“Vitamin K2 prevents heart attacks by keeping calcium out of arteries.”
Vitamin K2 supplements have not been shown to prevent heart attacks, and a two-year trial of K2 with vitamin D found no clear effect on artery calcium.
Vitamin K2 is not a proven way to protect your heart. Trials have found at most a small change in artery calcium scores, which is not the same as fewer heart attacks.
If you want to lower your heart attack risk, ask your clinician to check your blood pressure, cholesterol and blood sugar before spending money on K2.
Safety note: Vitamin K2 can weaken warfarin and similar blood thinners that work against vitamin K. In a study of healthy volunteers taking one of these drugs, as little as 10 micrograms a day of K2 (MK-7), less than the usual 45 microgram retail dose, lowered blood-thinning levels enough to matter in some people.
Talk to a healthcare professional if: you take warfarin or another blood thinner that works against vitamin K and are thinking of starting or stopping K2 or a vitamin D product that contains it.
Trials of vitamin K have found at most a small slowing of artery calcium scores, and no trial has shown fewer heart attacks from K2. Confidence is Limited because the trials are small and short, mostly measure calcium scores rather than heart attacks, and the heart-attack link comes from diet surveys.
Vitamin K2 supplements have not been shown to prevent heart attacks, and a two-year trial of K2 with vitamin D found no clear effect on artery calcium. A review of 14 trials found vitamin K slightly slowed the rise in coronary calcium scores, but those scores are a marker, not heart attacks.
A Danish trial gave older men K2 (720 micrograms) plus vitamin D or a placebo for two years. In 304 men without known heart disease, coronary calcium rose in both groups, with no clear difference (203 vs 254 units). Fewer heart attacks, artery-opening procedures and deaths in the supplement group (1.9% vs 6.7%) were a side finding that the authors said needs new studies to test. The 2023 review of 14 trials (1,533 people, several forms of vitamin K) found calcium scores rose about 17 units less with vitamin K. The idea that K2 protects the heart comes mainly from diet studies: in a Dutch study of 4,807 adults, people who ate the most K2 had a 57% lower relative risk of dying of heart disease than those who ate the least. A diet survey like that can show a link but cannot show that K2 caused it.
- Hasific S, Oevrehus KA, Lindholt JS, et al. Effects of vitamin K2 and D supplementation on coronary artery disease in men: a RCT. JACC: Advances. 2023;2(9):100643. DOI: 10.1016/j.jacadv.2023.100643. PMID: 38938724. PMCID: PMC11198368
- Li T, Wang Y, Tu WP. Vitamin K supplementation and vascular calcification: a systematic review and meta-analysis of randomized controlled trials. Frontiers in Nutrition. 2023;10:1115069. DOI: 10.3389/fnut.2023.1115069. PMID: 37252246. PMCID: PMC10218696
- Geleijnse JM, Vermeer C, Grobbee DE, Schurgers LJ, Knapen MH, van der Meer IM, Hofman A, Witteman JC. Dietary intake of menaquinone is associated with a reduced risk of coronary heart disease: the Rotterdam Study. Journal of Nutrition. 2004;134(11):3100-3105. DOI: 10.1093/jn/134.11.3100. PMID: 15514282
- Theuwissen E, Teunissen KJ, Spronk HM, et al. Effect of low-dose supplements of menaquinone-7 (vitamin K2) on the stability of oral anticoagulant treatment: dose-response relationship in healthy volunteers. Journal of Thrombosis and Haemostasis. 2013;11(6):1085-1092. DOI: 10.1111/jth.12203. PMID: 23530987