Turnip greens: a vitamin K food that matters most on warfarin

In a randomized trial of people on stable warfarin, 9 of the 13 who ate vitamin K-rich vegetables for 7 days rose above their target anticoagulation range (69 percent, 95% CI 39 to 91). Their median intake was about 1,100 mcg of vitamin K a day, a very large amount of greens, the groups were small, and the abstract does not name turnip greens among the vegetables. Raw turnip greens carry about 251 mcg of vitamin K per 3.5 oz (100 g) in a single USDA reference record. A systematic review of 2 diet trials and 9 observational studies found the evidence on dietary vitamin K and warfarin conflicting, with an effect on clotting tests seen mainly above about 150 mcg a day. Its authors concluded that cutting vitamin K out of the diet does not look like a valid way to steady warfarin treatment. For blood pressure the one trial is a null result. Over just 7 days, 38 adults with high-normal pressure added at least 300 mg a day of nitrate from green leafy vegetables, not turnip greens alone. Blood nitrate rose at least fourfold and blood pressure did not change.

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 turnip greens contain about 251 mcg of vitamin K, 60 mg of vitamin C and 579 mcg RAE of vitamin A per 3.5 oz (100 g) in USDA data. — USDA reference sample Evidence E source
  Per 100 g raw: vitamin K 251 mcg, vitamin C 60 mg, vitamin A 579 mcg RAE; vitamin K across 6 USDA entries 251-518.9 mcg

What a real portion looks like

• In a randomized crossover trial giving frozen greens including turnip greens, adults met a goal of 1 cooked cup a day on 73.2% of days and ate some greens on 88.8% of days. — 50 adults at increased colon cancer risk, 4-week greens period within a 12-week trial (n = 50) Evidence B source
  Some greens on 88.8% of days; 1 cup goal met on 73.2% of days; 96% retained
• In the US food survey database, one cup of fresh turnip greens cooked without fat weighs 5.1 oz (145 g). — US dietary survey portions Evidence E source
  1 cup = 145 g; quantity not specified = 73 g

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 and iron. — 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%

What it does to your health

• In a randomized crossover trial, adding at least 300 mg a day of nitrate from green leafy vegetables for 7 days raised blood nitrate fourfold but did not lower blood pressure. — men and women aged 30-70 with systolic blood pressure 120-139 mm Hg, 7-day diets (n = 38) Evidence B source
  Plasma and salivary nitrate and nitrite at least fourfold higher; no difference in blood pressure or arterial stiffness
• Across 89 observational studies, the highest intake of cruciferous vegetables was linked to a 19% lower risk of digestive tract cancers than the lowest intake. — 81 articles covering 89 observational studies (n = 89 studies) Evidence C source
  RR 0.81 (95% CI 0.76-0.87), highest vs lowest intake

Safety, limits and interactions

• In a randomized trial of warfarin users, 9 of 13 patients (69%) who ate vitamin K-rich vegetables for 7 days rose above the target anticoagulation range. — patients on stable warfarin anticoagulation, 1 to 7 days of diet change (n = 37) Evidence B source
  7 days of vitamin K-rich vegetables (about 1,100 mcg vitamin K a day): 69% (95% CI 39-91%) out of range; vitamin K-poor vegetables: no change
• A systematic review of 2 dietary trials and 9 observational studies found conflicting evidence that dietary vitamin K upsets warfarin control, with effects seen mainly above about 150 mcg a day. — patients on vitamin K antagonists, studies to October 2015 (n = 11 studies) Evidence C source
  Possible effect on coagulation only above about 150 mcg vitamin K1 a day; restricting dietary vitamin K not a valid strategy
• A case report describes a woman on warfarin for a prosthetic heart valve who had a heart attack five weeks after starting a diet of lettuce, broccoli and turnip greens. — one 35-year-old woman with a prosthetic aortic valve on warfarin (n = 1) Evidence D source
  Myocardial infarction after 5 weeks of a high vitamin K vegetable diet

What people believe that the data does not support

• In a Quebec cohort of 317 warfarin users, 68% said they were told to limit or avoid vitamin K-rich foods, especially green vegetables. — 317 patients aged 36-97 starting warfarin in 2011-2012 (n = 317) Evidence C source
  68% advised to limit or avoid; 10% advised to keep intake stable

Who this works differently for

• Turnip greens are a regional staple in the US Lower Mississippi Delta that national food questionnaires did not list. — 842 white and 857 African American adults in the Lower Mississippi Delta (n = 1699) Evidence C source
  —

What is still unknown

• A systematic review of 18 lab studies found 129 phytochemicals in turnip greens, mostly glucosinolates, but how well people absorb them is not yet known. — 18 composition studies of turnip leaves, to April 2020 (n = 18 studies) Evidence D source
  129 phytochemicals: 19 glucosinolates, 33 breakdown products, 10 organic acids, 59 polyphenols

