Nuts and Seeds for Heart Health: What Trials Found
What reviews of cohort studies and trials found about nuts and seeds, cholesterol, heart disease and body weight, and what the evidence cannot show.
Content last updated . This page has not been medically reviewed.
Safety first. Supplements can cause side effects and interact with medicines. Read mushroom safety and interactions before you use any mushroom product.
How the sources define the question
Nuts here means tree nuts such as walnuts and almonds. Some of the reviews below also include peanuts (a legume) or seeds. Where a review mixes them, the text says so. Results for whole nuts do not apply to nut butters, oils or supplements, which these studies did not test.What research found
| Question | What the source found | Strength of evidence | Design |
|---|---|---|---|
| Heart disease and death, by intake | A review of 20 cohort studies found each 28 g a day of nuts linked to lower risk of coronary heart disease (RR 0.71), cardiovascular disease (0.79) and all-cause death (0.78). The stroke link was not clear (0.93, CI 0.83 to 1.05). Results were similar for tree nuts and peanuts. [3] | Promising but limited (observational) | Prospective cohorts |
| Nuts and seeds together | A 2023 review of 28 cohorts and 18 trials found high versus low intake linked to lower cardiovascular disease (RR 0.81) and coronary heart disease (RR 0.82). The authors rated the link "probable" and called for more research on specific nuts. [4] | Promising but limited | Cohorts and trials of 12 weeks or more |
| LDL cholesterol | A review of 61 trials in adults without heart disease found each serving (28.4 g) a day lowered LDL by 4.8 mg/dL and total cholesterol by 4.7 mg/dL. Effects were larger at 60 g a day or more and depended more on amount than on nut type. [5] | Established as a small average effect on cholesterol; clinical outcomes not shown by these trials | Trials of 3 to 26 weeks |
| Blood pressure | The 2023 review found no change in blood pressure from nuts. [4] | No good evidence of benefit | Trials |
| Heart events in a trial | In PREDIMED, a Mediterranean diet with mixed nuts had a hazard ratio of 0.72 (95% CI 0.54 to 0.95) for major cardiovascular events versus a reduced-fat control diet. [6] | Promising but limited | 7,447 people at high risk; first report withdrawn and revised |
| Body weight | A review of 55 trials found nut diets did not change body weight, BMI or waist size. [7] | Established for no weight change in trials of 3 weeks or longer | Trials |
| Seeds alone | Proper evidence not found. We read no review that separated seeds from nuts for heart outcomes. | Insufficient evidence | See flaxseed, chia and pumpkin seeds |
Frequently asked questions
Do nuts lower cholesterol?
On average, a little. A review of 61 trials found about 4.8 mg/dL lower LDL per daily serving. [5]
Do nuts prevent heart attacks?
Cohort studies link nut intake to lower heart disease risk, but that is association. [3] Proper evidence from trials that nuts alone prevent heart attacks was not found in the sources we read.
Do nuts cause weight gain?
A review of 55 trials found no change in body weight, BMI or waist size. [7]
Are seeds as well studied as nuts?
Not in what we read. One review combined nuts and seeds. [4] Proper evidence on seeds alone was not found.
Who should avoid nuts?
People with a nut allergy. Tree nut allergies tend to last a lifetime, so ask an allergy clinician. [1]
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Safety first: allergy
Tree nuts are among the common food allergens, and these allergies tend to last a lifetime. [1] Walnuts, almonds, hazelnuts, pecans, cashews, pistachios and Brazil nuts are all tree nuts. [2] Call 911 for trouble breathing, or swelling of the lips, mouth or throat. See food allergy basics and emergency signs and food safety for babies and toddlers for choking questions.
Limits and uncertainty
- Cohort studies show association, not cause. People who eat nuts may differ in other habits. See observational studies versus trials.
- Cholesterol is a marker. The trials measured blood tests, not heart attacks. The only trial with heart events used a whole dietary pattern. [6]
- The PREDIMED authors withdrew their original 2013 report after finding protocol deviations. [6]
- The FDA lists qualified health claims about nuts and coronary heart disease, including entries dated 2003 for nuts and 2004 for walnuts. We read titles and dates only, not the wording. [8]
Who should ask a clinician
People with any nut or seed allergy, and caregivers of young children, should ask about choking and allergy before offering whole nuts. People with kidney disease, those on special diets, and anyone taking medicines should ask a pharmacist or clinician about specific nuts. Brazil nuts have a selenium upper limit; see other nuts. Related: walnuts, almonds, pistachios and foods for cholesterol and heart health.
References
- MedlinePlus. Food allergy. Read 2026-10-23.
- NHS (UK). Food allergy. Read 2026-10-23.
- Aune D et al. Nut consumption and risk of cardiovascular disease, total cancer, all-cause and cause-specific mortality: a systematic review and dose-response meta-analysis of prospective studies. BMC Med 2016. PMID 27916000. Read 2026-10-23 (abstract via Europe PMC).
- Nuts and seeds consumption and risk of cardiovascular disease, type 2 diabetes and their risk factors: a systematic review and meta-analysis. Food Nutr Res 2023. Read 2026-10-23 (abstract via Europe PMC).
- Del Gobbo LC et al. Effects of tree nuts on blood lipids, apolipoproteins, and blood pressure: systematic review, meta-analysis, and dose-response of 61 controlled intervention trials. Am J Clin Nutr 2015. PMID 26561616. Read 2026-10-23 (abstract via Europe PMC).
- Estruch R et al. Primary Prevention of Cardiovascular Disease with a Mediterranean Diet Supplemented with Extra-Virgin Olive Oil or Nuts. N Engl J Med 2018. PMID 29897866. Read 2026-10-23.
- Intake of Nuts or Nut Products Does Not Lead to Weight Gain, Independent of Dietary Substitution Instructions: A Systematic Review and Meta-Analysis of Randomized Trials. Adv Nutr 2021. Read 2026-10-23 (abstract via Europe PMC).
- U.S. Food and Drug Administration. Qualified Health Claims: Letters of Enforcement Discretion (list of claim titles and dates; letters not read). Read 2026-10-23.
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.