Mustard greens: a vitamin K vegetable that matters most on warfarin

In a randomized trial in patients on stable warfarin, 9 of 13 who ate vitamin K rich vegetables for 7 days had clotting activity above the therapeutic level (69 percent, 95% CI 39 to 91). They ate a median 1100 mcg of vitamin K a day, in a 1991 study with small groups. Mustard greens are that kind of vegetable. Raw, they hold 257.5 mcg of vitamin K per 3.5 oz (100 g) in a single USDA record with no spread between samples, and a cup of raw leaves weighs 2 oz (56 g). A cup of cooked greens weighs 4.9 oz (140 g). The working answer on warfarin is a steady intake. A systematic review of 2 dietary trials and 9 observational studies found conflicting evidence that dietary vitamin K moves blood clotting, pooled no numbers, and concluded that cutting vitamin K out does not seem a valid way to improve anticoagulation. NIH ODS gives the same advice: keep vitamin K intake consistent, because sudden changes can raise or lower the drug's effect.

The numbers, per 3.5 oz (100 g)

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

How much is actually in it

• Raw mustard greens contain about 257.5 mcg of vitamin K, 70 mg of vitamin C and 0.165 mg of copper per 3.5 oz (100 g) in USDA data. — USDA reference sample Evidence E source
  Per 100 g raw: vitamin K 257.5 mcg, vitamin C 70 mg, copper 0.165 mg; vitamin K across 5 USDA entries 257.5-592.7 mcg

What a real portion looks like

• In the US food survey database, one cup of raw mustard greens weighs 2 oz (56 g) and one cup of fresh cooked greens without fat weighs 4.9 oz (140 g). — US dietary survey portions Evidence E source
  Raw: 1 cup = 56 g, quantity not specified = 28 g; cooked no fat: 1 cup = 140 g, quantity not specified = 70 g

What your body absorbs

• In a crossover trial in 36 younger and older adults, 5 days of broccoli supplying 377 mcg of phylloquinone a day raised vitamin K status as much as fortified oil supplying 417 mcg. — 36 younger and older men and women, three 15-day residency periods in a metabolic unit (n = 36) Evidence B source
  No significant difference in plasma phylloquinone or %ucOC between broccoli and fortified oil diets, in either age group
• In a randomized trial in 12 women, absorption of phylloquinone from salad vegetables rose in a straight line with soybean oil in the dressing from 0 to 32 g and was highest at 32 g. — 12 women, 5 vegetable salads with 0, 2, 4, 8 or 32 g soybean oil (n = 12) Evidence B source
  Linear dose-response of chylomicron phylloquinone AUC across 0-32 g oil; highest absorption at 32 g (P < 0.002); wide individual variation
• According to NIH ODS, phylloquinone in leafy greens is bound to chloroplasts, and the body absorbs only 4% to 17% as much from spinach as from a tablet. — general population Evidence E source
  4-17% relative absorption from spinach versus tablet; eating fat with vegetables improves absorption

What cooking and storage change

• For greens boiled in a little water and drained, the USDA retention table keeps about 60% of vitamin C and 65% of folate, but 95% of calcium, iron and copper. — Vegetables and Vegetable Products group, greens boiled in little water, drained Evidence E source
  Retained: vitamin C 60%, folate 65%, thiamin 85%, potassium 90%, calcium 95%, iron 95%, copper 95%
• In a trial in 12 volunteers, broccoli lightly cooked (microwaved 2 minutes) yielded about 3 times more sulforaphane in the body than broccoli fully cooked (5.5 minutes). — 12 healthy volunteers, 150 g broccoli microwaved 2.0 or 5.5 min (n = 12) Evidence B source
  About 3-fold higher estimated sulforaphane yield after lightly cooked versus fully cooked broccoli

Safety, limits and interactions

• According to NIH ODS, people taking warfarin need a consistent vitamin K intake because sudden changes can raise or lower the anticoagulant effect. — people taking warfarin or similar anticoagulants Evidence E source
  Sudden changes in vitamin K intake can increase or decrease the anticoagulant effect
• In a Singapore case-control study, eating salted mustard greens 4 or more times a week was linked with 2.7 times the odds of nasopharyngeal carcinoma. — Singapore Chinese, 200 cases and 406 hospital controls (n = 606) Evidence C source
  OR 2.7 for salted mustard greens (kiam chye) 4 or more times per week

