Vitamin K - It's Not Just Important For Clotting

Vitamin K was named for its role in coagulation (koagulation in German), but it turns out this important vitamin has significant roles beyond blood clotting. Work by Tufts researchers and others shows that vitamin K may be an important factor in bone health, cardiovascular health, and type 2 diabetes.

𝗩𝗜𝗧𝗔𝗠𝗜𝗡 𝗞𝟭 𝗩𝗘𝗥𝗦𝗨𝗦 𝗞𝟮

The originally-identified form of vitamin K is vitamin K1. “There are actually 11 forms of vitamin K,” says Sarah L. Booth, PhD, a professor at the Friedman School of Nutrition Science and Policy and director of the Jean Mayer USDA Human Nutrition Research Center on Aging (HNRCA). “Vitamin K1 is found in plants. The other 10 forms of vitamin K are collectively known as vitamin K2. One form of vitamin K2 is made in our bodies from vitamin K1. The other nine forms are produced by bacteria, either in the human gut or in foods fermented with the use of bacteria, including cheese, yogurt, and other fermented dairy products.” Our gut bacteria and fermented foods, therefore, may play an important role in what forms of vitamin K we have in our bodies.

𝗧𝗛𝗘 𝗖𝗔𝗟𝗖𝗜𝗨𝗠 & 𝗩𝗜𝗧𝗔𝗠𝗜𝗡 𝗞 𝗖𝗢𝗡𝗡𝗘𝗖𝗧𝗜𝗢𝗡

Vitamin K appears to play a critical role in the regulation of calcium in our bodies. “There are certain proteins responsible for keeping calcium away from places we don’t want calcium—like our joints and our arteries—and these proteins cannot function without vitamin K,” says Booth. Low vitamin K status, therefore, could potentially increase risk for build-up of calcium in the artery walls (hardening of the arteries) and the calcification of joint tissue that leads to osteoarthritis. “Adequate intake of dietary vitamin K cannot reverse hardening of the arteries, for example, but it is associated with lower risk of the calcification spreading,” says Booth.

Kyla Shea, PhD, a scientist in the vitamin K lab at the HNRCA, has been studying vitamin K and osteoarthritis. “In observational studies we and others have found better vitamin K status to be associated with less osteoarthritis and better lower-extremity function and mobility,” says Shea, “but we will need clinical trials to know for sure if vitamin K can reduce osteoarthritis development or progression.” Since osteoarthritis is the leading cause of lower extremity disability in older adults, and this age group is also more likely to have lower vitamin K intakes, Shea points out it is particularly important for older adults to be aware of this possible connection.

There may also be a connection between vitamin K and bone health. “Multiple proteins in bone require vitamin K,” says Booth, “and some data suggest a fairly strong association between blood markers of vitamin K intake and bone mineral density in older adults. But multiple randomized controlled trials that gave people either vitamin K1 supplements or a placebo found no benefit of K1 supplementation for bone health.”

𝗩𝗜𝗧𝗔𝗠𝗜𝗡 𝗞𝟮 𝗔𝗡𝗗 𝗗𝗜𝗔𝗕𝗘𝗧𝗘𝗦

According to Dariush Mozaffarian, MD, DrPH, dean of the Friedman School of Nutrition Science and Policy and editor-in-chief of Tufts Health & Nutrition Letter, a growing body of research suggests that vitamin K2 may also protect against type 2 diabetes. “In small controlled trials, vitamin K2 supplements have improved insulin sensitivity and glucose handling,” says Mozaffarian, “perhaps through effects on metabolism of osteocalcin, an important hormone. Vitamin K2 may also reduce inflammation by inactivating key pro-inflammatory pathways. In long-term observational studies, foods rich in vitamin K2, such as cheese, are also linked to lower risk of type 2 diabetes.” This emerging research suggests that vitamin K2 may help prevent type 2 diabetes. “This potential effect is not yet widely recognized, and I believe future research will focus on vitamin K2 levels in cheese and other fermented foods and their possible benefits for type 2 diabetes,” says Mozaffarian.

𝗪𝗛𝗔𝗧 𝗙𝗢𝗢𝗗𝗦 𝗣𝗥𝗢𝗩𝗜𝗗𝗘 𝗩𝗜𝗧𝗔𝗠𝗜𝗡 𝗞?

Vitamin K is found naturally in many foods. You can get recommended amounts of vitamin K by eating a variety of foods, including the following:

• Green leafy vegetables, such as spinach, kale, broccoli, and lettuce
• Vegetable oils
• Some fruits, such as blueberries and figs
• Meat, cheese, eggs, and soybeans

𝗪𝗛𝗔𝗧 𝗞𝗜𝗡𝗗𝗦 𝗢𝗙 𝗩𝗜𝗧𝗔𝗠𝗜𝗡 𝗞 𝗗𝗜𝗘𝗧𝗔𝗥𝗬 𝗦𝗨𝗣𝗣𝗟𝗘𝗠𝗘𝗡𝗧𝗦 𝗔𝗥𝗘 𝗔𝗩𝗔𝗜𝗟𝗔𝗕𝗟𝗘?

Vitamin K is found in multivitamin/multimineral supplements. Vitamin K is also available in supplements of vitamin K alone or of vitamin K with a few other nutrients such as calcium, magnesium, and/or vitamin D. Common forms of vitamin K in dietary supplements are phylloquinone and phytonadione (also called vitamin K1), menaquinone-4, and menaquinone-7 (also called vitamin K2).

𝗔𝗠 𝗜 𝗚𝗘𝗧𝗧𝗜𝗡𝗚 𝗘𝗡𝗢𝗨𝗚𝗛 𝗩𝗜𝗧𝗔𝗠𝗜𝗡 𝗞?

Vitamin K deficiency is very rare. Most people in the United States get enough vitamin K from the foods they eat. Also, bacteria in the colon make some vitamin K that the body can absorb. However, certain groups of people may have trouble getting enough vitamin K:

• Newborns who don’t receive an injection of vitamin K at birth
• People with conditions (such as cystic fibrosis, celiac disease, ulcerative colitis, and short bowel syndrome) that decrease the amount of vitamin K their body absorbs
• People who have had bariatric (weight loss) surgery

𝗪𝗛𝗔𝗧 𝗛𝗔𝗣𝗣𝗘𝗡𝗦 𝗜𝗙 𝗜 𝗗𝗢𝗡’𝗧 𝗚𝗘𝗧 𝗘𝗡𝗢𝗨𝗚𝗛 𝗩𝗜𝗧𝗔𝗠𝗜𝗡 𝗞?

Severe vitamin K deficiency can cause bruising and bleeding problems because the blood will take longer to clot. Vitamin K deficiency might reduce bone strength and increase the risk of getting osteoporosis because the body needs vitamin K for healthy bones.

𝗛𝗘𝗔𝗟𝗧𝗛 𝗡𝗢𝗧𝗘

Before adding a Vitamin K supplement to your daily routine, consult with your doctor. Odds are you probably don’t need a vitamin K supplement if you’re eating a well balanced diet and are not one of the higher risk people listed above.