Sulforaphane

non-nutrient/non-botanical

What is it

Sulforaphane is an isothiocyanate compound produced when cruciferous vegetables (especially broccoli and broccoli sprouts) are chopped, chewed, or otherwise processed, activating the enzyme myrosinase to convert its precursor glucoraphanin to sulforaphane. Broccoli sprouts contain the highest concentrations.

How it works

Sulforaphane is one of the most potent natural activators of the Nrf2 transcription factor, a master regulator of cellular antioxidant and detoxification responses. Nrf2 activation upregulates phase II detoxification enzymes including glutathione S-transferases, NAD(P)H quinone dehydrogenase 1, and heme oxygenase-1, enhancing the body's capacity to neutralize reactive oxygen species and carcinogens. Research suggests sulforaphane also modulates inflammation by inhibiting NF-kB activation and reducing pro-inflammatory cytokine production. It influences epigenetic regulation by inhibiting histone deacetylases (HDACs), which has prompted investigation in cancer prevention research. Bioavailability depends critically on intact myrosinase enzyme being available. Cooking destroys myrosinase, but gut bacteria can partially convert glucoraphanin to sulforaphane. Bioavailability is highest from fresh broccoli sprouts (which are richer in both substrate and enzyme) and from supplements containing glucoraphanin combined with active myrosinase.

Evidence for 5 uses

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Antioxidant and detoxification capacity

Grade B

Good evidence

Multiple human trials reliably show sulforaphane increases urinary excretion of detoxified xenobiotic metabolites and increases phase II enzyme activity, suggesting enhanced cellular detoxification capacity.

Air pollution and benzene detoxification

Grade B

Good evidence

A landmark Chinese trial showed broccoli sprout beverage significantly increased excretion of benzene and acrolein metabolites in adults exposed to air pollution.

Helicobacter pylori infection

Grade C

Moderate evidence

Some studies suggest sulforaphane has activity against H. pylori and may reduce gastric inflammation, though not a replacement for antibiotic treatment.

Autism spectrum disorder

Grade C

Moderate evidence

A small randomized trial found sulforaphane improved behavioral symptoms in young men with autism. Further trials have shown mixed results.

Cancer prevention

Grade D

Mixed evidence

Strong preclinical evidence and observational data linking cruciferous vegetable consumption to reduced cancer risk; randomized trials of sulforaphane supplementation for cancer prevention are limited.

4 commercial forms

Broccoli sprout extract with active myrosinase

Highest sulforaphane yield; the enzyme is essential for converting glucoraphanin.

Preferred supplement form. Look for products specifying active myrosinase or 'stabilized sulforaphane'.

Glucoraphanin-only extract

Lower sulforaphane yield; depends on gut bacteria for conversion.

Less effective than products with myrosinase. Conversion is variable between individuals.

Stabilized sulforaphane

Direct sulforaphane is unstable; specialized formulations preserve it.

Bypasses the conversion step but stability and shelf-life are challenges. Available in some premium products.

Fresh broccoli sprouts

Highest natural source of sulforaphane precursors and myrosinase together.

3-day-old sprouts contain 20-50 times more glucoraphanin than mature broccoli.

Dosage

There is no established RDA. Studies have used 30-300 micromoles of sulforaphane equivalent per day, often delivered as broccoli sprout extracts containing 5-30 mg of sulforaphane or its precursor glucoraphanin. Daily consumption of fresh broccoli sprouts (1-2 oz) provides similar amounts.

When and how to take it

Sulforaphane can be taken at any time, with or without food. For supplement forms, products combining glucoraphanin with active myrosinase produce higher sulforaphane yields than glucoraphanin alone. Eating broccoli sprouts requires chewing thoroughly to release the active compound. Consumption of fresh broccoli sprouts on an empty stomach may optimize bioavailability.

Food sources

Food	Amount	%DV
Broccoli sprouts (1 oz)	Highest dietary source; significant sulforaphane equivalent	—
Mature broccoli (1 cup cooked)	Lower sulforaphane; cooking destroys myrosinase	—
Brussels sprouts (1 cup)	Moderate glucoraphanin content	—
Kale (1 cup cooked)	Lower content than broccoli	—
Cabbage, raw (1 cup)	Modest content; raw form preserves enzymes	—

Safety

Sulforaphane and broccoli sprout extracts are generally well tolerated. The most common side effects are mild gastrointestinal symptoms including gas, bloating, and nausea. Some people experience garlic-like body odor from sulfur-containing metabolites. Long-term safety data at high supplemental doses are limited.

Who should be cautious

Safety in pregnancy and breastfeeding at supplemental doses is not well established; culinary intake is considered safe. People with hypothyroidism should not over-consume raw cruciferous vegetables (which contain goitrogens), though sulforaphane supplements at typical doses appear less problematic. People taking medications metabolized by phase I or II enzymes should consult a clinician.

Interactions

Sulforaphane induces phase II detoxification enzymes and may modestly affect the metabolism of medications cleared by these pathways. It may inhibit certain CYP450 enzymes, potentially affecting drug levels. Antiplatelet effects are weak. Most interactions are theoretical rather than well-documented clinically.

Frequently asked questions

How are broccoli sprouts different from regular broccoli?⌄

Broccoli sprouts (3-day old germinated seeds) contain 20-50 times more sulforaphane precursors than mature broccoli, making them the most concentrated dietary source.

Why is myrosinase important?⌄

Myrosinase is the enzyme that converts glucoraphanin into active sulforaphane. Without active myrosinase (destroyed by cooking), sulforaphane yield from supplements or cooked broccoli is much lower.

Does cooking destroy sulforaphane?⌄

Cooking destroys the myrosinase enzyme needed to form sulforaphane from its precursor. Light steaming (3-4 minutes) preserves more enzyme than longer or higher-heat cooking.

How much sulforaphane should I take?⌄

Studies use widely varying doses. A common range is 10-30 mg of sulforaphane equivalent daily from supplements, or several ounces of fresh broccoli sprouts.

Can sulforaphane prevent cancer?⌄

Observational studies link cruciferous vegetable consumption to reduced cancer risk, and preclinical research is strongly supportive. Rigorous human trials of supplementation for cancer prevention are limited.

References

PubChem: Sulforaphane — PubChem link
Wikidata: Sulforaphane — Wikidata link

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Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you're pregnant, breastfeeding, on medications, or managing a chronic condition.