What people believe that the data does not support

• A systematic review of 2 dietary trials and 9 observational studies found conflicting evidence on the effect of dietary vitamin K on coagulation and did not support restricting dietary vitamin K on vitamin K antagonists. — patients on vitamin K antagonists in 11 clinical studies, literature to October 2015 (n = 11 studies) Evidence C source
  Conflicting evidence on coagulation response; restricting dietary vitamin K not a valid strategy to improve anticoagulation

Who this works differently for

• In a randomized trial in patients on stable warfarin, 9 of 13 (69%) who ate vitamin K rich vegetables for 7 days reached clotting activity above the therapeutic level. — patients on stable warfarin therapy, vitamin K rich vegetables for 1, 2 or 7 days (median 1100 mcg vitamin K a day) (n = 37) Evidence B source
  7 days: 69% (95% CI 39-91%) exceeded the therapeutic level; 1 day: 40% (95% CI 5-85%); 2 days: 43% (95% CI 10-86%); no change on vitamin K poor vegetables
• Among 102 low-income mothers in north Florida, being Black was positively associated with eating collard or mustard greens. — 102 low-income mothers (51 Black, 51 white) at an urban family practice center (n = 102) Evidence C source
  Positive association of Black race with collard/mustard greens consumption

What is still unknown

• When measured by HPLC, cooked mustard greens had lower vitamin C than listed in national food databases, so database values may overstate intake. — US foods analyzed by HPLC versus two national databases Evidence C source
  HPLC values lower than database values for cooked collard and mustard greens

The bottom line

How much of that vitamin K you absorb is an open question for this leaf. Nobody we found measured mustard greens directly. NIH ODS says the body takes up only 4 to 17 percent as much vitamin K from spinach as from a tablet. In a crossover trial in 36 younger and older adults, 377 mcg a day from broccoli for 5 days raised blood vitamin K about as well as 417 mcg from fortified oil, with no significant difference. Fat helps. In 12 women eating salads, absorption rose in a straight line with soybean oil in the dressing from 0 to 32 g and was highest at 32 g, with wide differences between people. Boiling costs some vitamins and spares the minerals. The USDA retention table, built in 1975 for greens as a group, keeps about 60 percent of vitamin C and 65 percent of folate after boiling in a little water and draining, against 95 percent of calcium, iron and copper. The 70 mg of vitamin C per 3.5 oz (100 g) listed for raw leaves may itself run high. A 1993 HPLC analysis found lower vitamin C in cooked mustard greens than the national databases list, without giving the size of the gap. In 12 volunteers, broccoli microwaved for 2 minutes gave about 3 times more sulforaphane in the body than broccoli microwaved for 5.5 minutes, a result from a related brassica rather than this leaf. Two groups should take care. People on warfarin or a similar drug should keep the amount of greens they eat steady from week to week rather than swinging between none and a lot. Salted, preserved mustard greens are a separate food. In a Singapore case-control study of 200 people with nasopharyngeal cancer and 406 hospital controls, eating salted mustard greens 4 or more times a week was linked with 2.7 times the odds of the cancer. That is an association recalled after diagnosis, and it says nothing about fresh leaves.

