Vitamin K: the nutrient whose most useful fact is about a medicine

For most people vitamin K is a non-issue: deficiency is rare and the body needs little of it. For anyone taking warfarin it becomes one of the few nutrients where what you eat this week genuinely changes how a drug behaves.

What it does in the body

• Vitamin K is a coenzyme for vitamin K-dependent carboxylase, needed to make proteins involved in blood clotting and bone metabolism. — general adults Evidence E source

How much you need

• The Adequate Intake for vitamin K is 120 mcg a day for men and 90 mcg for women aged 19 and over. — general adults Evidence E source
• People eating more vitamin K had about 17 per cent fewer fractures, but the confidence interval touches no effect, and the benefit stops at around 120 micrograms a day. — adults in six cohort and case-control studies Evidence C source
• A single cup of raw spinach (25 grams, a small handful) carries the entire 120 µg daily reference intake for vitamin K on paper. — raw spinach, raw kale, cooked broccoli raab Evidence E source
• The British and American tables disagree about kale by 60%, and the British table has no vitamin K figure at all for baby spinach or boiled kale. — raw kale and raw spinach Evidence E source
• Vitamin K is the one nutrient here where the share of people falling short cannot be calculated at all. There is no requirement to fall short of. — US adults aged 19 and over Evidence E source

How well your body absorbs it

• Fed a large serving of kale with oil (the most favourable conditions there are), people absorbed under 5% of its vitamin K. — healthy adult volunteers, men and women, given a single 400 g serving of kale with 30 g of vegetable oil providing 156 nmol of phylloquinone Evidence B source
• Whether vitamin K is better absorbed from oil than from a vegetable depends on which measurement you use. The same experiment gives both answers. — younger adults aged 20-40 and older adults aged 60-80, men and women; diets provided 377 ± 46 µg/day from broccoli and 417 ± 45 µg/day from fortified oil Evidence B source
• Food tables are weaker on vitamin K2 than on K1: how much menaquinone foods contain is much less well known. — Western diets Evidence E source
• What cooking does to vitamin K cannot be answered from our data at all: the USDA retention table does not cover it. — all food groups and cooking methods in USDA Release 6 Evidence E source

What too little does

• Bleeding is the classic sign of vitamin K deficiency, and it appears only when the deficiency is severe. — people with severe vitamin K deficiency Evidence E source
• The classic sign of vitamin K deficiency, bleeding in newborns, has never been tested in a trial of vitamin K against no vitamin K in preterm infants. — preterm infants; the single eligible study enrolled infants under 32 weeks' gestation and compared three prophylactic regimens Evidence A source
• Giving vitamin K to pregnant women raised their own blood levels but did not reduce bleeding in their newborns. — healthy pregnant women at various gestational ages in six older trials from high-income countries, judged mostly at high or unclear risk of bias Evidence A source
• Nobody knows how much vitamin K the body actually needs, because the proteins it serves outside the liver have no agreed target. — general population; review of the vitamin K literature Evidence E source

Who is most likely to fall short

• People with conditions that stop them absorbing fat, such as cystic fibrosis, coeliac disease or ulcerative colitis, may not absorb vitamin K properly. — people with malabsorption disorders Evidence E source

