Bok choy and cabbage: one family, mostly measured as cabbage

The strongest evidence here is about medicines. A meta-analysis of 23 dietary intervention trials found that diets rich in cruciferous vegetables, cabbage among them, raised the activity of the drug-metabolizing enzyme CYP1A2 by 20 to 40 percent. Bok choy was not one of the vegetables tested, and what this means for any particular drug is unclear. On composition the two look alike. Raw bok choy averages 30 mg of vitamin C and 62 mg of calcium per 3.5 oz (100 g) across 8 US retail samples, and vitamin C swung from 16 to 44 mg between those samples. UK tables give raw Chinese cabbage 21 mg of vitamin C and 54 mg of calcium per 3.5 oz (100 g), an entry that may describe napa cabbage. We found no study comparing bok choy with head cabbage for any health outcome, so each number below says which of the two it belongs to.

How much is actually in it

• Raw bok choy averages 30 mg vitamin C and 62 mg calcium per 3.5 oz (100 g) in USDA analyses, and vitamin C ranged from 16 to 44 mg across 8 samples. — USDA Foundation Foods, Cabbage, bok choy, raw, 8 samples (n = 8 samples) Evidence E source
  Vitamin C 30.3 mg (range 16.2-43.8); calcium 61.93 mg (range 48.8-100.0); potassium 227.8 mg (range 165-280) per 3.5 oz (100 g)
• UK food tables list raw Chinese cabbage at 12 calories, 21 mg vitamin C, 54 mg calcium and 77 ug folate per 3.5 oz (100 g), a lower vitamin C value than the US bok choy average. — CoFID 2021, Cabbage, Chinese, raw (13-187) Evidence E source
  Per 100 g: energy 12 calories; vitamin C 21 mg; calcium 54 mg; potassium 230 mg; folate 77 ug; iron 0.60 mg
• A worldwide meta-analysis of produce samples ranked bok choy third among vegetables for nitrate and nitrite, at about 3400 mg per kg. — Vegetable and fruit samples worldwide Evidence C source
  Bok choy 3407.40 mg/kg (95% CI 2841.39-3973.42); rocket 4825.15; mizuna 3500

What a real portion looks like

• In the US survey database a cup of raw Chinese cabbage weighs 3.2 oz (90 g), a single leaf 15 g and a whole head about 840 g. — FNDDS Cabbage, Chinese, raw (75104000) Evidence E source
  1 cup 90 g; 1 leaf 15 g; 1 head 840 g; quantity not specified 45 g

What your body absorbs

• In a randomized crossover trial in 25 adults, 1.8 oz (50 g) of raw cabbage daily for 3 days produced less urinary DIM, a marker of indole-3-carbinol uptake, than high-glucobrassicin Brussels sprouts. — 25 adults, 50 g raw Brassica vegetable once daily for 3 days, crossover (n = 25) Evidence B source
  Urinary DIM 8.73 pmol/mg creatinine higher after Brussels sprouts than cabbage (95% CI 5.36-12.10)
• In a trial of 45 adults eating cabbage and/or Brussels sprouts, uptake of indole-3-carbinol rose with glucobrassicin dose but plateaued between 200 and 300 umol. — 45 adults, vegetables at one of seven glucobrassicin doses (25-500 umol) once daily for 2 days (n = 45) Evidence B source
  Dose-response R2 = 0.68; plateau at 200-300 umol glucobrassicin

What cooking and storage change

• Under the USDA table for leafy greens boiled in water to cover and drained, about 55% of vitamin C and 60% of folate are retained, while calcium and iron keep 95%. — USDA Table of Nutrient Retention Factors, Vegetables and Vegetable Products, greens boiled water cover drained (3005) Evidence E source
  Retained: vitamin C 55%, folate 60%, thiamin 80%, potassium 85%, calcium 95%, iron 95%

What it does to your health

• Observational data pool high intake of broccoli and cabbage with a 36% lower risk of gastric cancer in a meta-analysis of 89 studies. — Observational studies, 81 articles covering 89 studies (n = 89 studies) Evidence C source
  Gastric cancer RR 0.64 (95% CI 0.47-0.87); gallbladder cancer RR 0.46 (0.29-0.75)
• An umbrella review of 76 meta-analyses rated cabbage among only 8 protective factors with strong epidemiologic evidence for gastric cancer. — Meta-analyses of observational studies, 137 associations in 76 articles (n = 76 articles) Evidence C source
  Cabbage among 10 of 137 associations graded strong

