Vitamin K2 Benefits: What the Evidence Shows

Quick answer

Vitamin K2 benefits, in short: Vitamin K2 is a form of vitamin K that helps proteins involved in bone-building work properly [3]. Trials in postmenopausal women suggest a small benefit for bone density [2][3], and two trials point to slower artery stiffening or calcification [4][1], though what that means for health is not known. The biggest safety point: vitamin K affects warfarin, so people on that medicine must talk to their doctor first [5]. We rate the evidence C: encouraging in a few small-to-medium trials, but benefits are mixed and mostly in particular groups.

What is vitamin K2?

Vitamin K is a group of vitamins your body needs for blood clotting and wound healing, and the NHS notes there is also some evidence it may help keep bones healthy [6]. Dietary vitamin K is found mainly in green leafy vegetables [6]. Vitamin K2 (menaquinones) comes in several forms. The form most often sold as a supplement is MK-7, which is the one in the trials below.

The NHS says adults need roughly 1 microgram (µg, also written mcg) of vitamin K per kilogram of body weight each day, and that a varied diet should provide all you need [6]. In the US, the NIH Office of Dietary Supplements lists an Adequate Intake of 120 µg a day for men and 90 µg a day for women aged 19 and over [7]. The NIH also notes that most US diets supply enough, and that your gut bacteria make some menaquinones [7].

Vitamin K2 benefits: what might it help with?

Possible benefit	Rating	In plain words
Bone density in postmenopausal women	Promising	Slightly less bone-density loss at some sites; fracture results are inconsistent [2][3]
Fractures	Mixed	The main analysis of six trials found no difference [3]
Artery stiffness	Promising	Improved in healthy postmenopausal women over three years [4]
Coronary artery calcification	Early	One trial in people with heart disease; the clinical meaning is unknown [1]

Ratings describe how good the research is, not a promise that it will work for you.

What the research says

• Bone density, 3-year trial. In 244 healthy postmenopausal women, 180 micrograms of MK-7 a day for three years meant a smaller age-related decline in bone density at the lower spine and the neck of the thigh bone, but not at the total hip [2]. PubMed · DOI
• Bone, review of 16 trials (6,425 postmenopausal women). Vitamin K2 improved lower-spine bone density. Across six trials, fractures were not significantly different from control (it only reached significance after one very different study was removed). Side effects were similar to the control groups [3]. PubMed · DOI
• Artery stiffness, 3-year trial. The same 244 women took MK-7 (180 micrograms a day) or placebo. Measures of artery stiffness improved in the MK-7 group, most clearly in women who started with stiffer arteries [4]. PubMed · DOI
• Coronary calcification, 2-year trial (VitaK-CAC). In 180 people with heart symptoms and some calcium in their heart arteries, 360 micrograms a day of MK-7 meant calcification grew more slowly than on placebo. The authors say the clinical significance of this is still to be determined [1]. PubMed · DOI

The limits: the bone and artery results in healthy women come from the same group of 244 women, and bone density is a stand-in measure rather than a count of broken bones.

Amounts and how people take it

These are amounts used in studies, not recommendations.

• Study amounts: 180 micrograms of MK-7 a day for three years in the healthy-women trials [2][4], and 360 micrograms a day for two years in the heart trial [1].
• Form: MK-7 is the form used in these trials. Labels may also list MK-4, which has been studied separately and which we have not covered here.
• Timing: the sources we checked don’t give a firm rule.
• Official advice: the NHS says taking 1 mg (1,000 micrograms) or less of vitamin K supplements a day is unlikely to cause harm, with not enough evidence on higher doses [6], and the NIH has not set an upper limit because of its low potential for toxicity [7]. The study amounts above are well below 1 mg.

Side effects, interactions and who should check first

In the bone review, side effects were not significantly different from control groups [3], and the heart trial reported no significant adverse effects [1]. The NHS says there isn’t enough evidence to say what happens with high daily doses [6], while the NIH reports no adverse effects from vitamin K in food or supplements [7].