What the evidence does and does not show

• The NIH says it is unclear whether vitamin K supplements in any form reduce the risk of osteoporosis. — people at risk of osteoporosis Evidence E source
• Across 14 randomised trials in 1,533 patients, vitamin K slowed the build-up of calcium in the coronary arteries. — patients with or at risk of vascular calcification, many on dialysis, 14 trials Evidence A source
• In the two-year RenaKvit trial, 360 micrograms of vitamin K2 a day did not protect the bones of 123 dialysis patients. — patients on chronic dialysis Evidence B source
• Vitamin K supplements looked like they cut clinical fractures by 28 per cent, but once the trials at high risk of bias were removed the effect stopped being significant. — adults, mainly post-menopausal or osteoporotic patients; 36 studies identified Evidence A source
• In prediabetes and type 2 diabetes, vitamin K lowered HbA1c by a full percentage point and fasting glucose modestly, but did not touch insulin itself. — adults with prediabetes or type 2 diabetes, mean age about 50 years; eight randomised trials Evidence A source
• In the longest trial yet, two years of 360 micrograms of MK-7 a day left coronary calcium scores lower than placebo in people with symptomatic coronary disease. — symptomatic patients with a coronary artery calcium score between 50 and 400 Agatston units at two hospitals in the Netherlands Evidence B source
• In dialysis patients, a year of high-dose vitamin K1 corrected the vitamin K biomarker almost completely and changed coronary calcification not at all. — haemodialysis patients with a coronary artery calcium score of 30 Agatston units or more Evidence B source
• The same 360 microgram dose of MK-7, given for six months to people with type 2 diabetes and heart disease, did nothing to arterial calcification and nothing to bone density. — patients with type 2 diabetes and a history of cardiovascular disease Evidence B source
• Pooling sixteen trials in postmenopausal women, vitamin K2 did not reduce fractures, and the result only turned positive after one study was removed from the analysis. — postmenopausal women Evidence A source
• For arterial stiffness in dialysis patients, MK-7 missed its primary outcome and only looked useful in the diabetic subgroup, which is the kind of result that needs its own trial. — chronic haemodialysis patients with arterial stiffness, defined as pulse wave velocity of 10 m/s or more Evidence B source
• The review that asked outright whether vitamin K for bones is myth or reality answered that the findings are conflicting and unclear. — observational and interventional studies in older men and women Evidence E source
• The 17% fewer fractures our own card reports is, in the 2026 pooling, a trend that does not reach significance. The confidence interval touches no effect. — adults in six prospective studies, with a dose-response analysis for non-linear relationships Evidence C source
• More was not better: in the same pooling the fracture benefit accumulated only up to about 120 micrograms a day, the reference intake itself. — adults in six prospective studies Evidence C source

What too much does

• No Tolerable Upper Intake Level was set for vitamin K, because of its low potential for toxicity. — general adults Evidence E source

Medicines it interacts with

• People taking warfarin and similar anticoagulants need a steady vitamin K intake, because sudden changes can increase or decrease the anticoagulant effect. — general adults Evidence E source
• People taking warfarin have to keep their vitamin K intake steady, because sudden changes make the drug work more or less than intended. — people taking warfarin and similar anticoagulants Evidence E source

What to do with this

If you are not on an anticoagulant, vitamin K asks nothing of you beyond eating greens from time to time. Kale, spinach, broccoli and other leaves carry far more than the daily requirement in a normal portion.

If you take warfarin or a similar drug, the rule is consistency rather than avoidance. Sudden changes in vitamin K intake, in either direction, change how well the drug works. A big salad after weeks without one is the kind of change that matters, and quietly cutting greens out is just as disruptive as adding them.

Deficiency is rare and mostly belongs to people who cannot absorb fat properly, such as those with cystic fibrosis, coeliac disease or short bowel syndrome.

Vitamin K2 is sold hard for bones and arteries, so it is worth knowing where the trials stand. In 123 dialysis patients given 360 micrograms a day for two years, bone density fell faster at the wrist and slower at the spine, and the authors concluded it does not preserve bone. On arteries, pooling 14 trials shows a slowing of coronary calcium that is statistically real and small, in patients who mostly had kidney disease. Neither finding supports buying K2 for a healthy skeleton.

On how much: fracture risk in the population data falls as vitamin K intake rises only up to about 120 micrograms a day and then stops falling, which is the same figure as the recommendation. Above that there is nothing to chase.

If you have type 2 diabetes or prediabetes, one thing is worth a mention at your next appointment. Pooling eight randomised trials, vitamin K lowered HbA1c by a full percentage point. That is a large enough move to matter to anyone whose doses are set by that number, and it is far too small a body of evidence to take vitamin K for.

