome, 8 weeks	Decaffeinated GCE vs placebo

²³

▼

Systolic blood pressure

Lowered in trials

The top blood pressure number.

Low certainty

Results and what it means

Why it was measured

A standard heart risk marker.

Statistical vs. clinical meaning

A few mmHg; clinical benefit not shown.

Safety implication

Caffeine can raise pressure.

Study	Result	People	Product
²⁵	WMD -2.95 mmHg (95% CI -4.27 to -1.62).	563 adults, 10 studies	GCBE vs control
²¹	MD -4.31 mmHg (95% CI -5.60 to -3.01).	364 adults, 5 trials	CGA vs placebo
²³	-13.76 vs -6.56 mmHg (P=0.01).	Metabolic syndrome	Decaffeinated GCE 8 weeks

^{25 21 23 22}

▼

Diastolic blood pressure

Lowered in trials

The bottom blood pressure number.

Low certainty

Results and what it means

Why it was measured

A standard heart risk marker.

Statistical vs. clinical meaning

Small change with high heterogeneity.

Safety implication

Same as systolic.

Study	Result	People	Product
²⁵	WMD -2.15 mmHg (95% CI -2.59 to -1.72).	563 adults, 10 studies	GCBE vs control
²¹	MD -3.68 mmHg (95% CI -3.91 to -3.45), I2=97%.	364 adults, 5 trials	CGA vs placebo

^{25 21}

●

Heart rate

No clear change in trials

Beats per minute.

Low certainty

Results and what it means

Why it was measured

Checks for a stimulant effect.

Statistical vs. clinical meaning

No significant change in pooled data.

Safety implication

Reassuring in trials, but caffeine content varied.

Study	Result	People	Product
²⁵	WMD -1.20 bpm (95% CI -2.93 to 0.51), not significant.	563 adults	GCBE vs control

²⁵

▼

Fasting blood glucose

Lowered in trials

Blood sugar after not eating.

Very low certainty

Results and what it means

Why it was measured

Diabetes and prediabetes marker.

Statistical vs. clinical meaning

About 2 mg/dL is below normal day-to-day variation.

Safety implication

May interact with diabetes drugs in theory.

Study	Result	People	Product
⁴	WMD -1.791 mg/dL (95% CI -3.404 to -0.177).	10 trials	GCE vs control
²²	-2.21 mg/dL (95% CI -3.94 to -0.48).	15 studies	GBE vs control

^{4 22}

↕

Fasting insulin

Mixed results in trials

Insulin level after fasting.

Very low certainty

Results and what it means

Why it was measured

Marker of insulin resistance.

Statistical vs. clinical meaning

The two meta-analyses disagree on significance.

Safety implication

None directly.

Study	Result	People	Product
⁴	WMD -0.925 microU/mL (95% CI -1.915 to 0.064), not significant; I2=87.9%.	10 trials	GCE vs control
¹	WMD -0.63 microU/L (95% CI -1.11 to -0.15).	14 trials	GCE vs control

^{4 1}

▼

C-reactive protein (CRP)

Lowered in trials

Blood marker of inflammation.

Very low certainty

Results and what it means

Why it was measured

General inflammation marker.

Statistical vs. clinical meaning

Tiny change.

Safety implication

None directly.

Study	Result	People	Product
⁵	WMD -0.017 mg/dL (95% CI -0.032 to -0.003).	5 studies	GCBE vs control

⁵

Safety

What studies and official sources say about side effects, medicines and who should check first. Each point shows what kind of evidence it comes from.

