Belonging to the fat-soluble family of vitamins, vitamin K is necessary for blood clotting and bone health, so deficiencies in this vitamin have the potential to cause uncontrolled bleeding and weak bones. Most vitamin K is obtained from food sources such as green, leafy vegetables and dairy products. Although supplementing vitamin K with your diet might be beneficial, taking too much can be toxic.
Role of Vitamin K
Helping form prothrombin, the protein responsible for blood clotting, vitamin K plays a significant role in the prevention of excess bleeding. Vitamin K also increases bone density and reduces the risk of developing osteoporosis. According to Sareen Gropper, author of "Advanced Nutrition and Human Metabolism," higher vitamin K levels are found in people with greater bone density, while lower levels correspond to those with osteoporosis.
Recommended Daily Amount for Vitamin K
The recommended dietary allowance, or RDA, for vitamin K is 80 micrograms per day for men and 65 micrograms per day for women. Five micrograms per day is recommended for infants. Adequate amounts of vitamin K can be obtained by regularly following a diet rich in leafy green vegetables. However, adults between the ages of 18 and 45 might experience increased health benefits from taking a 50 to 100 mg supplement dose of vitamin K.
Sources of Vitamin K
Dark green, leafy vegetables, such as broccoli, kale, spinach and brussels sprouts, contain an abundance of vitamin K. In regard to animal foods, liver is a rich source of vitamin K. Milk, eggs and other dairy products also contain significant amounts of vitamin K, albeit a smaller amount than vegetables. Vitamin K is also produced by the bacteria growing inside your digestive tract, however, it is not known how much of this is used by the body, says Frances Sizer, author of "Nutrition: Concepts and Controversies."
Vitamin K Toxicity
When taken at doses exceeding 2,000 mcg per day, vitamin K supplements can be toxic and cause serious side effects. Pregnant women and children are most vulnerable to vitamin K poisoning, which involves damaging of the red blood cells and yellowing of the skin. Brain damage has also been associated with toxic levels of vitamin K. Due to these potentially fatal effects, vitamin K is only available as a prescription drug.
References
- "Advanced Nutrition and Human Metabolism"; Sareen Gropper; 2008
- "Nutrition: Concepts and Controversies"; Frances Sizer; 2007
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