Broccoli and cauliflower: the vegetables that talk to your medicines

A meta-analysis of 23 dietary intervention trials found that diets rich in cruciferous vegetables such as broccoli and cauliflower raised the activity of the drug-processing enzyme CYP1A2 by 20 to 40 percent, though not every included trial was randomized and the clinical meaning is unclear. That enzyme handles caffeine, theophylline and clozapine, so the question matters most for large or changing portions. The second interaction is vitamin K. A cup of cooked broccoli and cauliflower, 160 g in US survey data, carries about 81 micrograms of it, a figure recalculated from 100 g. In healthy volunteers kept stably on an anticoagulant, 150 micrograms of vitamin K1 a day was the lowest dose that lowered INR, in a non-randomized study that did not report how many took part. No trial we found tested the two vegetables eaten together, and cauliflower alone has almost no trial data. Most of what follows is about broccoli or cruciferous vegetables as a group.

As people eat it, per 3.5 oz (100 g)

How much is actually in it

• USDA survey data list cooked broccoli and cauliflower with added fat at 46 calories, 34.6 mg vitamin C, 50.5 mcg vitamin K, 47 mcg folate and 2.8 g fiber per 3.5 oz (100 g). — - (n = -) Evidence E source
  Per 100 g: 46 calories, vitamin C 34.6 mg, vitamin K 50.5 mcg, folate 47 mcg, fiber 2.8 g, sodium 135 mg

What a real portion looks like

• Observational data from 89 studies link high cruciferous vegetable intake with 19% lower risk of digestive cancers, about 7% lower for each extra 50 g a day up to 75 g. — 81 articles covering 89 observational studies (n = 89 studies) Evidence C source
  RR 0.81 (0.76-0.87) highest vs lowest intake; RR 0.93 per 50 g/day below 75 g/day
• A cup of cooked broccoli and cauliflower weighs 5.6 oz (160 g) in US survey data and supplies about 55 mg vitamin C, 81 mcg vitamin K and 4.5 g fiber. — - (n = -) Evidence E source
  1 cup 160 g: 74 calories, vitamin C 55.4 mg, vitamin K 80.8 mcg, folate 75.2 mcg, fiber 4.5 g, sodium 216 mg

What your body absorbs

• In stably anticoagulated volunteers, 150 mcg of vitamin K1 a day was the lowest dose that lowered INR. — Healthy volunteers stably anticoagulated on individualized doses for 13 weeks, weekly incremental vitamin K1 doses then vitamin K-rich meals Evidence C source
  INR threshold 150 mcg/day vitamin K1; clinically relevant change in 25% of participants at that dose

What cooking and storage change

• In a crossover trial in 12 adults, adding 1 g of powdered brown mustard to 7.1 oz (200 g) of cooked broccoli raised sulforaphane uptake more than fourfold, because cooking destroys the plant's own myrosinase. — 12 healthy adults, 200 g cooked broccoli with or without 1 g powdered brown mustard, 24 h urine (n = 12) Evidence B source
  Urinary SF-NAC 9.8 +/- 5.1 vs 44.7 +/- 33.9 µmol per g creatinine without vs with mustard

What it does to your health

• Observational data from 12 cohort studies with about 700,000 people link higher broccoli intake with 11% lower cancer risk. — 12 cohort studies, 699,482 individuals, plus 23 case-control studies (n = 699482) Evidence C source
  Cohort RR 0.89 (95% CI 0.82 to 0.96), I2 11%; case-control OR 0.64 (0.58 to 0.70)

Safety, limits and interactions

• A meta-analysis of 23 dietary intervention trials found that diets rich in cruciferous vegetables such as broccoli and cauliflower raise CYP1A2 drug-metabolizing activity by 20% to 40%. — 23 human dietary intervention trials with drug metabolism end points; broccoli, Brussels sprout, cabbage, cauliflower, radish, watercress (n = 23 trials) Evidence B source
  CYP1A2 activity +20-40%, GST-alpha +15-35%
• NIH advises people on warfarin to keep vitamin K intake from foods like broccoli consistent rather than avoid them, because sudden changes alter the drug's effect. — People taking warfarin and similar vitamin K antagonists (n = -) Evidence E source
  Consistent intake recommended; sudden changes can increase or decrease anticoagulant effect

What people believe that the data does not support

• No trial we found tested broccoli and cauliflower eaten together, cauliflower alone has almost no trial data, and neither US nor EU registers hold a health claim for the pair. — - (n = -) Evidence E source
  Corpus by pair name: 4 records, none on the pair as a dish; USDA R6 0; CoFID 0; 21 CFR 0; EU register 0

Who this works differently for

• In a crossover trial in 10 people eating 11 oz (300 g) of broccoli soup with its enzyme deactivated, only 2% to 15% of the glucoraphanin eaten came out as sulforaphane, varying widely between individuals. — 10 participants, three-phase double-blind crossover, 300 g soup from three broccoli genotypes (n = 10) Evidence B source
  24 h sulforaphane excretion 2-15% of glucoraphanin consumed; 3- to 5-fold higher circulating sulforaphane with high-glucoraphanin broccoli