Main points to know 4

Most products contain caffeine. Unroasted coffee beans contain caffeine, and extracts sold for weight loss often keep it unless labelled decaffeinated. RxList lists caffeine-type effects: insomnia, nervousness, restlessness, upset stomach, nausea, and faster heart and breathing rates, and with large amounts headache, anxiety, ringing in the ears and irregular heartbeat. The sources we read do not give a caffeine amount for green coffee products, so check the label. Authoritative guidance ^{24 2}
Liver injury has been reported with fat-burner products that included green coffee. A Slovenian case series of 4 patients with 5 episodes of liver injury linked it to fat-burner supplements including green tea extract, Garcinia, green coffee beans and spirulina. One patient needed a liver transplant. The abstract does not say which patient took which product, so green coffee cannot be singled out. Case series ¹⁰
Weight-loss marketing was challenged by the FTC. In 2014 the US FTC settled with the company that sold a green coffee extract, saying its weight-loss claims rested on a seriously flawed study, and the company agreed to pay $3.5 million. Authoritative guidance ²⁶
Not enough is known for pregnancy and breastfeeding. RxList advises avoiding green coffee in pregnancy and breastfeeding because reliable information is insufficient. EFSA says up to 200 mg of caffeine a day from all sources is not a concern for the foetus; green coffee extract itself was not studied in pregnancy in the sources read. A Cochrane review (2015) found only one trial with data on cutting caffeine in pregnancy (cutting about 182 mg a day made no clear difference to birthweight) and called the evidence insufficient either way. Authoritative guidance ^{24 7 13}

Side effects 4

Effect	How often	Severity and recovery	Evidence
Insomnia, nervousness, restlessness, upset stomach, nausea, vomiting, faster heartbeat and breathing Listed by RxList as caffeine-related. No frequency given.	Not established	mild to moderate Not stated	Authoritative guidance ²⁴
Headache, anxiety, agitation, ringing in the ears, irregular heartbeat with larger amounts RxList describes these with large amounts. No numbers given.	Not established	moderate Not stated	Authoritative guidance ²⁴
Higher blood homocysteine after high amounts of pure chlorogenic acid Healthy volunteers who took 2 g of chlorogenic acid daily for 7 days had 12% higher homocysteine 4-5 hours after intake and 4% higher in fasting blood. The authors say it is not known whether this changes heart disease risk.	Not established	unknown Not tested	Controlled trial ¹⁹
No adverse events reported in small blood pressure and pharmacokinetic trials Onakpoya 2015: all 5 trials reported no adverse events. Watanabe 2006: no apparent side effects in 28 adults. Morton 2018: none in 16 men after one dose. These trials were small and short.	Not established	none reported not applicable	Controlled trial ^{21 28 17}

Liver

We found no LiverTox entry specific to green coffee extract (the LiverTox pages could not be opened in this session, so absence of an entry is not confirmed). A Slovenian case series of 4 patients with 5 episodes of liver injury involved fat-burner products including green coffee beans, green tea extract, Garcinia gummi-gutta and spirulina; liver biopsy found no other cause, and one patient needed a liver transplant. Because each patient took different products and the abstract does not say who took green coffee, the series cannot show that green coffee caused the injury. RxList does not mention liver effects. ¹⁰

How often. No frequency is given in the sources read.

Monitoring. No agency monitoring advice for green coffee was found. If you have liver disease or notice dark urine, yellow skin or eyes, or pain under the right ribs, stop and seek care.

p29310849. 4 patients, 5 episodes: acute liver failure with transplant (1), acute hepatitis that resolved (1), severe bleeding after liver biopsy (1), two separate episodes with two products (1). Products: green tea extract, Garcinia gummi-gutta, green coffee beans, spirulina.

This is a safety connection. It is not evidence that Green Coffee Bean Extract supports liver health.

