Sulforaphane is a sulfur compound that forms when you chop or chew broccoli and other cruciferous vegetables. The plant stores it as an inactive precursor, glucoraphanin, and an enzyme called myrosinase turns it into sulforaphane. Broccoli sprouts carry far more glucoraphanin than mature broccoli, which is why they come up so often in aging research.
Sulforaphane is studied because it switches on a cell defense system called Nrf2. This guide covers where sulforaphane comes from, why cooking matters so much, what human studies have actually measured and what to look for on a supplement label.
Last reviewed: November 11, 2026
Key Takeaways
- Three-day-old broccoli sprouts had 10 to 100 times more glucoraphanin than mature broccoli plants in a 1997 study.
- In a 2008 study, raw crushed broccoli delivered about 37% of its sulforaphane potential to the body, compared with about 3.4% for cooked broccoli.
- Adding 1 g of powdered brown mustard to cooked broccoli raised sulforaphane uptake more than fourfold in a 2018 study.
- Turning up the Nrf2 pathway extended lifespan in male fruit flies, but no human trial has tested sulforaphane for aging.
- A small 2006 safety study of broccoli sprout extracts found no meaningful side effects over 7 days.
What is sulforaphane?
Sulforaphane is an isothiocyanate, a type of sulfur-containing plant compound. Broccoli doesn't hold much ready-made sulforaphane. It holds glucoraphanin, a stable precursor, along with the enzyme myrosinase. When the plant is chopped or chewed, myrosinase converts glucoraphanin into sulforaphane (Fahey et al., 1997).
Inside the body, sulforaphane is a potent trigger of "phase 2" enzymes. These are the body's own antioxidant and clearance enzymes, such as glutathione transferases, and they're controlled largely by the Nrf2 pathway. If glutathione is new to you, our guide to GlyNAC explains why researchers care about it in aging.
Which foods have the most sulforaphane?
Broccoli sprouts are the richest common food source of glucoraphanin. A 1997 study found that 3-day-old sprouts of certain broccoli and cauliflower cultivars contained 10 to 100 times more glucoraphanin than the mature plants (Fahey et al., 1997). Mature broccoli is the next best everyday source, and other cruciferous vegetables such as cauliflower, cabbage and kale contain related compounds in varying amounts.
How much sulforaphane you actually absorb depends less on the vegetable than on how you prepare and eat it.
Does cooking destroy sulforaphane?
Cooking doesn't destroy glucoraphanin, but heat inactivates myrosinase, the enzyme that turns it into sulforaphane. Without the plant's enzyme, your gut bacteria convert only a small share. That's why the same broccoli can deliver very different amounts:
| How it was eaten | What the study found | Study |
|---|---|---|
| 200 g raw broccoli, crushed | About 37% of the potential sulforaphane reached the body; blood levels peaked after about 1.6 hours | Vermeulen et al., 2008 (8 men) |
| 200 g cooked broccoli | About 3.4% reached the body; the peak was delayed to about 6 hours | Vermeulen et al., 2008 |
| 200 g cooked broccoli plus 1 g powdered brown mustard | More than four times as much sulforaphane metabolite in urine as cooked broccoli alone | Okunade et al., 2018 (12 adults) |
| Fresh sprouts chewed thoroughly vs swallowed whole | Chewing raised the amount recovered in urine from about 29 to 42 micromoles | Shapiro et al., 2001 |
Sources for the table: Vermeulen et al., 2008; Okunade et al., 2018; Shapiro et al., 2001.
The mustard trick works because mustard seeds carry their own active myrosinase. Mustard is a crucifer too, so a small spoonful of the powder stirred into cooked broccoli supplies the enzyme that cooking took away.
Why is sulforaphane linked to aging?
Sulforaphane is linked to aging mainly through the Nrf2 pathway, a master switch for the cell's stress defenses. In fruit flies, researchers found that switching off Keap1, the protein that holds Nrf2 in check, raised the flies' tolerance to oxidative stress and extended the lifespan of male flies (Sykiotis and Bohmann, 2008). That's a genetic result in insects, not a sulforaphane result in people.
