Glucosinolates

PhytochemicalGlucosinolateBest with a meal

What is it

Glucosinolates are sulfur-containing plant compounds found in cruciferous vegetables like broccoli, kale, and watercress. They are precursors to bioactive isothiocyanates including sulforaphane.

Evidence for 2 uses

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

Antioxidant and detoxification enzyme activation

Good Evidence

Human studies show broccoli sprout extracts upregulate Nrf2-driven gene expression and influence detoxification of select pollutants.

Cardiometabolic markers

Limited Evidence

Smaller trials report modest improvements in blood pressure or lipid markers; evidence remains preliminary.

How it works

When cruciferous plant tissue is damaged (chopping, chewing, gut bacterial action), the enzyme myrosinase converts glucosinolates into isothiocyanates. Sulforaphane and related compounds activate the Nrf2 transcription factor, which upregulates antioxidant and phase II detoxification enzymes. Effects on inflammation markers, gene expression in the gut, and biotransformation pathways have been documented in human studies.

Dosage

No RDA. Clinical studies of broccoli sprout extracts standardize to 30-200 mg glucoraphanin/day; some products include active myrosinase to enhance conversion.

When and how to take it

Often taken with meals. Pairing with mustard seed (a myrosinase source) can enhance sulforaphane formation from supplements that contain only glucoraphanin.

2 commercial forms

Compare the main delivery options and what they’re best suited for.

Glucoraphanin extract

Most common standardized form.

Variable conversion to sulforaphane depends on gut microbiota or co-supplied myrosinase.

Glucoraphanin + myrosinase

Used in newer products.

Improves sulforaphane yield versus glucoraphanin alone.

Safety

Well tolerated at supplement doses. Very high cruciferous intake combined with iodine deficiency can affect thyroid function. Mild GI symptoms occasional.

Who should be cautious

Caution if iodine-deficient or untreated thyroid disease at very high intakes. Pregnancy and breastfeeding data on concentrated extracts limited.

Interactions

Theoretical induction of phase II enzymes may affect some drug metabolism, though clinical impact at supplement doses is not well defined.

Food sources

Broccoli sprouts (3-day)

Amount
high glucoraphanin per gram
%DV
—

Mature broccoli, kale, cabbage, watercress

Amount
moderate
%DV
—

Frequently asked questions

What is the difference between glucoraphanin and sulforaphane?⌄

Glucoraphanin is the inactive precursor; sulforaphane is the active isothiocyanate produced when glucoraphanin reacts with the enzyme myrosinase.

Does cooking destroy glucosinolates?⌄

Heavy boiling reduces glucosinolate content. Steaming briefly preserves more, and adding raw cruciferous food (like mustard seeds) helps activate isothiocyanate formation.

References

Glucosinolates on Wikidata — Wikidata link

Glucosinolates (ChEBI:24279) — ChEBI link

Glucosinolates on NIH DSLD (US supplement label database) — NIH Dietary Supplement Label Database link

Research on Glucosinolates (PubMed search) — PubMed link

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Evidence-based·How we grade evidence

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.