Medicines and supplements 7

With	Why it matters	Importance	Evidence	What to do
Diabetes medicines blood-sugar	Caffeine can raise or lower blood sugar. A 9-person study found caffeinated coffee raised early glucose and insulin. Chlorogenic acid might slow sugar absorption.	RxList rates this minor and says the diabetes drug dose may need adjusting. It is based on caffeine and theory, not on green coffee trials.	Pharmacological theory Low certainty ^{24 15}	Tell your doctor or pharmacist before use and check blood sugar as advised.
Blood pressure medicines blood-pressure	The extract may lower blood pressure a little; caffeine can raise it.	RxList rates this minor: green coffee may lower blood pressure too much. Not shown in trials with medicine.	Pharmacological theory Low certainty ^{24 25}	Ask your doctor or pharmacist; monitor blood pressure.
Blood thinners and antiplatelets (warfarin, aspirin) anticoagulant	Caffeine may slow clotting, in theory.	RxList rates this moderate and says it may raise bruising and bleeding risk. No case of this with green coffee was found in the sources read; treat it as a theory.	Pharmacological theory Very low certainty ²⁴	Tell your prescriber before use.
Drugs that block CYP1A2 (fluvoxamine, mexiletine, clozapine, theophylline, quinolone antibiotics, disulfiram, cimetidine and others) caffeine-metabolism	These drugs slow the breakdown of caffeine, so caffeine levels stay higher. Carrillo and Benitez (2000) review this for dietary caffeine and note toxic effects can include seizures, delirium and arrhythmia.	RxList lists most of these as moderate. Based on caffeine, not green coffee studies.	Authoritative guidance Moderate certainty ^{3 24}	Ask your pharmacist whether caffeine is a problem with your medicines.
Other stimulants (ephedrine, pseudoephedrine, phentermine, MAOIs, asthma beta-agonists) stimulants	Added stimulation of the heart and nervous system.	RxList rates these moderate: risk of overstimulation, fast heartbeat and high blood pressure.	Authoritative guidance Low certainty ²⁴	Avoid combining unless your doctor agrees.
Lithium, adenosine and dipyridamole stress tests, alendronate, estrogens, birth control pills other	Caffeine can change lithium clearance, block heart stress-test drugs, or be cleared more slowly with estrogens; RxList says green coffee may reduce alendronate absorption.	Rated moderate or minor by RxList; mechanisms are from caffeine.	Authoritative guidance Low certainty ²⁴	Tell your doctor or pharmacist; stop caffeine before a stress test if told to.
Iron from food and supplements nutrient	Chlorogenic acid and other polyphenols in coffee cut absorption of non-haem iron. Hurrell 1999 found coffee, tea, cocoa and herb teas all cut iron absorption from a bread meal in a dose-dependent way.	That trial used brewed drinks and a single meal, not green coffee capsules. The effect on iron levels in people who take the extract has not been studied in the sources read.	Controlled trial Low certainty ¹²	If you are low in iron or take iron, take it at a different time from coffee products and ask your doctor or pharmacist.

Who should check first 4

Situation	Advice	Evidence
Pregnancy and breastfeeding	RxList advises avoiding; reliable information is insufficient.	Authoritative guidance ^{24 7}
Caffeine-sensitive conditions: anxiety, abnormal heart rhythm, high blood pressure, glaucoma, bleeding disorders, diarrhoea or irritable bowel, osteoporosis	RxList lists these as conditions for caution because of caffeine. Use only if your doctor agrees.	Authoritative guidance ²⁴
Liver disease or a past liver reaction to a supplement	Avoid fat-burner products; the case series shows serious liver injury can occur with such products.	Case series ¹⁰
High homocysteine	RxList lists a caution because high-dose chlorogenic acid raised homocysteine in a short trial.	Controlled trial ^{24 19}

Overdose, product quality and regulators

Summary. No toxic dose of green coffee extract was found in the sources read. The main concerns are caffeine and the liver reports above.

Animal. No animal safety study was read for this profile.

Human doses studied. Trial amounts vary and are not listed here. Reviewers report no adverse events in small trials.

High dose or long term signals. Pure chlorogenic acid at 2 g a day raised homocysteine over 7 days. No long-term (over 12 weeks) safety data were found in the sources read; RxList says extracts have been used up to 12 weeks.

Overdose response. Caffeine toxicity can include seizures, delirium and arrhythmia (Carrillo and Benitez 2000).

Genotoxicity. Not found.

Toxic plant parts. Not applicable; the seed (green bean) is the part used.

No contamination or adulteration study of green coffee extract products was found.