Population studies point the same way but can't prove cause. In two Shanghai cohorts of 134,796 adults, people in the highest fifth of cruciferous vegetable intake had a 22% lower risk of death from any cause during follow-up than those in the lowest fifth (Zhang et al., 2011). People who eat a lot of vegetables tend to differ in many other ways, so this shows an association, not an effect of sulforaphane itself.
Turning on the body's own defenses, rather than adding outside antioxidants, is an example of what researchers call hormesis: a small, manageable stress that prompts a useful response (Mattson, 2008). For the bigger picture of what "healthy aging" means, see our guide to healthspan vs lifespan.
What have human sulforaphane studies measured?
The largest human trials measured how the body handles chemicals, not aging. In a 12-week randomized trial in Qidong, China, 291 adults living with heavy air pollution drank either a broccoli sprout beverage (600 micromoles of glucoraphanin and 40 micromoles of sulforaphane a day) or a placebo. The sprout group excreted 61% more of a benzene breakdown product and 23% more of an acrolein breakdown product in urine, meaning their bodies cleared more of two common air pollutants (Egner et al., 2014). Sulforaphane levels in urine also held steady across the 12 weeks.
That's a useful signal that sulforaphane does something measurable in people. It isn't evidence that sulforaphane slows aging or adds years, and no trial has tested that.
Is sulforaphane safe?
Broccoli sprouts are widely eaten, and researchers had seen no reported concerns about their tolerance before running a formal safety study. In that small placebo-controlled safety study, healthy volunteers took broccoli sprout extracts every 8 hours for 7 days (21 doses) at up to 100 micromoles of glucoraphanin or 25 micromoles of sulforaphane per dose. Researchers ran 32 blood and urine tests, including liver enzymes and hormone levels, and saw no significant or consistent adverse effects (Shapiro et al., 2006). With 12 volunteers (9 on extracts, 3 on placebo), that's reassuring for short-term use, not a long-term safety record.
Raw sprouts carry a separate food safety risk. The FDA notes that sprouts eaten raw or lightly cooked can carry bacteria such as Salmonella, Listeria and E. coli, because the warm, humid sprouting process also suits bacteria. Children, older adults, pregnant women and people with weakened immune systems are especially vulnerable to food poisoning (FDA). If that's you, mature broccoli with a pinch of mustard powder is a simpler route.
If you take prescription medication, are pregnant or breastfeeding, or are under medical care, ask your doctor or pharmacist before starting a concentrated sulforaphane or broccoli extract supplement.
What should you look for on a sulforaphane supplement label?
Sulforaphane supplements come in very different forms, and the label decides how much you're likely to absorb. A 2015 study found that sprout or seed powders that still had active myrosinase made sulforaphane 3 to 4 times more available than glucoraphanin given without the enzyme (Fahey et al., 2015). When comparing products, check:
- What's measured: glucoraphanin, sulforaphane or just "broccoli extract." A milligram amount for the extract alone doesn't tell you much.
- Whether myrosinase is included: glucoraphanin without the enzyme depends on your gut bacteria to convert it.
- Serving size: how many capsules the stated amount takes.
Our guide on how to read a Supplement Facts label walks through the rest of the panel.
OPA Nutrition All-in-One Greens
OPA Nutrition doesn't sell a sulforaphane or broccoli sprout supplement. Our All-in-One Greens powder includes kale, another cruciferous vegetable, in a 2,500 mg greens blend with wheat grass, spirulina and chlorella. It's an everyday greens powder, not a sulforaphane product, and the label doesn't list glucoraphanin or sulforaphane amounts.
How can you get more sulforaphane from food?
- Eat some broccoli raw or lightly cooked. Raw crushed broccoli delivered about ten times more sulforaphane than cooked broccoli in the 2008 study.
- Add mustard powder to cooked broccoli. About 1 g of powdered brown mustard raised uptake more than fourfold.
- Chew well. Thorough chewing of fresh sprouts released more sulforaphane than swallowing them whole.
- Buy sprouts carefully. Keep them cold, use them fresh and follow the FDA's advice if you're in a higher-risk group.
Where does sulforaphane fit in a healthy aging routine?
Sulforaphane is a good reason to keep cruciferous vegetables on the plate and to prepare them in a way that keeps the enzyme working. It isn't a replacement for the habits with the strongest human evidence. Our guides to exercise and longevity, nutrition for healthy aging and sleep and aging cover those, and our longevity supplements buyer's guide shows how to judge the evidence for any compound.
