Brussels sprouts: a vitamin C vegetable that also nudges drug enzymes

The best evidence touching Brussels sprouts is about how the body handles drugs. A meta-analysis of 23 dietary intervention trials found that cruciferous vegetables, Brussels sprouts among them, raised the activity of the enzyme CYP1A2 by 20 to 40 percent and GST-alpha by 15 to 35 percent. Not every included trial was randomized and no specific drug was tested. As food, the sprout is a dependable source of vitamin C. Eight raw US samples averaged 142.9 mg per 3.5 oz (100 g), anywhere from 84.6 to 197 mg, with season and storage unrecorded. The UK table puts raw sprouts at 115 mg and boiled ones at 40 mg, and gives 153 mcg of vitamin K1 raw. The DNA damage studies are tiny. In 10 healthy men, 11 oz (300 g) of cooked sprouts a day for 3 weeks lowered a urinary marker of oxidative DNA damage by 28 percent, with five men per group and a marker standing in for cancer, which nobody measured.

The numbers, per 3.5 oz (100 g)

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

How much is actually in it

• In 8 USDA Foundation samples, raw Brussels sprouts held 84.6 to 197 mg vitamin C per 3.5 oz (100 g), with a mean of 142.9 mg. — USDA FoodData Central Foundation Foods, Brussels sprouts, raw, 8 samples Evidence E source
  Vitamin C 142.9 mg/100 g, range 84.6-197.0, median 146.0
• The UK composition table lists raw Brussels sprouts at 115 mg vitamin C and 153 mcg vitamin K per 3.5 oz (100 g), falling to 40 mg and 127 mcg when boiled. — CoFID 2021, codes 13-177 (raw) and 13-630 (boiled in unsalted water) Evidence E source
  Raw: 42 calories, vitamin C 115 mg, folate 135 mcg, vitamin K1 153 mcg; boiled: 32 calories, vitamin C 40 mg, folate 124 mcg, vitamin K1 127 mcg, fiber 3.2 g per 3.5 oz (100 g)
• According to NIH ODS, Brussels sprouts are among the best vitamin C sources, and steaming or microwaving may lessen cooking losses. — general population Evidence E source
  Qualitative

What a real portion looks like

• In the US dietary survey a cup of cooked Brussels sprouts is coded at 155 g and one sprout at 20 g. — USDA FNDDS, Brussels sprouts, fresh, cooked, no added fat (code 75209011) Evidence E source
  1 cup 155 g; 1 sprout 20 g; quantity not specified 78 g

What your body absorbs

• In a non-randomized trial in 8 people, 300 g Brussels sprouts a day raised serum vitamin C by 37% and cut hydrogen peroxide DNA damage in lymphocytes by 39%. — n = 8 (n = 8) Evidence C source
  Serum vitamin C +37%; H2O2-induced DNA damage -39%; PhIP-induced DNA migration -97%
• In a crossover RCT in 25 adults, 1.8 oz (50 g) of raw Brussels sprouts a day led to higher urinary DIM, a marker of indole-3-carbinol uptake, than the same amount of low-glucobrassicin cabbage. — Twenty-five subjects (n = 25) Evidence B source
  Urinary DIM +8.73 pmol/mg creatinine (95% CI 5.36 to 12.10)
• In a small human micro-dosing trial, 50 g Brussels sprouts a day for a week reduced plasma levels of a benzo[a]pyrene microdose by 56-67%. — Volunteers Evidence C source
  Total [14C] recovered from plasma -56 to -67%

What cooking and storage change

• By the USDA retention table for other vegetables boiled in water to cover and drained, about 75% of vitamin C and 65% of folate remain. — USDA Table of Nutrient Retention Factors R6, group Vegetables and Vegetable Products, method 3775 Evidence E source
  Vitamin C retention 75%, folate 65%

What it does to your health

• In a small controlled trial in 10 healthy men, eating 11 oz (300 g) of cooked Brussels sprouts a day for 3 weeks lowered a urinary marker of oxidative DNA damage by 28%. — 10 healthy, male, non-smoking volunteers (n = 10) Evidence B source
  Urinary 8-oxodG -28% (P = 0.039); control unchanged
• In a crossover RCT in 10 healthy adults, 300 g cooked Brussels sprouts a day for a week raised rectal levels of the enzymes GST-alpha by 30% and GST-pi by 15%. — Ten healthy non-smoking volunteers (n = 10) Evidence B source
  Rectal GST-alpha +30%, GST-pi +15%; overall GST activity unchanged
• Observational data from the MESA cohort link eating the broccoli category, which includes Brussels sprouts, to lower inflammation and lower mortality odds. — Multi-Ethnic Study of Atherosclerosis (MESA) Evidence C source
  Lower IL-6, D-dimer and mortality odds; no size in abstract

