Evidence-based·Last reviewed May 31, 2026·How we grade evidence

Broccoli

BotanicalBest with a meal

Broccoli — and especially broccoli sprouts — is the headline dietary source of sulforaphane, a potent activator of the Nrf2 detoxification pathway. Real RCT evidence supports biomarker effects: increased excretion of air-pollutant carcinogens (Egner 2014 Qidong), reduced H. pylori burden (Yanaka 2009), and a single intriguing autism trial (Singh 2014). Sulforaphane is the workhorse; broccoli is the carrier. Cooking broccoli destroys the enzyme (myrosinase) that produces sulforaphane — eat some raw or use a sprout product with active myrosinase.

Quick decision guide

May help most

Adults wanting a food-first source of sulforaphane and the broader cruciferous-vegetable health package (fiber, vitamin C, vitamin K, folate). Broccoli sprouts are the most concentrated practical food source.

Common dosing range

Mature broccoli: 1–2 cups/day as part of a varied diet. Broccoli sprouts: 30–100 g/day delivers ~100–400 µmol sulforaphane equivalents. Supplement extracts: 100–200 mg standardised to ≥10% glucoraphanin, ideally WITH added myrosinase or co-consumed with mustard powder.

When to expect effects

Biomarker effects (urinary metabolites): hours. H. pylori burden / autism behavioural endpoints in trials: weeks.

Watch out for

Cooking destroys myrosinase. Boiled broccoli supplies far less sulforaphane than raw, lightly-steamed, or sprouted broccoli — unless you add myrosinase from another source (raw broccoli, mustard powder).

Evidence snapshot

Phase II / Nrf2 detoxification (biomarker)Moderate
H. pylori burden reductionEmerging
Autism (sprout extract trial)Emerging
Hard cancer endpoint preventionLow
Cardiovascular biomarkersLow

What is it

Broccoli (Brassica oleracea var. italica) is a cruciferous vegetable famous for its glucosinolate content, particularly glucoraphanin, which converts to sulforaphane — a compound extensively studied for detoxification enzyme induction, antioxidant effects, and possible cancer prevention.

Is it worth it for you?

Use this as a quick fit check, not a diagnosis.

Worth considering if…

You want a whole-food cruciferous vegetable habit and value the fiber, vitamin C, K, and folate alongside sulforaphane
You're in a high-pollution environment and want a food approach to support detoxification pathways (Egner 2014 evidence)
You have H. pylori and want a low-risk adjunct (not replacement) to standard triple therapy
You're considering broccoli sprouts as a more concentrated source of sulforaphane than mature broccoli
You're trialling a broccoli sprout EXTRACT — verify it includes active myrosinase or a co-consumption strategy

Probably skip if…

You're hoping a sulforaphane supplement will prevent cancer with anything close to drug-like reliability — hard endpoint trials don't exist
You're taking hypothyroid medication and have a personal history of thyroid problems with cruciferous overload (rare; mostly an issue with extreme intakes)
You're on warfarin and your INR isn't stable — large variable vitamin K intake from sudden broccoli ramp-up can shift INR
You only eat heavily boiled broccoli and expect sulforaphane benefits — without myrosinase you get little SFN
You're spending heavily on broccoli sprout extract that lacks myrosinase or a co-formulation

Evidence at a glance

Phase II / Nrf2 detoxification and air-pollutant excretion

Good Evidence
Effect
61% increase in urinary benzene-mercapturic-acid excretion; 23% increase in acrolein metabolite excretion at 600 µmol glucoraphanin + 40 µmol SFN/day for 12 weeks
Best fit
Adults in high-pollution environments; smokers; occupationally exposed adults
Time
Days to weeks for urinary marker change

Helicobacter pylori burden (adjunct)

Limited Evidence
Effect
Reduced urea breath test values and stool antigen vs control; no eradication
Best fit
H. pylori-positive adults who want a dietary adjunct alongside or after standard antibiotic therapy
Time
8 weeks in trial; effects revert after stopping

Autism spectrum disorder (sulforaphane)

Limited Evidence
Effect
~34% reduction in Aberrant Behavior Checklist scores in the treatment arm; reversible on stopping
Best fit
Young men with moderate-to-severe ASD whose families want to trial a low-risk adjunct alongside standard support
Time
18 weeks in the Singh trial

Cancer prevention (mechanistic / observational)

