In the news: Evidence Expanding for Vitamin K’s Role in Heart Health

Vitamin K Basics

There are two forms of fat-soluble vitamin K: K1 or phylloquinone, and vitamin K2, the menaquinones.

Our diet supplies Vitamin K1 through vegetables (green leafy ones especially), vegetable oils, and some fruits. Meat, dairy, and eggs contain low levels of K1 and modest amounts of vitamin K2. Fermented foods like natto (from fermented soybeans) have high levels of menaquinones, and fermented cheeses are a source as well. The bacteria in our GI tract also produce menaquinones, though it’s not clear how much is absorbed.

Vitamin K is needed for blood to clot, and by a bone-building protein. It’s also required by a protein (matrix GLA-protein) that may play a role in the prevention of vascular calcification – the depositing of calcium in the middle or inner lining of arteries. One hypothesis is that inadequate vitamin K affects the function of matrix GLA-protein leading to greater artery calcification.

Vitamin K for Heart Health? Evidence Growing

New research(1) has found that people eating a vitamin K rich diet have a lower risk – up to 34% lower – of cardiovascular disease related to atherosclerosis “(ASCVD),” a build-up of cholesterol plaque in the walls of arteries causing obstruction of blood flow.

Researchers from Denmark and Australia examined information from more than 50,000 participants in the Danish Diet Cancer and Health Study. After 21 years of follow-up, about 8,700 of these participants (ASCVD-free at the study’s start) were hospitalized due to atherosclerotic conditions affecting the heart or blood vessels.

Since several large population-health studies have linked higher intake of vitamin K to a lower risk for ASCVD, the investigators wanted to see whether dietary vitamin K was associated with ASCVD hospitalizations.

Overall, the study found that participants in the highest vitamin K1 intake bracket (median 192 micrograms daily) had a 21% lower risk of being hospitalized for any ASCVD-related condition vs. those in the lowest intake bracket (median 57 micrograms a day). For vitamin K2, the risk of ASCVD-related hospitalization was 14% lower for the highest vs. lowest intake level.

Specifically, a 14% lower risk of hospitalization due to ischemic heart disease was seen for those in the highest vs. lowest vitamin K1 intake.

Participants consuming the most vitamin K1 also had a 17% lower risk of hospitalization for stroke, and a 34% lower risk of hospitalization for peripheral artery disease.

How Might Vitamin K Influence Heart Health?

Many factors are involved in the development of ASCVD such as inflammation, the metabolic syndrome and arterial calcification. Vitamin K is thought to influence cardiovascular health in several ways including reducing inflammation and helping to block arterial calcification.

Vascular calcification is one risk factor for coronary heart disease because it reduces artery elasticity. Healthy, flexible arteries can expand and briefly store blood from each heartbeat to help move blood to all areas of the body.

Both K1 and K2 are needed for good health. Some, though not all studies suggest that consuming adequate levels of K2 may be particularly important for artery health. The authors of the present study point out that their database of vitamin K content of foods is very comprehensive for vitamin K1, while there is much less information available for vitamin K2 food content.

Note: If you take the blood-thinning medication Coumadin, be sure to inform your doctor before increasing vitamin K intake through foods or supplements. Maintaining consistent intakes of vitamin K is important for this drug to work properly.

References

1. Bellinge JW, et al. Vitamin K intake and Atherosclerotic Cardiovascular disease in the Danish Diet Cancer and Health Study. J Am Heart Assoc. Epub Aug. 7, 2021.