Vitamin K is known for its role in blood clotting and bone strength, but recent research shows that it has additional benefits. A growing body of evidence suggests that this fat-soluble vitamin also helps prevent osteoporosis, protects against arterial calcification and improves memory in older adults. It can be found in foods, including kale, broccoli, green tea, and turnip and cabbage greens. It is also available as a dietary supplement.
The recommended adequate intake of Vitamin K is 90 micrograms (mcg) per day for women 19 and over and 120 mcg for men. Most people get enough Vitamin K from their diets. There have been no reports of dangerous levels of Vitamin K when consuming it through food and supplements at recommended doses.
Dietary sources of Vitamin K include a variety of vegetables and meats, including liver and pork. The vitamin is also present in some fermented dairy products, such as yogurt and some naturally ripened cheeses, as well as some soy products, such as miso and natto. It is also available as a supplement in the form of vitamin K1 and K2.
Both forms of this vitamin are soluble, meaning they can be dissolved in water. Vitamin K1 is usually used in multivitamins and as a standalone supplement in 5 mg tablets, while the fat-soluble K2 can be found in some over-the-counter coagulation factor replacement products. It is important to talk to your doctor before taking any dietary supplements, especially high-dose Vitamin K2, as they can interfere with certain medications and may be able to decrease the effectiveness of some anticoagulants or increase bleeding in other circumstances.
This is particularly important for individuals who are on blood thinners such as warfarin or other medications that affect the ability to clot, since high doses of this vitamin can have a negative impact. It is also important to talk with your physician if you are on anticonvulsants, such as phenytoin or dilantin, or any cholesterol-lowering medications, since Vitamin K1 and K2 support blood clotting and can counteract the effects of these drugs.
A recent study suggested that high doses of Vitamin K2 can be beneficial for osteoporosis, as it promotes calcium absorption and improves bone density. However, more research is needed to confirm this finding. Vitamin K is also thought to reduce the risk of hip fractures by reducing the tendency to bleed excessively after a fall. This is particularly important in elderly individuals, where low Vitamin K intake is associated with a higher risk of this condition. Several studies have shown that a single serving of green, leafy vegetables daily can reduce the risk of fracture by up to 50%. This is especially true for women, who have a higher rate of hip fractures. This is because the high amount of Vitamin K2 in these vegetables prevents calcification and weakening of the bones. This is a result of the fact that it helps to move calcium into the matrix, where it can be absorbed.