Mixed Evidence
Effect
Observational reduction in several cancer types; mechanism supportive; no RCT confirmation
Best fit
Anyone eating a varied diet who can swap some calories for cruciferous vegetables
Time
Decades for cancer-incidence effects

Airway inflammation (asthma, COPD)

Mixed Evidence
Effect
No consistent clinical benefit in published RCTs of moderate asthma
Best fit
None established
Time
Not established for clinical airway endpoints

Evidence for 5 uses

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

Phase II / Nrf2 detoxification and air-pollutant excretion

Biomarker support
Good Evidence

Egner 2014 randomized 291 adults in Qidong, China to a broccoli sprout beverage delivering 600 µmol glucoraphanin and 40 µmol sulforaphane/day or placebo for 12 weeks. Urinary excretion of benzene metabolites rose 61% and acrolein metabolites 23% — i.e., the sulforaphane group cleared two genotoxic air pollutants faster. This is the cleanest demonstration of the Nrf2-detox mechanism in humans. It's a biomarker study, not a hard-endpoint cancer-prevention trial.

Effect size
61% increase in urinary benzene-mercapturic-acid excretion; 23% increase in acrolein metabolite excretion at 600 µmol glucoraphanin + 40 µmol SFN/day for 12 weeks
Time to effect
Days to weeks for urinary marker change
Best fit
Adults in high-pollution environments; smokers; occupationally exposed adults
Less likely
Healthy adults with low pollutant exposure — the mechanism is real but the practical benefit is uncertain

Bottom line: Real, well-replicated biomarker effect. Translates to clinical disease prevention is still an open question.

SourceEgner et al., 2014 (Qidong) — PubMed — Cancer Prevention Research

Helicobacter pylori burden (adjunct)

Disease adjunct
Limited Evidence

Yanaka 2009 RCT in 48 H. pylori-positive Japanese adults: 70 g broccoli sprouts/day (~420 µmol SFN equivalents) for 8 weeks reduced urea breath test values and stool antigen vs alfalfa-sprout control. Sulforaphane has direct antimicrobial activity against H. pylori in vitro. Sprouts did NOT eradicate the infection — they reduced burden — and values returned to baseline within 8 weeks after stopping. Standard triple/quadruple therapy remains the eradication standard.

Effect size
Reduced urea breath test values and stool antigen vs control; no eradication
Time to effect
8 weeks in trial; effects revert after stopping
Best fit
H. pylori-positive adults who want a dietary adjunct alongside or after standard antibiotic therapy
Less likely
Anyone hoping broccoli sprouts will replace antibiotic eradication — they don't

Bottom line: Worth a try as adjunct or after triple therapy. Don't skip prescribed antibiotics.

SourceYanaka et al., 2009 (H. pylori) — PubMed — Cancer Prevention Research

Autism spectrum disorder (sulforaphane)

Disease adjunct
Limited Evidence

Singh 2014 was an 18-week double-blind RCT in 44 young men with moderate-to-severe ASD: weight-tiered broccoli sprout extract (50–150 µmol SFN/day) vs placebo. Significant improvements on the Aberrant Behavior Checklist (~34% reduction) and Social Responsiveness Scale; effects reversed within weeks of stopping. The trial was small and the population narrow; replication in larger, more diverse cohorts has been mixed. The proposed mechanism is improved heat-shock protein / oxidative stress handling.

Effect size
~34% reduction in Aberrant Behavior Checklist scores in the treatment arm; reversible on stopping
Time to effect
18 weeks in the Singh trial
Best fit
Young men with moderate-to-severe ASD whose families want to trial a low-risk adjunct alongside standard support
Less likely
Anyone expecting sulforaphane to be a 'cure'; replication data are mixed

Bottom line: Promising small RCT; replication is mixed. Discuss with the clinician managing the autism care plan.

SourceSingh et al., 2014 (autism) — PubMed — PNAS

Cancer prevention (mechanistic / observational)

Supplement benefit
Mixed Evidence

Cruciferous vegetable intake is associated with modestly lower risk of several cancers in cohort studies (notably bladder, colorectal, lung, breast — but with heterogeneous estimates and confounding from overall dietary patterns). Mechanistically, sulforaphane activates Nrf2 detoxification, induces phase II enzymes, and modulates HDAC. There are no hard-endpoint cancer-prevention RCTs. Eat cruciferous vegetables as part of a healthy diet, not as a stand-alone cancer-prevention treatment.