New parents get the most uncomfortable finding on this page. A Cochrane review looked for a randomised trial of vitamin K against no vitamin K in preterm infants and found none, and six older trials of vitamin K given to mothers in pregnancy raised the mothers' levels without lowering bleeding in their babies. That is a gap in the evidence rather than an argument against the injection, and it is a conversation to have with the team looking after your baby.

A cup of spinach does cover the number, and that is not the same as covering you

Every vitamin K page, this one included, tells you that a handful of greens covers the day. The arithmetic is right. Raw spinach carries 482.9 micrograms per 100 g, so a cup of it, about 25 g, comes to 120.7 micrograms, which is the entire daily reference intake. Raw kale is 390 per 100 g, so a cup is 97.5 and a single leaf is 39.

Unsettled. Then somebody measured what people actually absorb. Fed a large serving of kale with oil, the most favourable condition there is, bioavailability of phylloquinone came out at 4.7 per cent. Under one twentieth. Plasma peaked between 6 and 10 hours at about 2.1 nmol/L and fell away quickly, with a half-life in plasma of 8.8 hours against 215 hours in tissue. So the cup of spinach is true as arithmetic and misleading as advice. What saves it is that nobody knows what you actually need, so there is no gap to worry about. It is still worth knowing that the reassuring sentence on every page about this vitamin is built on the number in the table rather than on the number in the person.

Unsettled. Oil is not a reliable fix either, and the same experiment gives both answers depending on which measurement you read. Comparing fortified oil against broccoli, the 24-hour area under the curve was clearly greater on the oil. The 24-hour fasting plasma phylloquinone showed no difference between them at all. One study, two defensible conclusions, which is why the advice to add fat to your greens is sensible and should not be sold as settled.

Why nobody can tell you whether you are short

Vitamin K works as a cofactor for carboxylating a family of proteins. The ones in the liver run blood clotting, and the amount needed for those is known, which is where 120 micrograms comes from. The ones outside the liver are involved in bone and in vascular calcification, and how much vitamin K they need for optimal function has never been established.

Unsettled. That gap shows up directly in the national survey. Median intake is 75.4 micrograms a day, 74.5 for men and 76.6 for women, while the mean is 120.4 and the 95th percentile is 364.2, which is an extremely lopsided distribution driven by whoever ate a salad that day. The shortfall table carries no row for vitamin K, because there is no requirement to fall short of. This is the one nutrient on the site where the share of people coming up short cannot be calculated at all.

The bone claim, at its current size

Unsettled. The observational fracture finding got pooled again in 2026 and came out as a trend rather than a result. Overall fractures ran at a risk ratio of 0.83 with a confidence interval from 0.68 to 1.01, which touches no effect. Hip fractures ran at 0.76 with an interval from 0.56 to 1.02, which also touches it. The direction has been consistent across a lot of work and the significance keeps not arriving, and those two facts belong in the same sentence.

Established. One detail inside that pooling is useful whatever you conclude about the rest. Fracture risk fell with vitamin K intake only up to about 120 micrograms a day, which is the reference intake itself, and the authors describe the association as U-shaped around that level. More was not better. That is an argument against the high-dose K2 products, made from the same data people use to sell them.

The review that asked the question head on, whether vitamin K for bones is myth or reality, answered that the findings are conflicting and unclear. The biology is genuinely attractive: vitamin K carboxylates osteocalcin, which regulates how bone takes up mineral, and it appears to help osteoblasts mature and to limit the cells that break bone down. Attractive biology with conflicting trials is the pattern this site keeps meeting, and vitamin E further up the same list is what it usually means.

Two gaps in our own data, said out loud

The food tables disagree about greens more than you would expect. The British table puts raw curly kale at 623 micrograms per 100 g and the American one puts raw kale at 390, a difference of about 60 per cent for the same vegetable. They swap places on spinach, 394 against 482.9. The British table carries no vitamin K figure at all for baby spinach or for boiled kale.