The bottom line

The same cup gives about 74 calories, 55 mg vitamin C, 75 micrograms folate and 4.5 g fiber, with 216 mg sodium in the US recipe made with added fat and salt. Cooking changes how much sulforaphane you get from broccoli. In a crossover trial in 12 adults, adding 1 g of powdered brown mustard to 7.1 oz (200 g) of cooked broccoli raised a urine marker of sulforaphane from 9.8 to 44.7 micromol per gram of creatinine. That is a measure of uptake, and nobody tested what it means for health. People differ a great deal here. In 10 people eating 11 oz (300 g) of broccoli soup, between 2 and 15 percent of the glucoraphanin they ate came out as sulforaphane over 24 hours. Observational data from 12 cohort studies of 699,482 people link eating more broccoli with 11 percent lower cancer risk (RR 0.89, 0.82 to 0.96). Across 89 observational studies of cruciferous vegetables, each extra 50 g a day up to 75 g was linked to about 7 percent lower risk of digestive cancers. Those are associations that may partly reflect how people who eat vegetables live. If you take warfarin or a similar anticoagulant, NIH advises keeping your vitamin K intake from foods like broccoli steady rather than cutting them out, because sudden changes can strengthen or weaken the drug.

Sources

1. brcf-dr2-08 · dataset
   Broccoli and cauliflower, cooked, fat added (fdc_id 2710032): Energy 46 KCAL per 100 g · Vitamin C, total ascorbic acid 34.6 MG · Vitamin K (phylloquinone) 50.5 UG · Folate, total 47 UG · Fiber, total dietary 2.8 G · Sodium, Na 135 MG
   USDA FoodData Central survey foods (FNDDS), release 2024-10-31, Broccoli and cauliflower, cooked, fat added, food code 75330060, FDC 2710032 · checked 2026-10-02
2. brcf-dr2-07 · meta-analysis of observational studies
   In comparison to the lowest consumption categories, the highest consumption categories of CV were associated with a lower risk for all GI cancers [rate ratio (RR): 0.81, 95% confidence interval (95% CI) 0.76-0.87]. Compared to a CV intake of 75 g/day, subjects with CV intake <75 g/day experienced a 7% reduction in risk (RR: 0.93; 95% CI: 0.84-0.96) for each 50 g increase in consumption.
   Crit Rev Food Sci Nutr, 2024 · checked 2026-10-02
3. brcf-dr2-09 · dataset
   Broccoli and cauliflower, cooked, fat added (FNDDS 75330060, fdc_id 2710032): 1 cup 160 g
   USDA FoodData Central survey foods (FNDDS), release 2024-10-31, FDC 2710032 portions · checked 2026-10-02
4. brcf-dr2-04 · controlled trial
   The threshold K(1) dose causing a statistically significant lowering of the INR was 150 microg/day. In 25% of the participants the INR change was regarded as clinically relevant at a vitamin K intake of 150 microg/day.
   Blood, 2004 · checked 2026-10-02
5. brcf-dr2-01 · RCT
   When study subjects ingested cooked broccoli alone, mean urinary SF-NAC excreted was 9.8 ± 5.1 μmol per g creatinine, and when cooked broccoli was consumed with mustard powder, this increased significantly to 44.7 ± 33.9 μmol SF-NAC per gram creatinine.
   Mol Nutr Food Res, 2018 · checked 2026-10-02
6. brcf-dr2-06 · meta-analysis of observational studies
   The results suggest an inverse association between broccoli consumption and the risk of cancer both in case-control studies (OR: 0.64, 95% CI from 0.58 to 0.70, p < 0.001; Q = 35.97, p = 0.072, I2 = 30.49%-moderate heterogeneity; τ2 = 0.016) and cohort studies (RR: 0.89, 95% CI from 0.82 to 0.96, p = 0.003; Q = 13.51, p = 0.333, I2 = 11.21%-low heterogeneity; τ2 = 0.002).
   Nutrients, 2024 · checked 2026-10-02
7. brcf-dr2-03 · meta-analysis
   The meta-analyses performed demonstrated a significant effect on CYP1A2 and glutathione S-transferase-alpha (GST-α), with consumption of Cruciferae increasing the activities of these enzymes by 20-40% and 15-35%, respectively.
   Clin Pharmacol Ther, 2020 · checked 2026-10-02
8. brcf-dr2-05 · fact sheet
   People taking warfarin and similar anticoagulants need to maintain a consistent intake of vitamin K from food and supplements because sudden changes in vitamin K intakes can increase or decrease the anticoagulant effect [45].
   NIH Office of Dietary Supplements, Vitamin K Health Professional Fact Sheet · checked 2026-10-02
9. brcf-dr2-10 · register
   broccoli and cauliflower: corpus 4 (7491293, 7549804, 26581827, 18759955) · axis 2, 3, 6, 8 slices 0 · retention R6 0 (FDC does not know the food) · CoFID 0 · 21 CFR 0 · EU register 0
   Bioma corpus search 2026-10-02 (PubMed snapshot pubmed:469385), USDA R6 2007, CoFID 2021, 21 CFR 101, EU register snapshot 2026-09-21 · checked 2026-10-02
10. brcf-dr2-02 · RCT
    The percentage of sulforaphane excreted in 24 h relative to the amount of glucoraphanin consumed varies among volunteers from 2 to 15%, but does not depend on the broccoli genotype.
    Mol Nutr Food Res, 2018 · checked 2026-10-02