The bottom line

A cup of fresh turnip greens cooked without fat weighs 5.1 oz (145 g) in the US food survey. In a randomized crossover feasibility trial, 50 adults at raised colon cancer risk were given frozen greens, turnip greens among five kinds, and met the goal of one cooked cup a day on 73.2 percent of days. They ate some greens on 88.8 percent of days. Boiling greens in a little water and draining them keeps about 60 percent of vitamin C, 65 percent of folate and 95 percent of calcium and iron, by a 1975 USDA factor for the whole greens group. That table has no figure for vitamin K, so we cannot tell you how much of it survives the pot. We also found no study measuring how well people absorb the calcium or iron in turnip greens. Across 89 observational studies, people eating the most cruciferous vegetables had a lower rate of digestive tract cancers than those eating the least (RR 0.81, 95% CI 0.76 to 0.87). Turnip greens were not analyzed on their own, and an association of this kind does not show that the vegetables caused the difference. Lab work has catalogued 129 plant compounds in turnip greens, most of them glucosinolates and their breakdown products. The review that counted them says how people absorb and use them still has to be studied. The advice warfarin users get often runs the other way from that review. In a Quebec cohort of 317 people starting warfarin, 68 percent said they had been told to limit or avoid vitamin K-rich foods, especially green vegetables. Only 10 percent had been told to keep their intake steady. Who should be careful. If you take warfarin, the risk the trial measured was a sharp rise in vitamin K-rich vegetables over a few days. A 1984 case report describes a 35-year-old woman with an artificial heart valve on warfarin who had a heart attack five weeks after starting a diet of lettuce, broccoli and turnip greens to lose weight. One case says nothing about how often this happens. A change in how many greens you eat is a question for the person managing your warfarin. In the Lower Mississippi Delta turnip greens are a regional staple that national food questionnaires did not list.

Sources

1. tgrn-daily-r8-12 · food composition dataset
   Turnip greens, raw; vitamin K 251 ug; vitamin C 60 mg; vitamin A 579 ug RAE (per 100 g)
   USDA FoodData Central SR Legacy, Turnip greens, raw, FDC 170061 · checked 2026-10-01
2. tgrn-daily-r8-03 · randomized crossover trial
   During the intervention period, participants received a variety of frozen GLVs, including spinach, kale, collards, mustard greens, and turnip greens. ... During the intervention phase, participants consumed some GLVs on 88.8% of days and the adherence goal of 1 cooked cup/day was met on 73.2% of days.
   Nutrients, 2019 · checked 2026-10-01
3. tgrn-daily-r8-10 · food composition dataset
   Turnip greens, fresh, cooked, no added fat; 1 cup: 145 g; Quantity not specified: 73 g
   USDA FoodData Central survey (FNDDS) 2024-10-31, food code 72128211, fdc_id 2709634 · checked 2026-10-01
4. tgrn-daily-r8-11 · 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%
   USDA Table of Nutrient Retention Factors, Release 6 (2007), code 3004 · checked 2026-10-01
5. tgrn-daily-r8-02 · randomized crossover trial
   The effects of a 7-day high-nitrate diet intervention (increased nitrate intake by at least 300 mg/day from green leafy vegetables) were compared to a 7-day low-nitrate diet intervention. ... The high-nitrate diet intervention resulted in at least a fourfold increase in salivary and plasma nitrate and nitrite (P<0.001). Ambulatory, home, and office blood pressure and arterial stiffness were not different between the high-nitrate diet and the low-nitrate diet.
   Free Radic Biol Med, 2014 · checked 2026-10-01
6. tgrn-daily-r8-08 · 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].
   Crit Rev Food Sci Nutr, 2024 · checked 2026-10-01
7. tgrn-daily-r8-01 · randomized controlled 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. ... No changes were observed in the vitamin-K-poor group.
   J Intern Med, 1991 · checked 2026-10-01
8. tgrn-daily-r8-04 · 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. ... Median dietary intake of vitamin K1 ranged from 76 to 217 μg/day among studies, and an effect on coagulation may be detected only for high amount of vitamin intake (>150 μg/day). ... 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
9. tgrn-daily-r8-06 · case report
   A 35-year-old woman was receiving warfarin sodium therapy for a prosthetic aortic valve. She sustained a myocardial infarction five weeks after beginning a diet of lettuce, broccoli, and turnip greens to lose weight.
   Arch Intern Med, 1984 · checked 2026-10-01
10. tgrn-daily-r8-05 · cohort
    Most patients (68%) reported being advised to limit or avoid vitamin K-rich foods, particularly green vegetables, 10% reported being advised to aim for stable consumption of vitamin K-rich foods, and 22% did not recall receiving any vitamin K-related recommendation.
    J Acad Nutr Diet, 2016 · checked 2026-10-01
11. tgrn-daily-r8-09 · dietary survey
    Regional foods not on nationally used FFQs included grits, turnip greens, okra, ham hocks, chitterlings, crawfish, catfish, cracklings, jambalaya, potato logs, chicken and dumplings, and sweet potato pie.
    Public Health Nutr, 2005 · checked 2026-10-01
12. tgrn-daily-r8-07 · systematic review
    We found 129 phytochemicals (19 glucosinolates, 33 glucosinolate-breakdown products, 10 organic acids and 59 polyphenolic compounds) reported in Turnip greens. ... However, detailed investigation on the pure compounds derived from Turnip green, their bioavailability, transport and metabolism after consumption is further needed.
    PLoS One, 2021 · checked 2026-10-01