And what cooking does to vitamin K cannot be answered from our data. The USDA retention table covers sixteen nutrients and vitamin K is not one of them, so it appears neither among the nutrients mapped nor among those skipped. Anyone who tells you boiling destroys the vitamin K in kale is not reading it off that table, because the row does not exist.

Vitamin K2 is weaker still. It reaches the diet as at least ten different menaquinones that differ in chain length, made by bacteria apart from menaquinone-4, which the body forms from phylloquinone. How much of any of them foods contain is much less well known than the K1 figures, so a K2 number in a table deserves more doubt than a K1 number.

Where to get it from food

The bottom line

Men need 120 micrograms a day and women 90, and no upper limit was set because the vitamin has low potential for toxicity. Leafy greens carry most of it. Bleeding is the classic sign of deficiency and it appears only in severe cases, usually alongside a condition that blocks fat absorption. The warfarin rule is the practical heart of this page: intake has to stay steady, because sudden changes in vitamin K make the drug work more or less than intended. On bones the answer is now firm enough to give. A two-year trial in 123 dialysis patients found that 360 micrograms of K2 a day did not protect their bones. Pooling six randomised trials in postmenopausal women, fractures came out the same as placebo, and the result turned positive only after one study was taken out of the analysis. On arteries the picture splits. The longest trial, two years of MK-7 in people with symptomatic coronary disease, left calcium scores lower than placebo, and 14 pooled trials point the same way. Then six months of the same dose in type 2 diabetes did nothing at all. A year of high-dose K1 in dialysis patients cut the blood marker by 86 per cent and left the calcification untouched. Every one of those trials measured a scan rather than a heart attack. One more thing appears on no label. The classic reason vitamin K is given at all, bleeding in newborns, has never been compared against no treatment in a randomised trial in preterm infants. Giving the mother vitamin K in pregnancy did not reduce bleeding in her baby either. Two things about the numbers here need saying plainly. The 120 micrograms is an adequate intake rather than a measured requirement, because the proteins vitamin K serves outside the liver have no agreed target, and the national survey holds no shortfall row for vitamin K at all. There is no requirement to fall short of. And a cup of greens covering the day's figure is arithmetic rather than nutrition: fed a large serving of kale with oil, which is the most favourable condition anyone has tested, people absorbed under 5 per cent of its vitamin K.

