Sulforaphane and Glucosinolates in Cruciferous Vegetables
How glucosinolates in broccoli and other crucifers form sulforaphane, what cooking does, what human studies show so far, and why raw sprouts carry a food-safety warning.
Content last updated . This page has not been medically reviewed.
Safety first. Natural products can cause side effects and interact with medicines. Read functional food safety before you use anything on this page.
Food-safety point first: raw sprouts, including broccoli and alfalfa sprouts, can carry bacteria. A 2025 review notes that the warm, humid, nutrient-rich conditions of sprout growing favor pathogens such as Salmonella enterica, Escherichia coli and Listeria monocytogenes. [1] Official advice on who should avoid raw sprouts is on the raw sprouts, raw milk and undercooked foods page. We could not read the FDA or CDC sprout pages this session, so we do not restate their advice here. If you have severe symptoms after eating, see when to seek medical help after a food reaction.
Short answer: Broccoli and other crucifers (cabbage-family vegetables such as Brassica oleracea) contain glucosinolates. [2] One of them, glucoraphanin, can be converted to sulforaphane. Most of what is known about sulforaphane comes from laboratory and small human studies of how it forms and is absorbed, not from trials of disease outcomes.
How sulforaphane forms
A review explains that eating broccoli releases sulforaphane when the plant enzyme myrosinase (or gut bacteria) breaks down glucoraphanin. Both sulforaphane and plant myrosinase are sensitive to heat, and another plant protein can steer the reaction toward a different compound, sulforaphane nitrile. [3]
What the studies found
| Question | What the source found | Strength of evidence |
|---|---|---|
| Cooking and sulforaphane | In a laboratory study, myrosinase activity fell by 80 percent after 3 minutes of stir-frying; letting broccoli's glucosinolates break down for 90 minutes before stir-frying gave 2.8 times more sulforaphane. [4] | Preclinical (food chemistry) |
| Absorption in people | A crossover trial of 18 people compared a diet with no broccoli to 15 days of cooked broccoli plus raw daikon radish. Metabolites in blood and urine differed by body mass index. [5] | Insufficient evidence (very small, a marker study) |
| Disease outcomes from eating crucifers | Proper evidence not found here. We searched PubMed for sulforaphane and broccoli trials; results were mostly supplement or extract trials that we did not read, so no food-level outcome claim is made. | Insufficient evidence |
The two cooking and absorption findings describe how the compound behaves. They are not advice on how to cook, and they say nothing about preventing disease.
Food versus supplement
Broccoli, broccoli sprouts and "sulforaphane" or "glucoraphanin" capsules and powders are different products. A supplement trial does not describe eating broccoli, and the reverse is also true. For capsule quality, see quality testing and certifications.
Frequently asked questions
Is sulforaphane in broccoli itself?
Not as such. A review explains that it forms from glucoraphanin by the enzyme myrosinase or by gut bacteria. [3]
Does cooking destroy it?
A review says sulforaphane and myrosinase are heat-sensitive. [3] A laboratory stir-frying study found myrosinase activity fell sharply within minutes. [4]
Do broccoli sprouts have more?
Proper evidence not found in what we read; we did not read a source comparing sprouts with mature broccoli. Raw sprouts also carry a bacteria risk. [1]
Does sulforaphane prevent cancer?
We did not find a food-level trial of cancer outcomes in what we read, so no such claim is made.
Are capsules the same as eating broccoli?
No. They are different products, and a trial of one does not transfer to the other.
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 and who should ask a clinician
- Thyroid questions, and everyday cruciferous vegetables: see the broccoli and cruciferous vegetables page.
- Medicines: the sources we read did not describe interactions of crucifers or sulforaphane. Ask a pharmacist, especially about concentrated products, and see How Interactions Work.
- Pregnancy, breastfeeding, children, older adults and people with weakened immunity: raw sprouts are a food-safety issue; the sources we read for this page did not give group-specific advice, so ask a clinician.
References
- Understanding food safety on sprouts and microgreens: Contamination routes, outbreaks and challenges. Food Res Int 2025. PMID 40467198. Read 2026-10-23.
- GBIF Backbone Taxonomy species match. Global Biodiversity Information Facility. Accepted names checked 2026-10-23.
- Approaches for enhancing the stability and formation of sulforaphane. Food Chem 2021. PMID 33601652. Read 2026-10-23.
- Hydrolysis before Stir-Frying Increases the Isothiocyanate Content of Broccoli. J Agric Food Chem 2018. PMID 29357241. Read 2026-10-23.
- Absorption and metabolism of isothiocyanates formed from broccoli glucosinolates: effects of BMI and daily consumption in a randomised clinical trial. Br J Nutr 2018. PMID 30499426. Read 2026-10-23.