. Caffeine in green Coffea arabica beans varies with origin; roasting did not change it much. ²

. The FTC action concerned marketing claims, not contamination. ²⁶

Body	Action	Date
US Federal Trade Commission (United States)	Settlement with Applied Food Sciences over green coffee weight-loss claims: $3.5 million; future weight-loss claims need at least two adequate, well-controlled human trials. source	2014-09-01
EFSA (European Food Safety Authority) (European Union)	2015 opinion on caffeine from all sources: up to 200 mg per dose and 400 mg a day not a concern for healthy adults; up to 200 mg a day in pregnancy not a concern for the foetus. Not specific to green coffee. source	2015-05-27

When to get medical help

Yellow skin or eyes, dark urine, or pain under the right ribs (liver).
Chest pain, a racing or irregular heartbeat, fainting, or a severe headache.
Seizures or confusion.
Unusual bleeding or bruising if you take blood thinners.

Stop the supplement and contact a clinician or emergency service. In the US, Poison Control is 1-800-222-1222.

General information only, not medical advice. Ask a clinician or pharmacist before use, especially with medicines, in pregnancy or with a health condition. See the Natural Remedy Safety guide.

Frequently asked questions

What is green coffee bean extract?

It is an extract of unroasted coffee seeds from Coffea arabica or C. canephora, rich in chlorogenic acids. Many products also contain caffeine unless labelled decaffeinated.

^{8 9 18}

Does green coffee extract help you lose weight?

Pooled small trials show average weight losses of about 1 to 2.5 kg in favourable analyses, and one large analysis found no significant weight change. Reviewers call the trials few, short and often poor quality.

^{20 11 16 30}

What happened to the famous green coffee weight-loss study?

A 2012 trial that reported large weight loss was retracted in 2014. The FTC said the study was so flawed no reliable conclusions could be drawn, and the company that sold the extract settled for $3.5 million.

^{27 6 26}

Does it lower blood pressure?

A 2024 pooled analysis of 10 studies found about 3 mmHg lower systolic and 2 mmHg lower diastolic pressure. The trials are small and several were funded by chlorogenic acid makers. Caffeine can raise blood pressure in some people.

^{25 21 24}

Does it help with blood sugar or diabetes?

Fasting glucose was only about 2 mg/dL lower in pooled data and HbA1c did not change. No trial in people with diagnosed diabetes was found. Ask your doctor or pharmacist if you take diabetes medicine.

^{4 22 24}

How much caffeine is in it?

The sources we read do not give a caffeine amount for green coffee products. Check the label. EFSA says up to 400 mg a day from all sources is not a concern for healthy adults.

^{24 7 2}

Can it harm the liver?

A case series linked fat-burner supplements that included green coffee beans, green tea extract, Garcinia and spirulina to liver injury, with one liver transplant. Green coffee could not be singled out. No LiverTox entry for green coffee was found.

¹⁰

Does it interact with medicines?

Mostly through caffeine. RxList lists interactions with drugs that slow caffeine breakdown, other stimulants, lithium, blood thinners (theory), diabetes drugs and blood pressure drugs. These are mostly theory, not green coffee trials. Ask your pharmacist.

^{24 3}

Does it affect iron?

Coffee polyphenols reduced non-haem iron absorption in a meal study with brewed drinks. This has not been studied with the extract. If you are low in iron, ask your doctor or pharmacist about timing.

¹²

Is it safe in pregnancy or breastfeeding?

RxList advises avoiding it because reliable information is insufficient. EFSA says up to 200 mg of caffeine a day from all sources is not a concern for the foetus; the extract itself was not studied in pregnancy.

^{24 7 13}

Is green coffee as a drink as good as the extract?

A network meta-analysis found coffee, decaffeinated coffee and green coffee drinks did not reduce weight, while green tea gave a small loss.

¹⁴

Does the EMA or NCCIH recommend it?

We found no EMA/HMPC monograph and no NCCIH page for green coffee. Absence of a page does not prove either body has taken a position.

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Editorial transparency

Written by: AlternativeMed editorial team. Research compiled with AI assistance, then checked against PubMed records.
Medical review: None. This page has not been reviewed by a physician or pharmacist.
First published: 2026-10-25
Last substantive update: 2026-10-25
How we research: We searched PubMed, read the US FTC release, the RxList green coffee page and the EFSA caffeine page, and recorded each study design and limits. Pages that could not be opened are marked not read.
How we rate evidence: See "How we rate evidence" in the Evidence tab.
Independence: No product is promoted on this page. No affiliate links are shown.