Sources

1. mgr-daily-r3-01 · food composition dataset
   Mustard greens, raw; vitamin K 257.5 ug; vitamin C 70 mg; copper 0.165 mg (per 100 g)
   USDA FoodData Central SR Legacy, Mustard greens, raw, FDC 169256 · checked 2026-10-01
2. mgr-daily-r3-02 · food composition dataset
   Mustard greens, raw; 1 cup: 56 g; Quantity not specified: 28 g. Mustard greens, fresh, cooked, no added fat; 1 cup: 140 g; Quantity not specified: 70 g
   USDA FoodData Central survey (FNDDS) 2024-10-31, food codes 72122100 and 72122211, fdc_id 2709606 and 2709607 · checked 2026-10-01
3. mgr-daily-r3-04 · randomized crossover trial
   In a crossover design with three 15-d residency periods in a metabolic unit, younger and older men and women (n = 36) consumed a mixed diet containing 100 microg phylloquinone/d. During 2 residency periods, the mixed diet was supplemented for 5 d with either broccoli (377 microg phylloquinone/d; broccoli diet) or phylloquinone-fortified oil (417 microg/d; oil diet). ... Overall, the response to broccoli supplementation was not significantly different from the response to the fortified oil in either age group.
   Am J Clin Nutr, 1999 · checked 2026-10-01
4. mgr-daily-r3-05 · randomized trial
   Design: Women (n = 12) each consumed 5 vegetable salads with salad dressings containing 0, 2, 4, 8, or 32 g soybean oil. ... Results: Across the entire 0-32-g range, soybean oil was linearly related to the chylomicron AUC and Cmax values for α-carotene, lycopene, phylloquinone, and retinyl palmitate. ... Absorption of all carotenoids and fat-soluble vitamins was highest with 32 g oil (P < 0.002).
   Am J Clin Nutr, 2017 · checked 2026-10-01
5. mgr-daily-r3-06 · fact sheet
   Phylloquinone in plant foods is tightly bound to chloroplasts, so it is less bioavailable than that from oils or dietary supplements [1]. For example, the body absorbs only 4% to 17% as much phylloquinone from spinach as from a tablet [2]. Consuming vegetables at the same time as some fat improves phylloquinone absorption from the vegetables, but the amount absorbed is still lower than that from oils.
   NIH Office of Dietary Supplements, Vitamin K Fact Sheet for Health Professionals · checked 2026-10-01
6. mgr-daily-r3-03 · nutrient retention table
   VEG,GREENS,BOILD,LITTLE WATER DRAIN: vitamin_c_mg 60%; folate_total_ug 65%; thiamin_mg 85%; potassium_mg 90%; calcium_mg 95%; iron_mg 95%; copper_mg 95%
   USDA Table of Nutrient Retention Factors, Release 6 (2007), code 3004 · checked 2026-10-01
7. mgr-daily-r3-10 · randomized trial
   Volunteers (n 12) were each offered a meal, with or without beef, together with 150 g lightly cooked broccoli (microwaved 2.0 min) or fully cooked broccoli (microwaved 5.5 min), or a broccoli seed extract. ... The estimated yield of sulforaphane in vivo was about 3-fold higher after consumption of lightly cooked broccoli than fully cooked broccoli.
   Br J Nutr, 2007 · checked 2026-10-01
8. mgr-daily-r3-08 · 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 2026-10-01
9. mgr-daily-r3-11 · case-control study
   The association between the consumption of preserved foods in infancy, childhood and adulthood and the risk of nasopharyngeal carcinoma was investigated in a case-control study among Singapore Chinese: 200 cases (73% male) were compared with 406 hospital controls (71% male). Significantly increased risks were observed in association with frequent adult consumption of salted soy beans (OR 7.3 for consumption 4 or more times per week, compared with never), canned pickled vegetables (p = 0.01; OR 4.5 for 4 or more times per week), "sze chuan chye", a salted Chinese tuber, (OR 2.4 for 4 or more times per month) and "kiam chye", salted mustard greens (OR 2.7 for 4 or more times per week).
   Int J Cancer, 1994 · checked 2026-10-01
10. mgr-daily-r3-09 · systematic review
    Two dietary interventional trials and 9 observational studies were included. We found conflicting evidence on the effect of dietary intake of vitamin K on coagulation response. ... The available evidence does not support current advice to modify dietary habits when starting therapy with VKAs. Restriction of dietary vitamin K intake does not seem to be a valid strategy to improve anticoagulation quality with VKAs.
    Medicine (Baltimore), 2016 · checked 2026-10-01
11. mgr-daily-r3-07 · randomized trial
    Patients on stable anticoagulant treatment were randomized to either 1 (n = 5), 2 (n = 7) or 7 (n = 13) d with high intake of vitamin-K-rich vegetables (median daily vitamin K intake 1100 micrograms) or high intake of vitamin-K-poor vegetables (daily vitamin K intake 135 micrograms) for 6 d (n = 7), or habitual diet supplemented with 1000 micrograms of phytomenadione daily (n = 5). Nine patients (69%; 95% CI, 39-91%) who consumed vitamin-K-rich vegetables for 7 d reached activities above the therapeutic level.
    J Intern Med, 1991 · checked 2026-10-01
12. mgr-daily-r3-12 · cross-sectional study
    Ethnic differences in self-reported dietary intake between blacks and whites (participants and non-participants in the Food Stamp program) were studied in a group of 102 low-income mothers presenting themselves for treatment at an urban family practice center. ... Being a member of the black race was positively associated with consumption of chicken, hot dogs, collard/mustard greens, and white rice.
    J Am Diet Assoc, 1988 · checked 2026-10-01
13. mgr-daily-r3-13 · food analysis
    HPLC values were lower in four of the five highest vitamin C contributors to the US diet (orange juice, grapefruit, tomatoes and tomato juice, and potatoes), as well as in broccoli, red peppers, and cooked collard and mustard greens, compared with values from the other databases.
    Am J Clin Nutr, 1993 · checked 2026-10-01