Effect size
Observational reduction in several cancer types; mechanism supportive; no RCT confirmation
Time to effect
Decades for cancer-incidence effects
Best fit
Anyone eating a varied diet who can swap some calories for cruciferous vegetables
Less likely
Anyone hoping a supplement can substitute for established cancer screening and lifestyle measures

Bottom line: Eat broccoli; don't believe a supplement label that promises cancer prevention.

SourceEgner et al., 2014 (Qidong) — PubMed — Cancer Prevention Research

Airway inflammation (asthma, COPD)

Supplement benefit
Mixed Evidence

Small mechanistic and preliminary human studies have explored sulforaphane as an Nrf2-driven anti-inflammatory in airway diseases. Results in larger trials (e.g., a published phase 2 asthma trial) have been negative or mixed. The pre-clinical mechanism is genuine, but clinical translation is unproven.

Effect size
No consistent clinical benefit in published RCTs of moderate asthma
Time to effect
Not established for clinical airway endpoints
Best fit
None established
Less likely
Adults with poorly-controlled asthma or COPD seeking primary treatment

Bottom line: Skip as airway-disease treatment. Standard inhalers and pulmonologist guidance are the right path.

SourceEgner et al., 2014 (Qidong) — PubMed — Cancer Prevention Research

How it works

Broccoli's most notable supplement use centers on sulforaphane, generated from glucoraphanin via the enzyme myrosinase. Myrosinase is present in raw broccoli but destroyed by cooking; supplements often provide both glucoraphanin and myrosinase together. Sulforaphane activates the Nrf2 pathway, increasing production of phase II detoxification enzymes (glutathione transferases, NQO1) that neutralize toxins and oxidative stress. Clinical research on sulforaphane/broccoli extracts has examined effects on airway inflammation (asthma, COPD), blood pressure, autism (small trials suggesting behavioral improvements), Helicobacter pylori suppression, and inflammatory markers. Effects are often modest but show consistent biological signal across studies. Whole broccoli provides additional nutrients (vitamin C, K, folate, fiber) and cancer-protective compounds (indole-3-carbinol, DIM) beyond sulforaphane.

How to take it

1. Typical dose
• Mature broccoli: 1–2 cups/day raw or lightly steamed as part of a varied diet • Broccoli sprouts: 30–100 g/day (~100–400 µmol sulforaphane equivalents) • Broccoli sprout EXTRACT supplement: 100–200 mg standardised to ≥10% glucoraphanin — IDEALLY with active myrosinase added • Singh 2014 ASD dose: 50–150 µmol SFN/day weight-tiered • Egner 2014 Qidong dose: 600 µmol glucoraphanin + 40 µmol SFN/day
2. Higher studied dose
Egner used 600 µmol glucoraphanin/day for 12 weeks safely. Singh used up to 150 µmol SFN/day for 18 weeks. Doses much higher than this haven't been systematically studied in adults; very high intakes can cause GI upset and theoretical thyroid concerns.
3. Timing
With meals. If using a sprout extract without myrosinase, take it WITH a fresh source of myrosinase: a teaspoon of mustard powder, fresh wasabi, daikon, arugula, or fresh broccoli sprouts will all dramatically increase sulforaphane yield.
4. With food
With food.
5. Split dosing
Once daily is fine for mature broccoli or sprouts. Split sprout extract doses across 2 servings if going to the upper range of intake.
6. How long to try
Indefinite as part of a varied diet. Trials that demonstrated effects (Egner 12 weeks, Singh 18 weeks, Yanaka 8 weeks) all required ongoing intake — biomarker and clinical effects reversed within weeks of stopping.

What to track

Whether your supplement provides active myrosinase — without it, sulforaphane bioavailability is roughly one-seventh of what an equivalent dose from fresh sprouts delivers (Atwell 2015)
Vitamin K intake stability if you're on warfarin (large sudden broccoli increases shift INR)
GI tolerance (gas, bloating) — common with sudden cruciferous ramp-up

Bottom line: Real food first. If you supplement, choose a product with active myrosinase or co-consume with mustard powder, and stay realistic about what sulforaphane has been shown to do (biomarkers and small clinical trials, not cancer prevention).

5 commercial forms

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

Fresh broccoli sprouts (raw, 3–5 days old)

Highest SFN density

Three-to-five-day-old sprouts deliver ~10–100× more glucoraphanin per gram than mature broccoli, plus active myrosinase. The form used by Yanaka 2009 and most concentrated dietary SFN delivery. Food-safety caveat for raw sprouts in pregnant / immunocompromised people.