Sources 30

Each source was opened and checked. Where we read only the abstract, it says so. The small numbers in the text point here.

Asbaghi O, Sadeghian M, Nasiri M, et al.. The effects of green coffee extract supplementation on glycemic indices and lipid profile in adults: a systematic review and dose-response meta-analysis of clinical trials.. Nutr J. 2020. PMID 32665012. DOI 10.1186/s12937-020-00587-z. (abstract)
Bobková A, Demianová A, Poláková K, et al.. Variability of caffeine content in green and roasted Coffea arabica regarding the origin, post-harvest processing, and altitude, and overview of recommended daily allowance.. J Environ Sci Health B. 2022. PMID 36573489. DOI 10.1080/03601234.2022.2159739. (abstract)
Carrillo JA, Benitez J. Clinically significant pharmacokinetic interactions between dietary caffeine and medications.. Clin Pharmacokinet. 2000. PMID 10976659. DOI 10.2165/00003088-200039020-00004. (abstract)
Chen Y, Zhao Y, Wang Y, et al.. The influence of green coffee bean extract supplementation on blood glucose levels: A systematic review and dose-response meta-analysis of randomized controlled trials.. Phytother Res. 2020. PMID 32159261. DOI 10.1002/ptr.6667. (abstract)
Chen H, Huang W, Huang X, et al.. Effects of green coffee bean extract on C-reactive protein levels: A systematic review and meta-analysis of randomized controlled trials.. Complement Ther Med. 2020. PMID 32951749. DOI 10.1016/j.ctim.2020.102498. (abstract)
. Randomized, double-blind, placebo-controlled, linear dose, crossover study to evaluate the efficacy and safety of a green coffee bean extract in overweight subjects [Retraction].. Diabetes Metab Syndr Obes. 2014. PMID 25340633. DOI 10.2147/DMSO.S75357. (summary-only)
European Food Safety Authority. Scientific Opinion on the safety of caffeine (EFSA topic page). EFSA. 2015. (summary-only)
GBIF. GBIF Backbone: Coffea arabica L.. GBIF species API. 2026. (full-text)
GBIF. GBIF Backbone: Coffea canephora Pierre ex A.Froehner. GBIF species API. 2026. (full-text)
Gavrić A, Ribnikar M, Šmid L, et al.. Fat burner-induced acute liver injury: Case series of four patients.. Nutrition. 2018. PMID 29310849. DOI 10.1016/j.nut.2017.10.002. (abstract)
Gorji Z, Varkaneh HK, Talaei S, et al.. The effect of green-coffee extract supplementation on obesity: A systematic review and dose-response meta-analysis of randomized controlled trials.. Phytomedicine. 2019. PMID 31398662. DOI 10.1016/j.phymed.2019.153018. (abstract)
Hurrell RF, Reddy M, Cook JD. Inhibition of non-haem iron absorption in man by polyphenolic-containing beverages.. Br J Nutr. 1999. PMID 10999016. (abstract)
Jahanfar S, Jaafar SH. Effects of restricted caffeine intake by mother on fetal, neonatal and pregnancy outcomes.. Cochrane Database Syst Rev. 2015. PMID 26058966. DOI 10.1002/14651858.CD006965.pub4. (abstract)
Jayedi A, Norouziasl R, Aletaha A, et al.. Comparative effects of tea and coffee drinking on body weight in adults: a systematic review and network meta-analysis of randomised trials.. Br J Nutr. 2024. PMID 39497467. DOI 10.1017/S0007114524001867. (abstract)
Johnston KL, Clifford MN, Morgan LM. Coffee acutely modifies gastrointestinal hormone secretion and glucose tolerance in humans: glycemic effects of chlorogenic acid and caffeine.. Am J Clin Nutr. 2003. PMID 14522730. DOI 10.1093/ajcn/78.4.728. (abstract)
Kanchanasurakit S, Saokaew S, Phisalprapa P, et al.. Chlorogenic acid in green bean coffee on body weight: a systematic review and meta-analysis of randomized controlled trials.. Syst Rev. 2023. PMID 37710316. DOI 10.1186/s13643-023-02311-4. (abstract)
