Everyone knows the importance of taking Vitamin C to help strengthen the immune system and avoid scurvy, and that B complex vitamins help to combat stress, but other equally important vitamins are often overlooked. Vitamin K is one of these essential, but often ignored vitamins that perform many vital functions in the body.
History
This fat soluble vitamin was discovered in 1930 by Henrik Dam, a Danish scientist, while studying cholesterol-free diets in chickens. Dam had inadvertently removed Vitamin K from the chickens' diet, causing them to hemorrhage and bleed to death. The chickens did not recover when they received purified cholesterol in their diets, thus alerting Dam to the fact that there was a second substance that had been removed and was responsible for helping the blood to clot.
Function
Vitamin K is essential for blood clotting. It is necessary for bone growth and repair, and can help prevent osteoporosis by improving bone density. Deficiency of this important vitamin may lead to Alzheimer's disease. Vitamin K can help to stave off cardiovascular disease by prevent hardening of the arteries, and it has been shown to have anti-cancer effects. The September 2003 issue of the "International Journal of Oncology" published a study showing that lung cancer patients treated with Vitamin K exhibited slower cancer cell growth. Vitamin K deficiency may lead to poor blood sugar control and diabetes-like symptoms.
Types
There are three types of Vitamin K; two are natural, and one is synthetic. Vitamin K1, also called phylloquinone, is found in plants. Vitamin K2, known as menaquinone, is produced by the friendly bacteria that line the human digestive tract. A third type, vitamin K3, or menadione, is produced synthetically in a laboratory.
Considerations
The recommended intake of Vitamin K for adults ranges from 75 to 120 mcg. There is no toxicity associated with high intakes of the natural forms of Vitamin K, but the synthetic form, Vitamin K3, may be toxic in high doses. Vitamin K, like all fat-soluble vitamins, is stored in human fat tissue. Individuals with digestive disorders, such as Crohn's disease, colitis or celiac disease may need extra Vitamin K. Alcohol, antibiotics and aspirin can all lead to deficiencies of this vitamin, and those who suffer from heart disease or osteoporosis will benefit from higher levels of intake.
Sources
According to the United States Department of Agriculture, the foods highest in Vitamin K are kale, collards, spinach, turnip greens, mustard greens, Brussels sprouts, broccoli and onions. All leafy green vegetables contain high amounts of Vitamin K, as do blueberries, plums, black-eyed peas and lentils. Vitamin K is best absorbed when eaten with some amount of fat, such as butter or olive oil.
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