Safety, limits and interactions

• By a meta-analysis of 23 dietary intervention trials, cruciferous vegetables including Brussels sprouts raised the activity of the drug-metabolizing enzymes CYP1A2 by 20-40% and GST-alpha by 15-35%. — Twenty-three dietary intervention trials (n = 23 trials) Evidence B source
  CYP1A2 +20-40%, GST-alpha +15-35%

What people believe that the data does not support

• In an 8-week RCT in 78 premenopausal women, 40 g a day of broccoli or Brussels sprouts did not change the urinary estrogen metabolite ratio linked to breast cancer risk. — 78 healthy premenopausal women (38-50 y) (n = 78) Evidence B source
  No treatment effect (P = 0.9)
• In a UK survey of 516 adults, 23% believed Brussels sprouts cause flatulence, though flatulence worried few respondents. — 516 respondents (85% female, median age 38 years) (n = 516) Evidence C source
  23% attribute flatulence to Brussels sprouts

Who this works differently for

• In a crossover RCT in 10 volunteers eating 11 oz (300 g) Brussels sprouts a day for a week, the oxidative DNA damage marker fell in 4 of 5 men but did not change in women. — Ten non-smoking volunteers (five males and five females) (n = 10) Evidence B source
  Reduction in 4 of 5 males; no effect in females
• In a crossover RCT, a week of 11 oz (300 g) cooked Brussels sprouts a day raised plasma GST-alpha 1.5-fold in men but not in women. — Five male and five female non-smoking volunteers (n = 10) Evidence B source
  Plasma GST class-alpha 1.5-fold in males (P = 0.031), not females (P = 0.317)
• According to NIH ODS, people taking warfarin need a consistent vitamin K intake, because sudden changes can raise or lower the drug's effect. — people taking warfarin and similar anticoagulants Evidence E source
  Vitamin K changes alter anticoagulant effect

What is still unknown

• In a dose-ranging trial in 45 adults eating Brussels sprouts or cabbage, urinary DIM rose with glucobrassicin dose but plateaued between 200 and 300 µmol. — Forty-five subjects (n = 45) Evidence B source
  Dose-response R2 = 0.68; plateau at 200-300 µmol glucobrassicin
• Observational data pooled from 18 cohorts found a positive, not inverse, association between Brussels sprouts intake and hypertension, based on only 2 to 5 studies. — Eighteen prospective studies (451 291 participants, 145 492 cases) (n = 451291) Evidence C source
  Positive association for Brussels sprouts (n = 2-5 studies); vegetables overall RR 1.00 per 200 g/day

The bottom line

Those 300 g are close to two cups, since the US dietary survey counts a cup of cooked sprouts as 155 g and one sprout as 20 g. The same Dutch group reported that the damage marker fell in 4 of 5 men and did not move in women, and that a blood enzyme rose 1.5-fold in men only. These are groups of five people, so the sex difference is a lead, and nobody has repeated it at scale. Two popular beliefs did not hold up. In an 8-week trial in 78 premenopausal women, 40 g a day of broccoli or Brussels sprouts did not change the urinary estrogen ratio linked to breast cancer risk (P = 0.9). In a UK survey of 516 adults, mostly women, 23 percent believed sprouts cause wind, which is a perception and was never measured. The population data are mixed. Pooled cohorts found a positive association between sprouts and high blood pressure, resting on only 2 to 5 studies with likely confounding. The US MESA cohort linked a broccoli category that lumps sprouts with cabbage, kimchi and four other foods to lower inflammation and lower mortality odds, with no size given. Boiling costs vitamin C. The USDA group factor for vegetables boiled in water and drained keeps about 75 percent of vitamin C and 65 percent of folate, a factor that was never measured on sprouts. The NIH says steaming or microwaving may lessen the loss. If you take warfarin, the NIH advises keeping vitamin K intake steady, because sudden changes can raise or lower the drug effect. Raw sprouts carry 153 mcg of vitamin K1 per 3.5 oz (100 g), so a sudden change in how many you eat is worth telling your prescriber about. The enzyme shifts above are a second reason to mention a large new habit if you take regular medication. We found no study of sprouts in pregnancy or in children.

