Vitamin K is a fat-soluble vitamin that is needed to build and maintain strong bones. Vitamin K is necessary for osteoblasts (bone building cells) to activate osteocalcin, a protein that binds calcium to bones. It may also inhibit the production of osteoblasts, the cells responsible for breaking down bone. Vitamin K is also involved in blood clotting. It is easy for most healthy individuals to consume the recommended amount of Vitamin K by eating a nutrient-rich diet.
The recommended daily intake for vitamin K
The adequate intake (AI) for vitamin K is 120 µg per day for men and 90 µg per day for women.
Typical intakes for vitamin K
Vitamin K deficiency is very rare and occurs when there is an inability to absorb the vitamin in the intestine. For example, vitamin K deficiency can occur after prolonged treatment with antibiotics when the bacteria in the intestinal tract is disturbed. Individuals with vitamin K deficiency usually have an increased tendency to bruise or bleed.
Foods containing vitamin K
Dietary sources of vitamin K include certain dark green leafy vegetables (such as kale, collard greens, spinach, mustard greens, turnip greens and brussel sprouts) and certain vegetable oils (soybean, canola, cottonseed, and olive). One cup of cooked kale contains more than 1000 µg of vitamin K. One cup of cooked broccoli contains about 300 µg of Vitamin K.
Vitamin K and bone health
Low vitamin K intakes appear to be associated with an increased risk of hip fractures among older men and women. However, it is not certain whether the increase in fracture rate is entirely due to low vitamin K intake. In some studies, higher dietary vitamin K intakes were also associated with higher consumption of green, leafy vegetables. There may be other characteristics of a diet higher in fruits and vegetables that could be responsible for lower fracture risk. Perhaps it is the other vitamins and/or minerals present in fruits and vegetables or the effect of fruits and vegetables on acid-base balance that works to lower fracture risk. Future research is needed to clearly understand the relationship of vitamin K to bone health.
What should I do to make sure that I get enough vitamin K?
Getting enough vitamin K in your diet may help promote strong bones. The best way to get the daily recommendation of vitamin K is to eat a nutrient-rich diet that contains a variety of foods with special emphasis on eating green leafy vegetables. For strong bones and a healthy heart, it is wise to use unhydrogenated vegetable oils (that are high in vitamin K), in moderation, as part of your fat intake.
Are there any special considerations about vitamin K?
It is important for people taking blood-thinning medications to know that vitamin K supplements or food containing vitamin K may reduce the effectiveness of their medication. Always follow the advice of your doctor or healthcare provider