Sources

1. vitk-01 · Position of an expert body · expert body statement
   Vitamin K functions as a coenzyme for vitamin K-dependent carboxylase, an enzyme required for the synthesis of proteins involved in hemostasis (blood clotting) and bone metabolism and other diverse physiological functions
   NIH Office of Dietary Supplements, VitaminK - Health Professional Fact Sheet · checked 2026-09-16 · extracted
2. vitk-02 · Position of an expert body · expert body statement
   19+ years: 120 mcg for males and 90 mcg for females (value from the source's table, not a sentence)
   NIH Office of Dietary Supplements, VitaminK - Health Professional Fact Sheet · checked 2026-09-16 · extracted
3. vitk-r3-02 · Observational data · dose-response meta-analysis of observational studies
   A total of six studies encompassing 93,776 participants and 1394 instances of fractures were analyzed. We found a trend towards a decreased risk of overall fractures with increased vitamin K consumption, with a risk ratio of 0.83 (95% CI, 0.68-1.01). Similarly, vitamin K intake showed a trend toward a reduced risk of hip fractures (risk ratio: 0.76, 95% CI: 0.56-1.02; I2 = 43.91%). Furthermore, the risk of overall fractures decreased with dietary vitamin K consumption up to 120 μg/day.
   Current Rheumatology Reviews, 2026 · checked 2026-09-17 · independently re-checked
4. vitk-a-06 · Position of an expert body · reference dataset
   Spinach, raw · Vitamin K (phylloquinone) 482.9 UG на 100 г [fdc_id 2709614] · 1 cup 25 г 120.7 UG · Guideline amount in salad 50 г 241.4 UG || Kale, raw · 390 UG на 100 г [fdc_id 2709599] · 1 cup 25 г 97.5 UG · 1 leaf 10 г 39.0 UG || Broccoli raab, cooked · 228.1 UG на 100 г [fdc_id 2709573] · 1 cup 170 г 387.8 UG
   USDA FNDDS 2021-2023; Adequate Intake from DRI, National Academies · checked 2026-09-21 · independently re-checked
5. vitk-a-07 · Position of an expert body · reference dataset
   CoFID 13-234 Curly kale, raw — Vitamin K1 (µg) 623.00 · CoFID 13-572 Spinach, mature, raw — Vitamin K1 (µg) 394.00 · CoFID 13-521 Spinach, baby, raw — Vitamin K1 порожньо · CoFID 13-649 Curly kale, boiled in unsalted water — Vitamin K1 порожньо · FNDDS 2709599 Kale, raw — 390 UG на 100 г · FNDDS 2709614 Spinach, raw — 482.9 UG на 100 г
   CoFID 2021 (Public Health England, OGL v3.0) and USDA FNDDS 2021-2023 · checked 2026-09-21 · independently re-checked
6. vitk-a-09 · Position of an expert body · national dietary survey
   vitamin_k_ug · усі 19+ n=4886 median 75.4 mean 120.42 p5 14.3 p95 364.2 · ч 19+ median 74.5 · ж 19+ median 76.6 · таблиця below: жодного рядка для vitamin_k_ug (для thiamin_mg, vitamin_b6_mg, zinc_mg і sodium_mg рядки є)
   NHANES 2021-2023 (DR1TOT/DEMO), weighted; Adequate Intake from DRI, National Academies · checked 2026-09-21 · independently re-checked
7. vitk-a-01 · Randomised controlled trial(s) · controlled isotopic absorption and kinetics trial
   Modelling results demonstrated a mean (n 6) bioavailability of phylloquinone from kale to be 4.7%. Plasma and tissue half-times for phylloquinone were found to be 8.8 and 215 h, respectively.
   British Journal of Nutrition, 2010 · checked 2026-09-21 · independently re-checked
8. vitk-a-02 · Randomised controlled trial(s) · controlled comparative absorption trial
   The mean AUC for plasma phylloquinone concentrations (both unadjusted and adjusted) were significantly greater after consumption of the phylloquinone-fortified oil diet compared with the broccoli diet (P < 0.001). However, there were no differences between the two treatments in 24-h fasting plasma phylloquinone concentrations.
   Journal of Nutrition, 2002 · checked 2026-09-21 · independently re-checked
9. vitk-a-05 · Position of an expert body · scoping review
   However, less is known about the content of menaquinones than phylloquinones in foods.
   Food & Nutrition Research, 2023 · checked 2026-09-21 · independently re-checked
10. vitk-a-08 · Position of an expert body · reference dataset
    nutrients_mapped: calcium_mg, choline_mg, copper_mg, folate_total_ug, iron_mg, magnesium_mg, niacin_mg, phosphorus_mg, potassium_mg, riboflavin_mg, sodium_mg, thiamin_mg, vitamin_b12_ug, vitamin_b6_mg, vitamin_c_mg, zinc_mg — вітаміну K немає ні тут, ні в nutrients_skipped