Morton K, Knight K, Kalman D, et al.. A Prospective Randomized, Double-Blind, Two-Period Crossover Pharmacokinetic Trial Comparing Green Coffee Bean Extract-A Botanically Sourced Caffeine-With a Synthetic USP Control.. Clin Pharmacol Drug Dev. 2018. PMID 29659178. DOI 10.1002/cpdd.451. (abstract)
NCBI PubChem. PubChem compound records: chlorogenic acid, caffeine, caffeic acid, quinic acid, trigonelline. PubChem. 2026. (full-text)
Olthof MR, Hollman PC, Zock PL, et al.. Consumption of high doses of chlorogenic acid, present in coffee, or of black tea increases plasma total homocysteine concentrations in humans.. Am J Clin Nutr. 2001. PMID 11237928. DOI 10.1093/ajcn/73.3.532. (abstract)
Onakpoya I, Terry R, Ernst E. The use of green coffee extract as a weight loss supplement: a systematic review and meta-analysis of randomised clinical trials.. Gastroenterol Res Pract. 2011. PMID 20871849. DOI 10.1155/2011/382852. (abstract)
Onakpoya IJ, Spencer EA, Thompson MJ, et al.. The effect of chlorogenic acid on blood pressure: a systematic review and meta-analysis of randomized clinical trials.. J Hum Hypertens. 2015. PMID 24943289. DOI 10.1038/jhh.2014.46. (abstract)
Pourmasoumi M, Hadi A, Marx W, et al.. The Effect of Green Coffee Bean Extract on Cardiovascular Risk Factors: A Systematic Review and Meta-analysis.. Adv Exp Med Biol. 2021. PMID 34981487. DOI 10.1007/978-3-030-73234-9_21. (abstract)
Roshan H, Nikpayam O, Sedaghat M, et al.. Effects of green coffee extract supplementation on anthropometric indices, glycaemic control, blood pressure, lipid profile, insulin resistance and appetite in patients with the metabolic syndrome: a randomised clinical trial.. Br J Nutr. 2018. PMID 29307310. DOI 10.1017/S0007114517003439. (abstract)
RxList. Green Coffee: Health Benefits, Side Effects, Uses, Dose and Precautions. RxList (consumer drug reference). 2026. (full-text)
Samavat S, Ashtary-Larky D, Naeini F, et al.. The effects of green coffee bean extract on blood pressure and heart rate: A systematic review and dose-response meta-analysis of randomized controlled trials.. Diabetes Metab Syndr. 2024. PMID 39368321. DOI 10.1016/j.dsx.2024.103120. (abstract)
US Federal Trade Commission. Green coffee bean manufacturer settles FTC charges of pushing its product based on results of a seriously flawed study. FTC press release. 2014. (full-text)
Vinson JA, Burnham BR, Nagendran MV. Randomized, double-blind, placebo-controlled, linear dose, crossover study to evaluate the efficacy and safety of a green coffee bean extract in overweight subjects.. Diabetes Metab Syndr Obes. 2012. PMID 22291473. DOI 10.2147/DMSO.S27665. (abstract)
Watanabe T, Arai Y, Mitsui Y, et al.. The blood pressure-lowering effect and safety of chlorogenic acid from green coffee bean extract in essential hypertension.. Clin Exp Hypertens. 2006. PMID 16820341. DOI 10.1080/10641960600798655. (abstract)
Wiyarta E, Budiman RA, Subroto DRT, et al.. Plant-Derived Natural Products for Dietary Intervention in Overweight and Obese Individuals: A Systematic Review and Network Meta-Analysis.. Phytother Res. 2025. PMID 40420357. DOI 10.1002/ptr.8490. (abstract)
Yang Z, Shao Z, Ouyang W, et al.. The effect of green coffee extract supplementation on obesity indices: critical umbrella review of interventional meta-analyses.. Crit Rev Food Sci Nutr. 2024. PMID 37341701. DOI 10.1080/10408398.2023.2225614. (abstract)

Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.