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Dear Dietitian – What is vitamin K’s role in health?

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PICT Leanne McCrate Dear Dietitian
Leanne McCrate, RDN, CNSC

Dear Readers: An old vitamin is getting rave reviews lately. Most of you have heard of vitamin K, but did you know it is found in the diet in two forms? Vitamin K1, the most common form, was discovered by Danish scientist Henrik Dam in 1929 as he was studying cholesterol metabolism. It was known as the Koagulations vitamin for its distinct role in blood coagulation. The vitamin was spelled with a K because its discovery was first published in a German medical journal.

Vitamin K2 is another form of the nutrient. Your body can convert K1 to K2, but the process is inefficient. K2 is found in fermented foods like sauerkraut and natto, egg yolks, butter, Muenster cheese, and pork sausage.

K2 is rising in the ranks for its potential role in bone strengthening and heart health. Osteoporosis is a common disorder, especially in women over the age of 65. Osteoporosis occurs when there is a lack of calcium in the diet. In this case, the body will remove calcium from the bones to perform other tasks in the body. As a result, the bones become porous, weak, and more susceptible to fractures. It is believed that K2 activates osteocalcin, a protein that binds to calcium, so that it can be added to bones and make them stronger.

We need at least three servings of calcium-rich food every day. Sources include milk, plain yogurt, spinach, and kale, to name a few.  It is always best to get vitamins and minerals in your food rather than supplements, but sometimes life is busy, and our diets aren’t perfect. That’s when many people turn to calcium pills.

Recent studies have linked excess calcium supplementation to plaque buildup in the arteries, contributing to atherosclerosis, or hardening of the arteries, and heart disease. Interestingly, the same link is not found with calcium-containing foods or milk.

The National Institutes of Health (NIH) studied the impact of calcium supplementation on heart disease. The study consisted of over 388,000 people whose health was tracked for twelve years. They found that men, but not women, who took 1000 mg of calcium in pill form, with or without adding vitamin D, had a 20% higher risk of dying from a heart attack or stroke than those who did not take calcium supplements. This study was observational, which does not show cause and effect. Other studies have had similar findings in both men and women who supplement calcium (1).

The topic of calcium supplements and heart disease is controversial, as studies are mixed. An analysis of 31 separate studies on the effect of calcium supplements on heart disease found no link between the two. Other randomized, controlled trials (the gold standard of research) have also found no cause for concern (2).

K2 may keep arteries healthy by activating a protein that inhibits the buildup of calcium in the arterial walls. Thus, K2 may play a vital role in calcium-associated heart disease.

There are people who should not take vitamin K supplements. If you take Coumadin® (warfarin), DO NOT supplement Vitamin K, as it will interfere with blood clotting and increase the risk of a heart attack or stroke. Talk to your doctor if you have more questions about Vitamin K.

Until next time, be healthy!

Dear Dietitian


  1. Katarzynaa Maresz, Proper calcium use: vitamin K2 as a promoter of bone and cardiovascular health. Integr Med (Encinitas). 2015 Feb: 14 (1): 34-39. PMCID: PMC4566462, PMID 26770129
  2. Calcium and heart disease: what is the connection? 2017 January. Retrieved from

Leanne McCrate, RDN, CNSC, is an award-winning dietitian based in Missouri. Her mission is to educate consumers on sound, scientifically-based nutrition. Do you have a nutrition question? Email her today at Dear Dietitian does not endorse any products, health programs, or diet plans.