    USDA Table of Nutrient Retention Factors, Release 6 (2007), as processed into data/entities/retention.json · checked 2026-09-21 · independently re-checked
11. vitk-05 · Position of an expert body · expert body statement
    Bleeding and hemorrhage are the classic signs of vitamin K deficiency, although these effects occur only in severe cases.
    NIH Office of Dietary Supplements, Vitamin K - Health Professional Fact Sheet · checked 2026-09-16 · extracted
12. vitk-r3-03 · Meta-analysis or systematic review · Cochrane systematic review of randomised trials
    We did not identify any eligible studies that compared vitamin K to no treatment.One study compared intravenous (IV) to intramuscular (IM) administration of vitamin K and compared various dosages of vitamin K. Three different prophylactic regimes of vitamin K (0.5 mg IM, 0.2 mg vitamin K1, or 0.2 mg IV) were given to infants less than 32 weeks' gestation.
    Cochrane Database of Systematic Reviews, 2018 · checked 2026-09-17 · independently re-checked
13. vitk-r3-04 · Meta-analysis or systematic review · systematic review and meta-analysis of randomised trials
    We included older trials from high-income countries (six; 21,493 women-newborns), judged mostly as high or unclear bias risk...We meta-analysed neonatal bleeding (RR 1.16, 95% CI 0.59 to 2.29; P = 0.67) and maternal plasma VK1 (MD 2.46, 95% CI 0.98 to 3.93; P = 0.001).
    Scientific Reports, 2018 · checked 2026-09-17 · independently re-checked
14. vitk-a-04 · Position of an expert body · scoping review
    However, the amount of vitamin K needed for optimal functioning of the different VKDPs is not known.
    Food & Nutrition Research, 2023 · checked 2026-09-21 · independently re-checked
15. vitk-06 · Position of an expert body · expert body statement
    People with malabsorption syndromes and other gastrointestinal disorders, such as cystic fibrosis, celiac disease, ulcerative colitis, and short bowel syndrome, might not absorb vitamin K properly
    NIH Office of Dietary Supplements, Vitamin K - Health Professional Fact Sheet · checked 2026-09-16 · extracted
16. vitk-08 · Position of an expert body · expert body statement
    Although vitamin K is involved in the carboxylation of osteocalcin, it is unclear whether supplementation with any form of vitamin K reduces the risk of osteoporosis.
    NIH Office of Dietary Supplements, Vitamin K - Health Professional Fact Sheet · checked 2026-09-16 · extracted
17. vitk-t1 · Meta-analysis or systematic review · systematic review and meta-analysis
    Our analysis revealed that VK supplementation has a significant effect on CAC scores, slowing down the progression of CAC [I2 = 34%, MD= -17.37, 95% CI (-34.18, -0.56), p = 0.04].
    Zhang et al., Frontiers in Nutrition, 2023 · checked 2026-09-16 · independently re-checked
18. vitk-t2 · Randomised controlled trial(s) · randomised controlled trial
    In aggregate, our findings do not support MK-7 supplementation to preserve bone in patients on dialysis.
    Levy-Schousboe et al., Nephrology Dialysis Transplantation, 2023 · checked 2026-09-16 · independently re-checked
19. vitk-r3-01 · Meta-analysis or systematic review · systematic review and meta-analysis of randomised trials
    For post-menopausal or osteoporotic patients, meta-analysis showed that the odds of any clinical fracture were lower for vitamin K compared to controls (OR, 0.72, 95%CI 0.55 to 0.95). Restricting the analysis to low risk of bias trials reduced the OR to 0.76 (95%CI, 0.58 to 1.01). There was no difference in vertebral fractures between the groups (OR 0.96, 95%CI 0.83 to 1.11).
    Osteoporosis International, 2019 · checked 2026-09-17 · independently re-checked
20. vitk-r3-05 · Meta-analysis or systematic review · meta-analysis of randomised trials
    The evidence showed a significant reduction in FBG, SMD = -0.22 (-0.39 to -0.05), HbA1c, MD = -1.00%, 95% CI (-1.92 to -0.07), and HOMA-IR, MD = -0.63, 95% CI (-1.20 to -0.06). However, no effect was observed on insulin (SMD = -0.39, 95% CI: -0.91 to 0.13, p = 0.15) and HOMA-β (MD = 6.56, 95% CI (-3.89 to 17.01), p = 0.2184.
    Nutrients, 2026 · checked 2026-09-17 · independently re-checked
21. vitk-r5-1 · Randomised controlled trial(s) · randomised controlled trial