Frequently Asked Questions
What food is highest in sulforaphane?
Broccoli sprouts. Young sprouts of some broccoli varieties had 10 to 100 times more glucoraphanin, the precursor to sulforaphane, than mature broccoli in a 1997 study.
How quickly does sulforaphane get into the blood?
From raw broccoli, blood levels peaked about 1.6 hours after eating in a 2008 study, compared with about 6 hours from cooked broccoli. The body cleared it with a half-life of roughly 2.5 hours.
Is it safe to take sulforaphane every day?
Eating broccoli and other crucifers daily is ordinary food. For concentrated supplements, the published safety data are short-term and small, so ask your doctor or pharmacist before daily use, especially if you take medication.
Is sulforaphane hard on the liver?
In the 2006 safety study, liver enzyme tests stayed normal over 7 days of broccoli sprout extracts. That study was small, so it can't rule out rare effects with long-term use.
Who should avoid raw broccoli sprouts?
The FDA says children, older adults, pregnant women and people with weakened immune systems are especially vulnerable to bacteria that raw sprouts can carry. Cooked broccoli with mustard powder is a safer option for them.
Are broccoli sprouts better than broccoli?
Ounce for ounce, sprouts carry far more glucoraphanin. Mature broccoli still provides sulforaphane plus fiber and other nutrients, especially when eaten raw or with mustard powder.
Sources
- Fahey JW, Zhang Y, Talalay P. Broccoli sprouts: an exceptionally rich source of inducers of enzymes that protect against chemical carcinogens. Proc Natl Acad Sci U S A. 1997;94(19):10367-10372. PubMed 9294217
- Vermeulen M, Klöpping-Ketelaars IW, van den Berg R, Vaes WH. Bioavailability and kinetics of sulforaphane in humans after consumption of cooked versus raw broccoli. J Agric Food Chem. 2008;56(22):10505-10509. PubMed 18950181
- Okunade O, Niranjan K, Ghawi SK, Kuhnle G, Methven L. Supplementation of the diet by exogenous myrosinase via mustard seeds to increase the bioavailability of sulforaphane in healthy human subjects after the consumption of cooked broccoli. Mol Nutr Food Res. 2018;62(18):e1700980. PubMed 29806738
- Shapiro TA, Fahey JW, Wade KL, Stephenson KK, Talalay P. Chemoprotective glucosinolates and isothiocyanates of broccoli sprouts: metabolism and excretion in humans. Cancer Epidemiol Biomarkers Prev. 2001;10(5):501-508. PubMed 11352861
- Sykiotis GP, Bohmann D. Keap1/Nrf2 signaling regulates oxidative stress tolerance and lifespan in Drosophila. Dev Cell. 2008;14(1):76-85. PubMed 18194654
- Zhang X, Shu XO, Xiang YB, et al. Cruciferous vegetable consumption is associated with a reduced risk of total and cardiovascular disease mortality. Am J Clin Nutr. 2011;94(1):240-246. PubMed 21593509
- Egner PA, Chen JG, Zarth AT, 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;7(8):813-823. PubMed 24913818
- Shapiro TA, Fahey JW, Dinkova-Kostova AT, et al. Safety, tolerance, and metabolism of broccoli sprout glucosinolates and isothiocyanates: a clinical phase I study. Nutr Cancer. 2006;55(1):53-62. PubMed 16965241
- Fahey JW, Holtzclaw WD, Wehage SL, Wade KL, Stephenson KK, Talalay P. Sulforaphane bioavailability from glucoraphanin-rich broccoli: control by active endogenous myrosinase. PLoS One. 2015;10(11):e0140963. PubMed 26524341
- Mattson MP. Hormesis defined. Ageing Res Rev. 2008;7(1):1-7. PubMed 18162444
- U.S. Food and Drug Administration. Selecting and Serving Produce Safely. fda.gov
- Images: Jessica Lewis (featured image), Christina & Peter and Eva Bronzini, via Pexels (free Pexels license).
Disclosure: OPA Nutrition sells supplements, including products mentioned in this article. This content is for education only and is not medical advice. Statements about dietary supplements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease. Talk to your healthcare provider before using any supplement, especially if you take medication or have a medical condition.
