Sulforaphane Benefits: What the Evidence Shows

Quick answer

Sulforaphane benefits, in short: Sulforaphane is a compound that forms when you chop or chew broccoli and other cruciferous vegetables, and it is especially concentrated in broccoli sprouts. Supplements usually supply its precursor, glucoraphanin, sometimes with an enzyme (myrosinase) that turns it into sulforaphane. The most-discussed human research is on blood sugar, and it is mixed: one early trial in people with type 2 diabetes reported lower fasting glucose and HbA1c [1], but a later 12-week trial in prediabetes missed its main target [2] and one in people with diabetes and kidney disease found no difference [3]. A trial in China showed higher excretion of some pollutant by-products, which is a lab marker, not a health outcome [4]. We rate the evidence D: small trials, mixed results, and nothing showing it helps you live longer.

What is sulforaphane?

Broccoli contains glucoraphanin, a stable “precursor”. When the vegetable is cut or chewed, an enzyme called myrosinase converts it into sulforaphane. If the enzyme is not active (for example, in a heat-treated extract), gut bacteria may do part of the conversion instead [2][5]. This varies from person to person [2]. In one small study, sulforaphane from preparations with active myrosinase was 3 to 4 times more bioavailable than from glucoraphanin alone [5]. So what a label says (glucoraphanin versus sulforaphane, and whether it has active myrosinase) matters.

Sulforaphane benefits: what might it help with?

Possible benefit	Rating	In plain words
Blood sugar in type 2 diabetes	Mixed	One trial reported improvements [1]. A trial in people with kidney disease and diabetes found none [3]
Blood sugar in prediabetes	Mixed	A 12-week trial missed its main target. Benefits were seen mainly in a subgroup [2]
Detox enzyme activity (lab marker)	Promising	Higher excretion of some pollutant by-products in a 12-week trial of 291 adults [4]. This is a marker, not a proven health benefit
Living longer or “slowing aging”	Early	No human trial has tested this

Ratings describe how good the research is, not a promise that it will work for you.

What the research says

• Type 2 diabetes. In a 2017 study, sulforaphane reduced liver glucose production in cells and animals. In obese people with poorly controlled type 2 diabetes, a concentrated broccoli sprout extract reduced fasting blood glucose and HbA1c [1]. PubMed
• Prediabetes. In a 2025 trial of 74 adults, 12 weeks of broccoli sprout extract did not meet the main goal (a 0.3 mmol/l drop in fasting glucose). The average drop was 0.2 mmol/l. Some people with certain traits had bigger drops, linked to their gut bacteria. Stomach and gut side effects occurred [2]. PubMed
• Diabetes with kidney disease. In 99 adults, 12 weeks of broccoli sprout extract did not change fasting glucose, insulin or HbA1c compared with placebo [3]. PubMed
• Air pollution, China. In 291 adults living in a polluted area, a broccoli sprout drink (600 µmol glucoraphanin and 40 µmol sulforaphane a day) raised urinary excretion of benzene by-products by 61% and acrolein by-products by 23% compared with placebo [4]. PubMed
• Bioavailability. Preparations with active myrosinase gave 3 to 4 times more sulforaphane than glucoraphanin delivered without it, in a small group of volunteers [5]. PubMed

Amounts and how people take it

These are amounts used in studies, not recommendations.

• Form: capsules or powders of broccoli sprout or seed extract (glucoraphanin), sometimes with added myrosinase. Fresh broccoli sprouts are another option.
• Amounts in trials: these vary widely, from a drink providing 40 µmol of sulforaphane and 600 µmol glucoraphanin [4] to up to 150 µmol of extract a day in the kidney disease trial [3]. Doses are not standard across products.
• Length: the longest trials we cite lasted about 12 weeks, so long-term effects are unknown.

Side effects, interactions and who should check first

What trials found

In the prediabetes trial, there were gut side effects but no severe adverse events [2]. Digestive upset is a possibility with concentrated extracts.

Thyroid. Cruciferous vegetables have been suspected of affecting the thyroid. A 2024 review of 123 studies found most results do not support anti-thyroid effects in people, particularly with adequate iodine intake [6]. If you have a thyroid condition, check with your doctor first, since this review covered foods and extracts, not every supplement.

Medicines. In lab and animal studies, isothiocyanates can affect liver enzymes that process medicines. Sulforaphane appeared to need high doses to do this, and the effect at supplement doses in people is unknown [7].