Sources

1. brsp-daily-r1-14 · reference dataset
   Brussels sprouts, raw: Vitamin C, total ascorbic acid 142.9 mg/100 g · range 84.6-197.0 (median 146.0), 8 samples
   USDA FoodData Central, Foundation Foods, release 2026-04-30 (Brussels sprouts, raw, FDC 2685575) · checked 2026-09-29
2. brsp-daily-r1-15 · reference dataset
   CoFID 13-177 Brussels sprouts, raw: Energy 42 kcal · Folate 135 µg · Vitamin C 115 mg · Vitamin K1 153 µg | CoFID 13-630 Brussels sprouts, boiled in unsalted water: Energy 32 kcal · AOAC fibre 3.2 g · Folate 124 µg · Vitamin C 40 mg · Vitamin K1 127 µg
   CoFID 2021, Public Health England (OGL v3.0), codes 13-177 and 13-630 · checked 2026-09-29
3. brsp-daily-r1-19 · fact sheet
   The best sources of vitamin C are fruits and vegetables, especially citrus fruits, red and green peppers, kiwifruit, broccoli, strawberries, and Brussels sprouts. ... Steaming or microwaving may lessen cooking losses.
   NIH Office of Dietary Supplements, Vitamin C Fact Sheet for Health Professionals · checked 2026-09-29
4. brsp-daily-r1-17 · reference dataset
   FNDDS 75209011 Brussels sprouts, fresh, cooked, no added fat (fdc 2709881): 1 cup 155 g · 1 sprout 20 g · Quantity not specified 78 g
   USDA FNDDS 2021-2023 (FoodData Central) · checked 2026-09-29
5. brsp-daily-r1-05 · controlled trial
   After consumption of the sprouts (300 g/p/d, n = 8), a reduction of DNA-migration (97%) induced by the heterocyclic aromatic amine 2-amino-1-methyl-6-phenyl-imidazo-[4,5-b]pyridine (PhIP) was observed ... DNA-damage caused by hydrogen peroxide was significantly (39%) lower after the intervention. ... Serum vitamin C levels were increased by 37% after sprout consumption
   Mol Nutr Food Res, 2008 · checked 2026-09-29
6. brsp-daily-r1-06 · RCT
   Twenty-five subjects were fed 50 g of either raw "Jade Cross" Brussels sprouts (high glucobrassicin concentration) or "Blue Dynasty" cabbage (low glucobrassicin concentration) once daily for 3 days. ... Urinary DIM was consistently and significantly higher after Brussels sprouts feeding than after cabbage feeding, as evidenced by an average difference of 8.73 pmol/mg creatinine (95% confidence interval, 5.36-12.10; P = 0.00002).
   Cancer Epidemiol Biomarkers Prev, 2014 · checked 2026-09-29
7. brsp-daily-r1-11 · clinical trial
   Volunteers were dosed with [14C]-BaP following fourteen days on a cruciferous vegetable restricted diet, or the same diet supplemented for seven days with 50 g of BS or 300 mg of BR-DIM® prior to dosing. BS or DIM reduced total [14C] recovered from plasma by 56-67% relative to non-intervention.
   Toxicol Appl Pharmacol, 2023 · checked 2026-09-29
8. brsp-daily-r1-16 · reference dataset
   R6 3775 VEG,OTHER,BLD,WATER COVER,DRAINED: folate_total_ug 65% · vitamin_c_mg 75%
   USDA Table of Nutrient Retention Factors, Release 6 (2007), code 3775 · checked 2026-09-29
9. brsp-daily-r1-01 · RCT
   The effect of consumption of Brussels sprouts on levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) in human urine was investigated in 10 healthy, male, non-smoking volunteers. ... while the other five (sprouts group) consumed 300 g of cooked Brussels sprouts per day, at the expense of 300 g of a glucosinolate-free vegetable. ... In contrast, in the sprouts group the levels of 8-oxodG were decreased by 28% during the intervention period (P = 0.039).
   Carcinogenesis, 1995 · checked 2026-09-29
10. brsp-daily-r1-03 · RCT
    Ten healthy non-smoking volunteers were randomly assigned to two groups in a cross-over design. Five persons started on a glucosinolate-free diet (control period), while the other five consumed 300 g/day cooked Brussels sprouts, at the expense of 300 g glucosinolate-free vegetables (sprouts period). ... As a result of the dietary regimen rectal GST-alpha and -pi levels were slightly increased at the end of the sprouts period, by 30 and 15% respectively.