Who should check with a doctor or pharmacist first

Check with a doctor or pharmacist first if you:

• take warfarin. This is the key one. A review of the topic found that both dietary and supplement vitamin K can change how well warfarin controls your blood. The NIH says people on warfarin and similar anticoagulants need a consistent vitamin K intake from food and supplements, because sudden changes can raise or lower the effect of the medicine [7]. Don’t start vitamin K2 without telling the clinic that manages your warfarin [5].
• take any other blood-thinning medicine, or have a clotting condition. The NIH lists similar anticoagulants used in some countries, such as phenprocoumon and acenocoumarol [7].
• take certain other medicines. The NIH says long antibiotic courses, cholesterol-lowering bile acid sequestrants (such as cholestyramine) and the weight-loss drug orlistat can lower vitamin K levels, and orlistat combined with warfarin might increase blood-clotting time [7].
• have a heart, liver or bone condition that is being treated
• are pregnant or breastfeeding

Where to buy

Look for the active form and amount (MK-7, in micrograms per serving), a stated third-party testing certificate you can check, and work out the price per daily dose rather than comparing pack prices.

FAQ

What is vitamin K2?

Vitamin K is a group of vitamins your body needs for blood clotting and wound healing, found mainly in green leafy vegetables [6]. Vitamin K2 (menaquinones) comes in several forms, and the one most often sold as a supplement, and used in the trials below, is MK-7. It helps proteins involved in bone-building work properly [3].

Does vitamin K2 work?

Trials in postmenopausal women suggest a small benefit for bone density, but the main analysis of six trials found no difference in fractures [2][3]. Two trials point to slower artery stiffening or calcification [4][1], though what that means for health is not known. We rate the evidence C.

How much vitamin K2 per day?

Studies used 180 micrograms of MK-7 a day for three years in healthy women [2][4] and 360 micrograms a day for two years in a heart trial [1]. The NHS says 1 mg (1,000 micrograms) or less of vitamin K supplements a day is unlikely to cause harm [6]. These are study amounts, not recommendations.

Who should not take vitamin K2?

Check with a doctor or pharmacist first if you take warfarin or another blood thinner, have a clotting condition, take long antibiotic courses, bile acid sequestrants or orlistat [5][7], have a treated heart, liver or bone condition, or are pregnant or breastfeeding. Don’t start vitamin K2 without telling the clinic that manages your warfarin [5].

Can you take vitamin K2 with Eliquis?

We found no information on vitamin K2 with Eliquis (apixaban) in our sources. The clear concern is warfarin: both dietary and supplement vitamin K can change how well it controls your blood [5], and NIH says people on warfarin and similar anticoagulants need a consistent vitamin K intake [7]. Ask the clinic or a pharmacist before starting.

Related pages

• Vitamin D
• Magnesium
• Omega-3
• Longevity supplements for beginners: where this fits in a beginner’s routine
• All supplements A-Z

Talk to your doctor

This page is for general information and is not medical advice. Speak to a doctor or pharmacist before starting any supplement, especially if you are pregnant or breastfeeding, take any medicine, or have a health condition.

References

We cite only studies and official pages we checked against PubMed, the publisher or the agency’s own site. The A to E evidence grades are explained in our editorial policy. See also our medical disclaimer and affiliate disclosure.

1. Vossen LM, de Leeuw PW, Schurgers LJ, et al. Two Years of Menaquinone-7 Supplementation and Coronary Artery Calcification: A Randomized Clinical Trial. JAMA Cardiol. 2026. PubMed · DOI
2. Knapen MH, Drummen NE, Smit E, et al. Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal women. Osteoporos Int. 2013. PubMed · DOI
3. Ma ML, Ma ZJ, He YL, et al. Efficacy of vitamin K2 in the prevention and treatment of postmenopausal osteoporosis: A systematic review and meta-analysis of randomized controlled trials. Front Public Health. 2022. PubMed · DOI
4. Knapen MH, Braam LA, Drummen NE, et al. Menaquinone-7 supplementation improves arterial stiffness in healthy postmenopausal women. A double-blind randomised clinical trial. Thromb Haemost. 2015. PubMed · DOI
5. Lurie Y, Loebstein R, Kurnik D, et al. Warfarin and vitamin K intake in the era of pharmacogenetics. Br J Clin Pharmacol. 2010. PubMed · DOI
6. NHS. Vitamins and minerals: vitamin K. nhs.uk (accessed 1 November 2026)
7. National Institutes of Health, Office of Dietary Supplements. Vitamin K: health professional fact sheet (updated 22 October 2026). ods.od.nih.gov (accessed 1 November 2026)