Highest practical bioavailability; intrinsic myrosinase converts glucoraphanin in real time.

Fresh mature broccoli (raw or lightly steamed)

Whole food

1–2 cups/day delivers meaningful glucoraphanin plus fiber, vitamin C, K, folate. Light steaming (~3 minutes) preserves most of the myrosinase; boiling longer denatures it. Even with denatured myrosinase, eating raw mustard or other crucifers at the same meal restores SFN production.

Lower SFN density per gram than sprouts; the whole-food matrix is broadly beneficial.

Broccoli sprout extract WITH active myrosinase

Recommended supplement

Standardised extract delivering glucoraphanin plus active myrosinase. The form most consistent with Egner 2014's beverage approach. Pick this over myrosinase-free extracts.

Reasonable approximation of fresh sprout delivery when myrosinase is genuinely active.

Broccoli sprout extract WITHOUT myrosinase

Pair with mustard

Cheaper extracts deliver glucoraphanin alone, hoping gut bacteria will produce SFN. Atwell 2015 showed bioavailability is ~⅐ of sprouts. Co-consume with fresh mustard powder, daikon, or sprouts at the same meal to add myrosinase.

Much lower than myrosinase-active forms unless co-consumed with an exogenous myrosinase source.

Stabilised sulforaphane (preformed)

Niche / expensive

Direct sulforaphane (not glucoraphanin) products skip the myrosinase question but are expensive and SFN is chemically unstable — formulation quality matters a lot. Useful for research; cost-benefit unclear vs sprout extracts with myrosinase.

Direct SFN delivery; stability and formulation are the practical concerns.

Safety

Know the common side effects, key cautions, and who should avoid it.

Common side effects

gas / bloatingloose stools at high sprout intakesmild GI discomfort

Serious risks

  • Thyroid effects from very high cruciferous intake in iodine-deficient adults — goitrogens (thiocyanates from glucosinolates) can interfere with iodine uptake at extreme intakes. Typical Western intakes are not high enough to matter clinically. Maintain adequate iodine intake if you eat large daily quantities of raw cruciferous vegetables.

    SourceUSDA FoodData Central — Broccoli, raw — USDA

  • INR fluctuation in warfarin users — broccoli is vitamin K-rich. Sudden large changes in intake shift INR. Keep vitamin K-containing greens fairly consistent rather than dramatically up- or down-shifting.

    SourceUSDA FoodData Central — Broccoli, raw — USDA

  • Sprout-borne foodborne illness (E. coli, Salmonella, Listeria) — raw sprouts have caused outbreaks. Use sprouts from reputable producers with clean growing standards; consider rinsing thoroughly. People at higher infection risk (pregnant, immunocompromised, elderly, young children) should avoid raw sprouts.

    SourceUSDA FoodData Central — Broccoli, raw — USDA

Who should avoid it

Pregnancy & breastfeeding

Cooked broccoli is a healthy pregnancy food — folate, vitamin K, fiber, vitamin C. Avoid RAW broccoli sprouts during pregnancy due to documented sprout-related Listeria, E. coli, and Salmonella outbreaks. Sulforaphane sprout EXTRACT supplements have not been formally tested in pregnancy and should be discussed with your obstetric provider before use.

SourceUSDA FoodData Central — Broccoli, raw — USDA

Bottom line: Generally very safe as food. Raw sprout food-safety, warfarin INR consistency, and (at extremes) iodine adequacy are the practical cautions.

Interactions

warfarinModerate

Broccoli is vitamin K-rich (~92 µg per cup raw). Sudden large changes in intake shift INR. Keep your weekly broccoli intake fairly consistent rather than dramatically up- or down-shifting.

SourceUSDA FoodData Central — Broccoli, raw — USDA
levothyroxineMinor

No specific clinical interaction at normal cruciferous intake. At extreme daily intakes in iodine-deficient adults, theoretical interference with thyroid function. Mostly not relevant in iodine-replete adults.

SourceUSDA FoodData Central — Broccoli, raw — USDA
acetaminophen / paracetamol metabolism (high cruciferous intake)Minor

Cruciferous vegetables modestly induce CYP1A2 and phase II conjugation pathways; can subtly accelerate clearance of some drugs. Clinical significance generally minor at normal intakes.

