Broccoli
EVIDENCE: MIXEDAlso sold as: Brassica oleracea, broccoli sprout, sulforaphane, glucoraphanin
Broccoli contains compounds that can produce sulforaphane, which activates cellular antioxidant and detoxification pathways. Human evidence for health outcomes is still developing. A supplement’s preparation determines whether it supplies sulforaphane or the materials needed to form it.
Compiled by iSupplementReviews editorial team ·Updated 2026-10-13 · 5 sources
- Type
- Cruciferous vegetable extract
- Studied dose
- ~10–100 mg sulforaphane-equivalent (sprout extracts)
- Best form
- broccoli *sprout* extract with glucoraphanin + active myrosinase — mature-veg powder delivers a fraction of the potential
- Our rating
- MIXED — Some human evidence, inconsistent or indirect
What is broccoli extract?
Broccoli extracts may supply glucoraphanin, which can be converted to sulforaphane. Sulforaphane activates the Nrf2 cellular-defense pathway. Young sprouts can contain about 100 times more glucoraphanin than mature heads, and heat can damage the myrosinase enzyme needed for conversion.
The forms that matter
| Form | What it is | Notes |
|---|---|---|
| Sprout extract + myrosinase | Precursor + the activating enzyme | The studied material — highest yield |
| Stabilized sulforaphane | Pre-formed active | Works, shelf-life challenges |
| Glucoraphanin alone | Precursor without enzyme | Relies on gut bacteria — ~10% conversion |
| Mature-veg powder | Ground broccoli | Minimal glucoraphanin — label dressing |
Where does it come from?
Cultivated brassica, the same species family as cabbage, kale, and mustard. Sprout extracts are grown specifically for supplement material because the young plant concentrates glucoraphanin.
How does it work in the body?
Glucoraphanin gets converted (by the myrosinase enzyme or gut bacteria) into sulforaphane, which activates Nrf2, the switch that turns on Phase-2 detox enzymes and the body’s own antioxidant systems (glutathione, NADPH enzymes). It’s hormetic: a mild chemical stressor that makes cells upregulate their own defenses. An elegant mechanism with decades of basic-science support.
What is broccoli extract claimed to do?
Detoxification and antioxidant support, cancer prevention (the epidemiology-driven claim), H. pylori suppression, blood-sugar support, and neuroprotection.
What does the research show?
| Claim | Evidence | Dose studied | Verdict |
|---|---|---|---|
| Detox-enzyme/pollutant excretion | Human RCT (Egner 2014) | sprout beverage, 12 wk | Supported — biomarker level |
| H. pylori suppression | Small trials (Yanaka 2009) | 70 g sprouts/day, 8 wk | Early positive |
| Cancer prevention | Population studies + lab work | dietary | Unproven in trials |
| Glycemic effects | Small diabetic trials | high-dose extract | Early |
| Autism symptoms | One small controversial RCT (Singh 2014) | sulforaphane | Preliminary |
| Neuroprotection | Animal/preclinical | — | Insufficient |
The pollution-detox landmark
Egner et al. (2014, Cancer Prev Res): ~290 residents of Qidong, China, a region with heavy air pollution, drank a broccoli-sprout beverage for 12 weeks. Benzene-metabolite excretion rose ~61% and stayed elevated. The cleanest proof that the detox mechanism works in humans, not just in theory.
H. pylori and the prostate-adjacent signals
Small dietary studies found changes in H. pylori activity and prostate-related gene expression. These are early findings, not evidence of infection eradication or a prostate treatment.
Yanaka 2009: daily sprouts reduced H. pylori activity markers; suppression, not eradication. Separately, a small dietary trial in prostate-cancer patients (Traka 2013) showed broccoli-rich diets altered relevant gene expression. Interesting, biomarker-level, early.
Cancer prevention — the grade
Cruciferous intake is associated with lower rates of several cancers in population studies; sulforaphane kills cancer cells in dishes and slows tumors in animals. No human prevention trial has been completed. The mechanism is real; the outcome claim is not yet evidence.
What doesn’t broccoli extract do?
It isn’t proven to prevent or treat cancer in humans, and mature-vegetable powders without myrosinase deliver a fraction of the implied sulforaphane.
What dose was studied?
Human trials used sprout extracts delivering ~10–100 mg sulforaphane-equivalent, requiring glucoraphanin + active myrosinase or pre-formed sulforaphane. Whole-veg powder at small doses sits far below functional range.
Side effects
Mild digestive upset at high doses; goitrogenic potential is theoretical at supplement doses (relevant only to iodine-deficient heavy users).
Drug interactions
Few documented. High-dose sulforaphane can induce drug-metabolizing enzymes (that’s the mechanism); worth mentioning to prescribers for narrow-margin drugs.
Who should not take broccoli extract?
Iodine-deficient individuals at very high doses (the goitrogen theory), and anyone using it as a cancer-treatment substitute.
What the authorities say
WCRF/AICR position cruciferous vegetables as “probable” cancer-protective foods: a carefully worded epidemiology endorsement, not a supplement endorsement. The distinction matters. Evidence supports eating the vegetable family; the extract extrapolates from it.
What to know about broccoli extract
Broccoli’s cellular effects are better established than cancer-prevention benefits from supplements. Check for the preparation, glucoraphanin or sulforaphane amount, and myrosinase. Ordinary powder in an unspecified blend may not match a studied extract.
Frequently asked questions about Broccoli
What does sulforaphane do?
It activates Nrf2, the master switch for the body's own antioxidant and detoxification enzymes. Sulforaphane doesn't act as an antioxidant itself so much as it turns on your cells' defense systems, including detox enzymes and glutathione production. It's one of the most potent natural Nrf2 activators known.
Does broccoli extract prevent cancer?
Not proven in humans. Eating cruciferous vegetables is associated with lower rates of several cancers in population studies, and sulforaphane shows anti-cancer effects in cell and animal work, but no human trial has demonstrated prevention. Human data so far is biomarker-level (detox-enzyme activation, pollutant excretion; Egner 2014).
Is broccoli sprout better than mature broccoli powder?
Yes for sulforaphane potential. Sprouts carry up to ~100× the glucoraphanin (the precursor) of mature broccoli. And the product needs active myrosinase (the converting enzyme); processing destroys it, which is why serious formulas either include it or supply pre-formed sulforaphane.
Can broccoli supplements affect your thyroid?
Crucifers contain goitrogenic compounds that could theoretically interfere with iodine uptake; relevant only at very high intakes or with iodine deficiency. Normal supplement doses of sprout extract aren't a practical thyroid concern.
Did broccoli extract really help people detox pollution?
Yes. The landmark human trial (Egner et al., 2014) gave residents of a heavily polluted region in China a broccoli-sprout beverage for 12 weeks and saw rapid, sustained increases in excretion of benzene and other airborne carcinogen metabolites. It's the clearest demonstration that the mechanism works in humans.
References
- [1]Egner PA et al. — Broccoli sprout beverage enhances detoxication of airborne pollutants, RCT (Cancer Prev Res, 2014)
- [2]Fahey JW et al. — Sulforaphane bioavailability depends on myrosinase (Mol Nutr Food Res)
- [3]Yanaka A et al. — Broccoli sprouts suppress H. pylori activity (small trial, 2009)
- [4]Singh K et al. — Sulforaphane in autism spectrum disorder (PNAS, 2014 — small, controversial)
- [5]World Cancer Research Fund — Cruciferous vegetables and cancer evidence review
Products we reviewed containing Broccoli
Based on recorded labels or seller-described formulas. Inclusion does not establish a match to the strains, preparations or amounts studied here; check each review's disclosure limits.