VITAMIN K—ARE YOU GETTING ENOUGH?
I’ve heard that Vitamin K is vital to our health. But I didn’t know much about it, so began a bit of research. I found that vitamin K is important because of its involvement in blood clotting and production of proteins in bones. In addition, some research shows that too little vitamin K can also affect us older adults in cognitive function, heart health and mobility.
I’d like to share more information that I gained from a Harvard School of Public Health (The Nutrition Source), article, Vitamin K. Here are excerpts:
Vitamin K is a fat-soluble vitamin that comes in two forms. The main type is called phylloquinone [K1], found in green leafy vegetables like collard greens, kale, and spinach. The other type, menaquinones [K2], are found in some animal foods and fermented foods. Menaquinones can also be produced by bacteria in the human body.
Vitamin K is found throughout the body including the liver, brain, heart, pancreas, and bone. It is broken down very quickly and excreted in urine or stool. Because of this, it rarely reaches toxic levels in the body even with high intakes, as may sometimes occur with other fat-soluble vitamins.
Vitamin K and Health
Blood clots
Vitamin K helps to make four of the 13 proteins needed for blood clotting, which stops wounds from continuously bleeding so they can heal. People who are prescribed anticoagulants (also called blood thinners) to prevent blood clots from forming in the heart, lung, or legs are often informed about vitamin K. Because of its blood clotting action, vitamin K has the potential to counteract the effects of blood thinning medications. People on anticoagulant medication such as warfarin (Coumadin) may be advised to eat a consistent amount of vitamin K from food and supplements. People taking anticoagulant medication are usually provided information about foods containing vitamin K from their health care provider.
Bone health
Vitamin K is involved with the production of proteins in bone, including osteocalcin, which is needed to prevent the weakening of bones. Some studies have shown that higher vitamin K intakes are associated with a lower incidence of hip fractures and low bone density. A report from the Nurses’ Health Study suggests that women who get at least 110 mcg of vitamin K a day are 30% less likely to break a hip than women who get less than that. Among the nurses, eating a serving of lettuce or other green, leafy vegetable a day cut the risk of hip fracture in half when compared with eating one serving a week. Data from the Framingham Heart Study also showed an association between high vitamin K intake and reduced risk of hip fracture in men and women and increased bone mineral density in women.
Heart disease
A few studies have researched the role of vitamin K for heart health. Vitamin K is involved with the production of matrix Gla proteins (MGP), which help to prevent calcification or hardening of heart arteries, a contributor to heart disease.
Recommended Amounts & Food Sources
For adults, the daily recommended amount of vitamin K is 120 micrograms (mcg) daily for men and 90 mcg for women.
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- A cup a day should be adequate with one of these green leafy vegetables: collard and turnip greens, kale, spinach, broccoli, Brussel sprouts, asparagus, cabbage
Other Food Sources include:
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- Soybean and canola oil
- Salad dressings made with soybean or canola oil
- Fortified meal replacement shakes
- Natto (fermented soybeans)
- Smaller amounts in meat, cheese, eggs.
Signs of Deficiency
Vitamin K deficiency in adults is rare, but may occur in people taking medications that block vitamin K metabolism such as antibiotics, or in those with conditions that cause malabsorption of food and nutrients. The following are the most common signs of a deficiency.
- A longer time for blood to clot or a prolonged prothrombin time (as measured in a physician’s office)
- Bleeding
- Hemorrhaging
- Osteopenia or osteoporosis
Did You Know?
Antibiotic medicines may destroy vitamin-K-producing bacteria in the gut, thereby potentially decreasing vitamin K levels, especially if taking the medicine for more than a few weeks. People who have a poor appetite while using long-term antibiotics may be at greater risk for a deficiency, and may benefit from a vitamin K supplement.- Because vitamin K is fat-soluble, it is best to eat vitamin K foods with some fat to improve absorption. So, drizzle some olive oil or add diced avocado to your favorite leafy green salad!
