Benefits
Detox support: higher excretion of some air pollutants
In a 12-week randomized trial in 291 adults in a heavily polluted area of China, a broccoli sprout drink (600 micromoles glucoraphanin plus 40 micromoles sulforaphane a day) raised urinary excretion of benzene breakdown products by 61% and acrolein by 23% versus placebo, but not crotonaldehyde. These are biomarkers; health outcomes were not measured.
NRF2 and glutathione-linked protective enzymes
Sulforaphane activates NRF2, a transcription factor that switches on a set of the cell's own protective genes, including glutathione S-transferases. In a 12-week trial, a broccoli sprout drink increased excretion of glutathione-linked pollutant breakdown products, a sign these enzymes were active in people. The trials did not measure antioxidant outcomes directly.
Blood glucose and metabolic biomarkers
In adults with type 2 diabetes, concentrated broccoli sprout extract for 12 weeks lowered fasting blood glucose and HbA1c in obese participants with poorly controlled blood sugar. In 74 adults with prediabetes, the extract missed its main target, lowering fasting glucose by 0.2 mmol/L overall, with larger drops in an exploratory subgroup linked to gut bacteria.
Social responsiveness and behavior ratings
In an 18-week placebo-controlled trial in 44 young men aged 13 to 27 with autism, daily sulforaphane from broccoli sprout extract improved caregiver and physician behavior ratings, and scores drifted back toward baseline after stopping. It is a single small trial, and sulforaphane is not a treatment for autism; any use should be discussed with a doctor.
Choose products with active myrosinase
Glucoraphanin only turns into sulforaphane when myrosinase is active in the product or when suitable gut bacteria do the conversion. A review found that many broccoli sprout supplements are myrosinase-inactive and that labels do not show this, so look for products that state active myrosinase or that supply sulforaphane itself.
Mechanism of action
NRF2 pathway activation
Sulforaphane is an inducer of NRF2, the transcription factor that activates a battery of cytoprotective genes in cells.
Phase II detoxification enzyme induction
Sulforaphane induces glutathione S-transferases and other protective enzymes that attach glutathione to reactive compounds, which are then excreted in urine as mercapturic acids. A human trial measured higher excretion of these conjugates for benzene and acrolein.
Liver glucose production
In liver cells and diabetic animals, sulforaphane reduced glucose production by moving NRF2 into the cell nucleus and lowering key gluconeogenesis enzymes.
Clinical trials
Randomized double-blind placebo-controlled trial of daily oral sulforaphane (50 to 150 micromoles) from broccoli sprout extract for 18 weeks, then 4 weeks off. Measures: Aberrant Behavior Checklist (ABC), Social Responsiveness Scale (SRS) and Clinical Global Impression (CGI-I). (Singh et al. 2014, Proc Natl Acad Sci U S A)
44 young men aged 13 to 27 with moderate to severe autism (29 sulforaphane, 15 placebo).
ABC scores improved by 34% (P < 0.001) and SRS scores by 17% (P = 0.017) with sulforaphane, versus under 3.3% change with placebo, and more participants improved on CGI-I. Scores rose toward baseline after stopping. Single small trial; some authors filed patent applications.
Randomized placebo-controlled trial of concentrated broccoli sprout extract once daily for 12 weeks in adults treated with metformin or diet (registered as NCT02801448; 103 enrolled; primary outcome change in HbA1c). (Axelsson et al. 2017, Sci Transl Med)
Adults aged 35 to 75 with type 2 diabetes and a BMI of 25 to 40.
Broccoli sprout extract reduced fasting blood glucose and HbA1c in obese participants with poorly controlled diabetes. In the same paper, reduced liver glucose production was shown in liver cells and diabetic animals.
12-week randomized placebo-controlled trial of a broccoli sprout beverage providing 600 micromoles glucoraphanin and 40 micromoles sulforaphane daily; outcome urinary mercapturic acids of benzene, acrolein and crotonaldehyde. (Egner et al. 2014, Cancer Prev Res (Phila))
291 adults from a rural township in Qidong, China, with substantial exposure to airborne pollutants.
Excretion of the glutathione-derived conjugates of benzene rose 61% and acrolein 23% versus placebo (P 0.01 or less), but crotonaldehyde did not change. Sulforaphane bioavailability held steady over 12 weeks. A biomarker outcome; disease was not measured.
Randomized double-blind placebo-controlled trial of broccoli sprout extract once daily for 12 weeks in drug-naive adults; primary outcome a 0.3 mmol/L fall in fasting glucose versus placebo. (Dwibedi et al. 2025, Nat Microbiol)
74 adults with prediabetes (35 extract, 39 placebo).
Missed the primary outcome: fasting glucose fell 0.2 mmol/L versus placebo overall (P = 0.04). An exploratory responder subgroup (mild obesity, low insulin resistance, reduced insulin secretion) fell 0.4 mmol/L and had gut bacteria able to convert glucoraphanin. Digestive side effects occurred; no severe adverse events.