Safety, limits and interactions

• A meta-analysis of 23 dietary intervention trials found that diets rich in cruciferous vegetables, including cabbage, raised CYP1A2 drug-metabolizing activity by 20 to 40%. — Humans in 23 dietary intervention trials with drug metabolism end points (broccoli, Brussels sprout, cabbage, cauliflower, radish, watercress) (n = 23 trials) Evidence A source
  CYP1A2 activity +20-40%; GST-alpha activity +15-35%
• A meta-analysis of Ethiopian studies found cabbage among the vegetables most often contaminated, with parasites in 52.9% and bacteria in 20.0% of samples. — 29 cross-sectional studies, 6659 vegetables and fruits, Ethiopia (n = 6659 samples) Evidence C source
  Cabbage parasitic contamination 52.9%; bacterial 20.0%

What people believe that the data does not support

• The EU did not authorize the claim that cruciferous vegetables such as cabbage are particularly rich in compounds that protect DNA from oxidative damage or help eliminate toxins. — EU Register on nutrition and health claims, POL-HC-6819 Evidence E source
  Status: non-authorized

Who this works differently for

• In 17 patients with cabbage allergy, five reported anaphylaxis, and most were also sensitized to mugwort pollen, mustard and peach through the lipid transfer protein Bra o 3. — 17 patients allergic to cabbage, Spain, skin prick tests and double-blind placebo-controlled food challenges (n = 17) Evidence C source
  5 of 17 anaphylactic reactions; Bra o 3 skin test positive in 12 of 14 (86%)
• Among 418 Ethiopian schoolchildren with high goitre prevalence, frequent cabbage consumption was associated with higher odds of goitre (AOR 7.74). — 418 children aged 6-12 years, Anchar district, Eastern Ethiopia (n = 418) Evidence C source
  AOR 7.74 (95% CI 4.48-13.39) for frequency of cabbage consumption

The bottom line

The cancer findings are observational. Pooled data from 89 studies link the highest intake of broccoli and cabbage, counted together, with a 36 percent lower risk of stomach cancer (RR 0.64, 95% CI 0.47 to 0.87) compared with the lowest intake, and confounding by other habits is possible. An umbrella review of 76 articles graded cabbage among 8 protective factors with strong epidemiologic evidence for stomach cancer. That grade describes how consistent the observational data are and does not establish cause. Two small trials looked at uptake. In a randomized crossover trial in 25 adults, 1.8 oz (50 g) of raw cabbage a day for 3 days left less urinary DIM, a marker of indole-3-carbinol uptake, than the same weight of Brussels sprouts (8.73 pmol/mg creatinine less, 95% CI 5.36 to 12.10). The cabbage was a low-glucobrassicin variety and DIM measures uptake only. In 45 adults eating cabbage and Brussels sprouts mixed, uptake rose with glucobrassicin dose and levelled off between 200 and 300 umol, with cabbage never measured on its own. Boiling changes the vitamins more than the minerals. The USDA factor for leafy greens boiled and drained keeps about 55 percent of vitamin C and 60 percent of folate, while calcium and iron keep 95 percent. It is a group factor dating from 1975 and was never measured on bok choy or cabbage. In the US survey database a cup of raw Chinese cabbage weighs 3.2 oz (90 g) and one leaf 15 g. Composition data pooled worldwide put bok choy third among vegetables for nitrate and nitrite, at about 3400 mg per kg (95% CI 2841 to 3973), and that analysis did not look at health effects at all. The EU refused to authorize a claim that cruciferous vegetables such as cabbage are especially rich in compounds that protect DNA or help the body remove toxins. Refusal means the evidence was judged insufficient at assessment. Who should be careful. If you take a prescription drug and plan a large, lasting change in how much cabbage you eat, the CYP1A2 trials are a reason to tell whoever prescribes it. In a Spanish series of 17 patients allergic to cabbage, five had anaphylaxis, and most were also sensitized to mugwort pollen, mustard and peach. Among 418 schoolchildren in an iodine-poor district of eastern Ethiopia, frequent cabbage eating went with higher odds of goitre (adjusted odds ratio 7.74, 95% CI 4.48 to 13.39), a cross-sectional link that does not show cause. Pooled Ethiopian studies of raw unwashed market produce found parasites on 52.9 percent of cabbage samples, a figure from one country that says nothing about washed or cooked cabbage. We have no card on pregnancy, or on the thyroid in people who get enough iodine.