    In the placebo group, CAC scores increased from a median (IQR) of 145 (99-217) AU to 173 (119-297) AU after the first year and to 214 (148-344) AU after the second. In the active treatment group, these values were 135 (89-226), 150 (110-254) and 184 (122-298) AU, respectively. The difference between the groups was significant (P = .02), even after adjustment for covariates.
    Vossen et al., JAMA Cardiology, 2026 · checked 2026-09-17 · independently re-checked
22. vitk-r5-2 · Randomised controlled trial(s) · randomised controlled trial, pilot
    Patients randomized to phylloquinone for 12 months had significantly reduced levels of dephospho-uncarboxylated MGP (86% reduction) and increased levels of phylloquinone and Gla-osteocalcin to Glu-osteocalcin ratio compared with placebo. There was no difference in the absolute or relative progression of coronary artery calcification between groups.
    Holden et al., Nephrology Dialysis Transplantation, 2023 · checked 2026-09-17 · independently re-checked
23. vitk-r5-3 · Randomised controlled trial(s) · randomised controlled trial
    Six months vitamin K supplementation did not reduce arterial calcification progression (β [95% CI]: - 0.02 [- 0.10; 0.06] for the total arterial calcification mass) or slow BMD decline (β [95% CI]: - 2.06 [- 11.26; 7.30] Hounsfield units for all vertebrae) when compared to placebo.
    Bartstra et al., European Journal of Nutrition, 2021 · checked 2026-09-17 · independently re-checked
24. vitk-r5-4 · Meta-analysis or systematic review · meta-analysis of randomised controlled trials
    The overall effect test of the six RCTs showed no significant difference in fracture incidence between the two groups (RR=0.96, P=0.65). However, after excluding one heterogeneous study, the overall effect test showed a significant reduction in fracture incidence with VK2 (RR = 0.43, P = 0.01)...And the pooled analysis of adverse reactions showed no significant difference between the VK2 and control groups (RR = 1.03, 95%CI 0.87 to 1.21, P = 0.76).
    Ma et al., Frontiers in Public Health, 2022 · checked 2026-09-17 · independently re-checked
25. vitk-r5-5 · Randomised controlled trial(s) · randomised controlled trial
    There was no significant difference in the change in cPWV at 24 weeks between the MK-7 group and standard care [-6.0% (-20.2, 2.3) vs. -6.8% (-19.0, 7.3), p = 0.24]. However, we found that MK-7 significantly decreased cPWV in patients with diabetes [-10.0% (-15.9, -0.8) vs. 3.8% (-5.8, 11.6), p = 0.008].
    Naiyarakseree et al., Nutrients, 2023 · checked 2026-09-17 · independently re-checked
26. vitk-a-03 · Position of an expert body · systematic review
    Several observational and interventional studies have examined the relationship between vitamin K and bone metabolism, but findings are conflicting and unclear.
    Metabolism, 2017 · checked 2026-09-21 · independently re-checked
27. vitk-a-10 · Observational data · systematic review and dose-response meta-analysis of cohorts
    A total of six studies encompassing 93,776 participants and 1394 instances of fractures were analyzed. We found a trend towards a decreased risk of overall fractures with increased vitamin K consumption, with a risk ratio of 0.83 (95% CI, 0.68-1.01).
    Current Rheumatology Reviews, 2026 · checked 2026-09-21 · independently re-checked
28. vitk-a-11 · Observational data · systematic review and dose-response meta-analysis of cohorts
    Furthermore, the risk of overall fractures decreased with dietary vitamin K consumption up to 120 μg/day.
    Current Rheumatology Reviews, 2026 · checked 2026-09-21 · independently re-checked
29. vitk-03 · Position of an expert body · expert body statement
    The FNB did not establish ULs for vitamin K because of its low potential for toxicity
    NIH Office of Dietary Supplements, VitaminK - Health Professional Fact Sheet · checked 2026-09-16 · extracted
30. vitk-04 · Position of an expert body · expert body statement
    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
    NIH Office of Dietary Supplements, VitaminK - Health Professional Fact Sheet · checked 2026-09-16 · extracted
31. vitk-07 · Position of an expert body · expert body statement
    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
    NIH Office of Dietary Supplements, Vitamin K - Health Professional Fact Sheet · checked 2026-09-16 · extracted