Who should check with a doctor or pharmacist first

Check with a doctor or pharmacist first if you:

• take any regular medicine, especially diabetes medicines, since sulforaphane may lower blood sugar and we did not find trials testing the combination
• have a thyroid condition or kidney disease
• are pregnant, breastfeeding or trying to conceive, or are under 18. We found no reliable safety data in these groups
• have a long-term health condition, or a sensitive stomach.

Where to buy

Look for a label that states whether the product contains glucoraphanin or sulforaphane and the amount per daily serving, whether it includes active myrosinase, evidence of third-party testing, and compare products by price per daily dose rather than pack price.

FAQ

What is sulforaphane?

Sulforaphane is a compound that forms when you chop or chew broccoli and other cruciferous vegetables, and it is especially concentrated in broccoli sprouts. Supplements usually supply its precursor, glucoraphanin, sometimes with an enzyme (myrosinase) that turns it into sulforaphane [2][5]. Check which one a label contains.

Does sulforaphane work?

The results are mixed, and the human research is thin. One early trial in people with type 2 diabetes reported lower fasting glucose and HbA1c [1], but a 12-week prediabetes trial missed its main target [2] and a trial in people with diabetes and kidney disease found no difference [3]. No human trial has tested whether it helps you live longer. We rate the evidence C.

How much sulforaphane per day?

Amounts vary widely and aren’t standard across products. Studies used a drink providing 40 µmol of sulforaphane and 600 µmol of glucoraphanin a day [4] and up to 150 µmol of extract a day in the kidney disease trial [3]. The longest trials lasted about 12 weeks. These are amounts used in studies, not recommendations.

Who should not take sulforaphane?

Check with a doctor or pharmacist first if you take any regular medicine, especially diabetes medicines, have a thyroid condition or kidney disease, are pregnant, breastfeeding, trying to conceive or under 18, have a long-term condition, or have a sensitive stomach. A 2024 review found most results do not support anti-thyroid effects in people [6], but it covered foods and extracts, not every supplement.

Can you take sulforaphane with other supplements?

We found no trials testing sulforaphane alongside other supplements, so we can’t say whether combinations are safe or useful. In lab and animal studies, isothiocyanates can affect liver enzymes that process medicines, but the effect at supplement doses in people is unknown [7]. Ask a doctor or pharmacist before combining it with anything.

Related pages

• Apigenin
• Quercetin
• Resveratrol
• Longevity supplements for beginners: where this fits in a beginner’s routine
• All supplements A-Z

Talk to your doctor

This page is for general information and is not medical advice. Speak to a doctor or pharmacist before starting any supplement, especially if you are pregnant or breastfeeding, take any medicine, or have a health condition.

References

We cite only studies and official pages we checked against PubMed, the publisher or the agency’s own site. The A to E evidence grades are explained in our editorial policy. See also our medical disclaimer and affiliate disclosure.

1. Axelsson AS, Tubbs E, Mecham B, Chacko S, et al. Sulforaphane reduces hepatic glucose production and improves glucose control in patients with type 2 diabetes. Sci Transl Med. 2017. PubMed · DOI
2. Dwibedi C, Axelsson AS, Abrahamsson B, Fahey JW, et al. Effect of broccoli sprout extract and baseline gut microbiota on fasting blood glucose in prediabetes: a randomized, placebo-controlled trial. Nat Microbiol. 2025. PubMed · DOI
3. Avesani CM, Swartling O, Rosengren AH, Heimbürger O, et al. Broccoli Sprout Extract for Glycemic Management in Patients with Chronic Kidney Disease and Type 2 Diabetes: A Randomized Double-Blind Placebo-Controlled Trial. J Ren Nutr. 2026. PubMed · DOI
4. Egner PA, Chen JG, Zarth AT, Ng DK, et al. Rapid and sustainable detoxication of airborne pollutants by broccoli sprout beverage: results of a randomized clinical trial in China. Cancer Prev Res (Phila). 2014. PubMed · DOI
5. Fahey JW, Holtzclaw WD, Wehage SL, Wade KL, et al. Sulforaphane Bioavailability from Glucoraphanin-Rich Broccoli: Control by Active Endogenous Myrosinase. PLoS One. 2015. PubMed · DOI
6. Galanty A, Grudzińska M, Paździora W, Służały P, et al. Do Brassica Vegetables Affect Thyroid Function?-A Comprehensive Systematic Review. Int J Mol Sci. 2024. PubMed · DOI
7. Abdull Razis AF, Konsue N, Ioannides C. Isothiocyanates and Xenobiotic Detoxification. Mol Nutr Food Res. 2018. PubMed · DOI