Sources

1. bkcb-daily-r5-01 · dataset
   Cabbage, bok choy, raw: Vitamin C, total ascorbic acid 30.3 MG, range 16.2-43.8 (median 29.2), 8 samples; Calcium, Ca 61.93 MG, range 48.8-100.0 (median 56.05), 8 samples; Potassium, K 227.8 MG, range 165.0-280.0 (median 244.0), 8 samples
   USDA FoodData Central, Foundation Foods, release 2026-04-30 · checked 2026-10-01
2. bkcb-daily-r5-02 · dataset
   Cabbage, Chinese, raw (13-187): Energy 12 kcal; Vitamin C 21 mg; Calcium 54 mg; Potassium 230 mg; Folate 77 ug; Iron 0.60 mg
   CoFID 2021, Public Health England, OGL v3.0 · checked 2026-10-01
3. bkcb-daily-r5-11 · meta-analysis
   The highest concentration (mean and 95%CI) of nitrate/nitrite was determined in Rocket (4825.15; 3044.14-6606.16), Mizuna (3500; 2702.48-4297.52), and Bok choy (3407.40; 2841.39-3973.42) in vegetable group
   Ecotoxicol Environ Saf, 2023 · checked 2026-10-01
4. bkcb-daily-r5-04 · dataset
   Cabbage, Chinese, raw (FNDDS 75104000): 1 cup 90 g; 1 leaf 15 g; 1 head 840 g; Quantity not specified 45 g
   USDA FoodData Central, FNDDS survey foods, release 2024-10-31 · checked 2026-10-01
5. bkcb-daily-r5-06 · 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 2026-10-01
6. bkcb-daily-r5-07 · 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 2026-10-01
7. bkcb-daily-r5-03 · dataset
   VEG,GREENS,BOILED,WATER COVER DRAIN (3005): vitamin_c_mg 55%; folate_total_ug 60%; thiamin_mg 80%; potassium_mg 85%; calcium_mg 95%; iron_mg 95%
   USDA Table of Nutrient Retention Factors, Release 6, 2007 · checked 2026-10-01
8. bkcb-daily-r5-09 · meta-analysis
   High intake of broccoli and cabbage was associated with a decreased risk of gastric cancer (RR: 0.64; 95% CI: 0.47-0.87) and gallbladder cancer (RR: 0.46; 95% CI: 0.29-0.75).
   Crit Rev Food Sci Nutr, 2024 · checked 2026-10-01
9. bkcb-daily-r5-10 · umbrella review
   Only 10 associations had strong epidemiologic evidence, including 2 risk factors (waist circumference and bacon), and 8 protective factors (dietary total antioxidant capacity, vegetable fat, cruciferous vegetable, cabbage, total vitamin, vitamin A, vitamin C, and years of fertility);
   Front Public Health, 2022 · checked 2026-10-01
10. bkcb-daily-r5-05 · meta-analysis
    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 2026-10-01
11. bkcb-daily-r5-12 · meta-analysis
    Lettuce (61.0%), salad (57.4%), spinach (54.2%), and cabbage (52.9%), were the vegetables most contaminated by parasites, while salad (73.8%), green pepper (35.3%), lettuce (26.0%), and cabbage (20.0%), were the most contaminated by bacteria.
    BMC Infect Dis, 2025 · checked 2026-10-01
12. bkcb-daily-r5-14 · regulatory decision
    POL-HC-6819 Brassicaceae (Cruciferae) (Common Name : Botanical family that include broccoli, couliflower, cabbage, Bruxelles sprouts etc.) Are particularly rich of protective compounds that protect cells and DNA from oxidative damage/are particularly rich of compounds that help our body to eliminate toxic substances Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-6819, snapshot 2026-09-21 · checked 2026-10-01
13. bkcb-daily-r5-08 · prospective clinical study
    Five of them referred anaphylactic reactions when eating cabbage, and in another 5 patients, cabbage allergy was further confirmed by double-blind placebo-controlled food challenge. Most of them showed associated sensitizations to mugwort pollen, mustard, and peach.
    J Allergy Clin Immunol, 2006 · checked 2026-10-01
14. bkcb-daily-r5-13 · cross-sectional
    frequency of cabbage consumption (AOR = 7.74, CI: 4.48, 13.39)
    PLoS One, 2019 · checked 2026-10-01