CYP1A2-substrate drugs (theophylline, caffeine)Minor

Induction of CYP1A2 at high cruciferous intakes can modestly increase clearance of these substrates.

Documented interactions

Evidence-graded pair pages with sources, dosing notes, and timing guidance — a complement to the narrative section above.

Warnings (1)

+ warfarin

moderate

Broccoli is one of the most vitamin K1 (phylloquinone)-rich common vegetables, and vitamin K is the cofactor warfarin works by blocking. It is not about avoiding broccoli but about consistency: large swings in intake can move your INR and reduce warfarin's effect or raise bleeding risk.

See all 1 Broccoli interaction →

Food sources

Broccoli sprouts (raw, ~3–5 days old)

Amount
30 g (~100–300 µmol SFN equivalents)
%DV
—

Broccoli, raw (chopped)

Amount
1 cup / 91 g (~31 kcal, 81 mg vit C, 92 µg vit K, 2.4 g fiber)
%DV
90%

Broccoli, lightly steamed (3 min)

Amount
1 cup (~55 kcal, similar SFN yield to raw if myrosinase preserved)
%DV
90%

Broccoli, boiled 10+ min

Amount
1 cup (myrosinase denatured; minimal SFN unless mustard/daikon added at meal)
%DV
90%

Brussels sprouts (cooked)

Amount
½ cup (~28 kcal, ~76 mg vit C, glucoraphanin-rich)
%DV
—

Cabbage, raw (shredded)

Amount
1 cup (~22 kcal, ~37 mg vit C, mixed glucosinolates)
%DV
—

Kale (cooked)

Amount
1 cup (~36 kcal, ~53 mg vit C, mixed cruciferous compounds)
%DV
—

Choosing a product

What to look for on the label — and what to be skeptical of.

Look for…

Fresh broccoli or broccoli sprouts from a reputable producer (cooked broccoli for pregnant/immunocompromised; sprouts otherwise)
If buying a sulforaphane SUPPLEMENT: glucoraphanin content stated in mg or µmol per serving AND active myrosinase listed in the ingredient panel
Standardised broccoli sprout extract (BroccoMax, Avmacol, Truebroc-class) with disclosed glucoraphanin and myrosinase content
Third-party tested (USP, NSF, ConsumerLab)
If product doesn't include myrosinase, plan to co-consume with mustard powder, daikon, or fresh broccoli sprouts at the same meal

Be skeptical of…

'Prevents cancer' — no hard-endpoint RCT supports this for broccoli or sulforaphane supplements
'Detoxifies the liver' — vague claim; what's actually shown is upregulated phase II enzymes and faster excretion of specific pollutants in biomarker studies
'10× more sulforaphane' marketing without disclosing whether myrosinase is included — without myrosinase, glucoraphanin numbers are misleading
'Reverses autism' — Singh 2014 showed reversible symptom improvement, not cure; replication mixed
Combination 'detox' products burying broccoli extract in a proprietary blend with unstated glucoraphanin

Frequently asked questions

Are broccoli sprouts more potent than mature broccoli?⌄

Yes — 3-day-old broccoli sprouts contain 20-50x more glucoraphanin than mature broccoli per gram. This is why sprouts are emphasized in sulforaphane research.

Should I take sulforaphane extracts?⌄

Reasonable for people interested in the specific Nrf2/detox effects. For general health, eating cruciferous vegetables regularly may be sufficient.

Does cooking destroy the benefits?⌄

Cooking destroys myrosinase, the enzyme that makes sulforaphane from glucoraphanin. Eating raw broccoli with food, or adding mustard powder to cooked broccoli, restores some activity.

References by claim

Phase II / Nrf2 detoxification and air-pollutant excretion

Egner et al., 2014 (Qidong) — PubMed — Cancer Prevention Research (2014) link

Autism spectrum disorder (sulforaphane)

Singh et al., 2014 (autism) — PubMed — PNAS (2014) link

Helicobacter pylori burden (adjunct)

Yanaka et al., 2009 (H. pylori) — PubMed — Cancer Prevention Research (2009) link

Safety

USDA FoodData Central — Broccoli, raw — USDA (2024) link

Other references

Atwell et al., 2015 — PubMed — Cancer Prevention Research (2015) link

Broccoli on Wikidata — Wikidata link

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Evidence-based·Last reviewed May 31, 2026·Evidence current as of May 31, 2026·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.