Benefits
Higher sulforaphane yield from cooked broccoli with added mustard powder
In a randomized crossover study in 12 healthy adults, 200 g of cooked broccoli eaten alone gave 9.8 micromoles of a urinary sulforaphane metabolite per gram of creatinine over 24 hours. With 1 g of powdered brown mustard added, it gave 44.7, more than four times as much. Cooking inactivates the broccoli's own myrosinase; the mustard supplied active enzyme.
Greater conversion of glucoraphanin from a broccoli seed extract
In a double-blind crossover study in 16 healthy adults, a single dose of 115 micromoles (50 mg) glucoraphanin from a broccoli seed extract converted 18.6% of the dose to urinary sulforaphane metabolites over 24 hours on its own and 39.8% with 145 mg mustard seed powder. Most of the gain came in the first 8 hours. The extract maker was among the funders and supplied the products.
Active plant enzyme in sprouts and seeds versus enzyme-free extracts
When glucoraphanin came with active myrosinase, as broccoli seed powder or freeze-dried sprouts, about 33 to 42% of the dose was recovered as sulforaphane metabolites in small volunteer studies, versus about 9 to 10% for enzyme-free extracts. In 12 men, fresh broccoli gave about three times the yield of steamed broccoli (32% vs 10%).
Pre-converted sprout drinks made with daikon sprout enzyme
In a crossover trial in 50 adults in China, a broccoli sprout drink pretreated with daikon sprout myrosinase was about 70% bioavailable as sulforaphane, versus about 5% for a glucoraphanin drink that relied on gut bacteria. A trial of the same design found both drinks raised urinary excretion of some air pollutants to a similar degree.
More predictable conversion than relying on gut bacteria
Without active myrosinase, gut bacteria do the conversion, and in Chinese and US volunteers this ranged from about 1% to more than 40% of a glucoraphanin dose; earlier work found that antibiotics with bowel cleansing abolished it. Extracts already converted to sulforaphane were recovered at a steadier 70 to 90%, and the daikon-treated drink varied less between people.
Mechanism of action
Converts glucoraphanin into sulforaphane
Myrosinase hydrolyzes glucoraphanin to release sulforaphane. Added enzyme lets this happen soon after a dose, rather than later through gut bacteria. In a 16-person study, most of the extra sulforaphane from added mustard seed appeared in urine within the first 8 hours.
Heat sensitivity and why mustard seed is used
In lab tests, boiling broccoli inactivated its myrosinase and formed no significant sulforaphane, while powdered mustard seed added after heating restored formation. Mustard species differ: after 10 minutes at 70°C, black mustard enzyme kept 59% of its activity, brown 35% and yellow none, so the powder is added after cooking, not cooked.
A small amount of remaining activity goes a long way
In 15 people, broccoli that had lost 80% of its myrosinase activity gave the same urinary sulforaphane yield as fully active broccoli; with 2% left, or none, the yield was lower. So a fairly small amount of active enzyme may be enough for conversion.
Stomach acid, coating and vitamin C
In a lab digestion model, mustard seed myrosinase worked in the small-intestine phase but not in the acidic stomach phase, and ascorbic acid, an enzyme cofactor, raised conversion. In a pilot study in people, acid-lowering omeprazole raised conversion from 25.7% to 33.6% with uncoated tablets, while enteric-coated tablets reached about 36% either way.
Clinical trials
Randomized crossover study comparing cooked broccoli eaten alone or with powdered brown mustard as a source of active myrosinase; outcome sulforaphane N-acetylcysteine in 24-hour urine. (Okunade et al. 2018, Mol Nutr Food Res)
12 healthy adults.
200 g of cooked broccoli alone gave 9.8 micromoles of the sulforaphane metabolite per gram of creatinine; with 1 g of powdered brown mustard it gave 44.7, more than four times as much. A single-meal bioavailability study; no health outcome was measured.
Randomized, double-blind crossover study of a single capsule dose of broccoli seed extract (115 micromoles, 50 mg glucoraphanin) with or without 145 mg mustard seed powder, 14-day washout; primary outcome conversion to urinary sulforaphane metabolites over 24 hours. Funded in part by the extract maker, which also supplied the extract and mustard seed powder. (Mastaloudis et al. 2026, Sci Rep)
16 healthy adults (9 women, 7 men), mean age about 40.
Conversion rose from 18.6% of the dose without mustard seed to 39.8% with it (p = 0.0016), mostly in the first 8 hours (25.4% vs 8.0%); for 8 to 24 hours the paper reports 11.7% vs 8.9%. No adverse events. One author was employed by the extract maker and one consulted for it.
Crossover trial with a 5-day run-in, 7 days on each drink and a 5-day washout: a glucoraphanin-rich drink (800 micromoles) versus a sulforaphane-rich drink (150 micromoles) made by treating the same extract with daikon sprout myrosinase. (Egner et al. 2011, Cancer Prev Res (Phila))
50 adults in Qidong, China, randomized (48 completed).
Mean bioavailability was about 70% for the myrosinase-treated drink and about 5% for the glucoraphanin drink, with less variation between people on the treated drink. The glucoraphanin drink was eliminated more slowly. A companion analysis found both drinks raised pollutant excretion similarly.
Series of small dosing studies comparing glucoraphanin given with active plant myrosinase (broccoli seed powder, freeze-dried sprouts) or without it (boiled sprout extract, a commercial seed extract), with 24-hour urine collection. (Fahey et al. 2015, PLoS One)
Sub-studies of 4 to 20 healthy volunteers each, with a core group of 5 taking part in most of them.
With active myrosinase, about 33 to 42% of the glucoraphanin dose was recovered as sulforaphane metabolites, versus about 9 to 10% without it, a 3- to 4-fold difference. The commercial extract matched the boiled extract. Very small numbers.
Crossover study of 200 g fresh or steamed broccoli after a 48-hour diet free of glucosinolates, with blood and urine collected for 24 hours. (Conaway et al. 2000, Nutr Cancer)
12 men.
Urinary isothiocyanate excretion was 32.3% of the ingested amount after fresh broccoli and 10.2% after steamed broccoli, about three times more, attributed to heat inactivation of myrosinase. Excretion occurred mainly 2 to 12 hours after eating.
Randomized study of five broccoli products with similar glucoraphanin content but different remaining myrosinase activity, measuring urinary sulforaphane and iberin conjugates. (Oliviero et al. 2014, Mol Nutr Food Res)
15 participants.
Broccoli that had lost 80% of its enzyme activity gave the same urinary yield as fully active broccoli. With 2% activity left, 17% of the glucoraphanin was recovered as sulforaphane conjugates; fully inactivated broccoli gave the lowest yield, 10%.
Four test meals a week apart (sprouts, powder, both, or neither) in cereal and yogurt; sprouts supplied myrosinase and the powder had none. (Cramer et al. 2012, Br J Nutr)
4 healthy men.
24-hour urinary recovery of sulforaphane was 24% from the powder alone, 60% from sprouts and 65% from the combination, and sulforaphane from the powder appeared earlier when eaten with sprouts. Very small study.