    Carcinogenesis, 1995 · checked 2026-09-29
11. brsp-daily-r1-13 · cohort
    Consumption of the MESA-defined food category "broccoli" (i.e., broccoli, cabbage, cauliflower, brussels sprouts, sauerkraut, and kimchee) was associated with lower inflammation and lower mortality odds.
    J Med Food, 2024 · checked 2026-09-29
12. brsp-daily-r1-08 · meta-analysis of intervention trials
    Twenty-three dietary intervention trials with drug metabolism end points were identified across Embase, Medline, and the Cochrane Controlled Register of Trials (CENTRAL). Cruciferous vegetables represented in the literature included broccoli, Brussels sprout, cabbage, cauliflower, radish, and watercress. ... 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 2026-09-29
13. brsp-daily-r1-10 · RCT
    This randomized, parallel arm, placebo-controlled, partly blinded study included 78 healthy premenopausal women (38-50 y) with screening urinary 2:16 ≤3.0. Subjects received either six capsules containing 550 mg dried Brussels sprouts and kale per capsule, 40 g daily alternating broccoli or Brussels sprouts, or placebo for eight weeks. ... In conclusion, neither cruciferous supplements nor an added vegetable serving altered urinary 2:16 in premenopausal women with eight weeks treatment.
    Int J Vitam Nutr Res, 2024 · checked 2026-09-29
14. brsp-daily-r1-12 · survey
    Of 516 respondents (85% female, median age 38 years), 72.1% reported no existing GI conditions ... The most common perceptions were that beans (34%) and Brussels sprouts (23%) cause flatulence
    Eur J Nutr, 2025 · checked 2026-09-29
15. brsp-daily-r1-02 · RCT
    Ten non-smoking volunteers (five males and five females) were randomly assigned to two groups. Five volunteers started on a diet of 300 g of glucosinolate-free vegetables whereas the other five consumed 300 g of Brussels sprouts per day. ... In four of five males a reduction in 8-oxodG was found, whereas in the fifth male the 8-oxodG excretion was high in the control period and was even much higher in the sprouts period. In females no effect of consumption of Brussels sprouts on excretion of 8-oxodG was found.
    Cancer Lett, 1997 · checked 2026-09-29
16. brsp-daily-r1-04 · RCT
    Five male and five female non-smoking volunteers were randomly assigned to two groups in a crossover design. ... At the end of the sprouts period, a significant increase (1.5-fold) in plasma class-alpha GST levels was observed in males but not in females (control versus sprouts, paired t-test; P-values 0.031 and 0.317 respectively)
    Carcinogenesis, 1995 · checked 2026-09-29
17. brsp-daily-r1-18 · 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 Fact Sheet for Health Professionals · checked 2026-09-29
18. brsp-daily-r1-07 · RCT
    Forty-five subjects consumed vegetables, a mixture of brussels sprouts and/or cabbage, at one of seven discrete dose levels of glucobrassicin ranging from 25 to 500 μmol, once daily for 2 consecutive days. ... Urinary DIM excretion increased predictably with increasing glucobrassicin dose and plateaued between 200 and 300 μmol of glucobrassicin. The association between glucobrassicin dose and urinary DIM was strong and positive (R2 = 0.68).
    Cancer Prev Res (Phila), 2016 · checked 2026-09-29
19. brsp-daily-r1-09 · meta-analysis of cohorts
    Eighteen prospective studies (451 291 participants, 145 492 cases) were included. ... Inverse associations were observed for apples or pears, blueberries, raisins or grapes, avocado, broccoli, carrots and lettuce, while positive associations were observed for cantaloupe, Brussels sprouts, cruciferous vegetables, and total and fried potatoes (n = 2-5).
    Eur J Nutr, 2023 · checked 2026-09-29