Vitamin K is classified as a fat-soluble vitamin and is stored in the liver and in fat tissue. Vitamin K is necessary in the body primarily for the clotting process, and gets the "K" in its name from the German word for coagulation -- koagulation. Vitamin K is also tied to bone health and contributes to strong, dense bone.
Recommended Intake
The University of Maryland Medical Center notes that vitamin K deficiencies are rare, in part because bacteria in the human intestines can synthesize the vitamin. Excessive use of antibiotics that kill these bacteria may lead to mild deficiencies, however. Deficiencies can lead to improper coagulation, or hemorrhaging, as well as weak bones. The Institute of Medicine's Food and Nutrition Board recommends a daily intake of just 90 mcg for adult women and 120 mcg for adult men of the vitamin.
Dietary Sources
Rich dietary sources of vitamin K include green, leafy vegetables such as kale, spinach, broccoli, cabbage, asparagus and dark green lettuce. Additional sources of the vitamin include beef liver and green tea. Eat more servings of greens each day to ensure you get adequate vitamin K; add greens as sandwich garnishes, and steam a side of broccoli or cabbage for a quick dinner side dish.
Supplements
Vitamin K exists as three types -- K1, or phylloquinone; K2, or manquinone; and K3, known as menaphthone or menadione. A synthetic form of K1 and K3 are generally found in multivitamins containing vitamin K. K1 and K3 are also available as a separate supplement, sold in 5 mg tablets. You can also buy water-soluble capsules of chloropyll to meet your vitamin K needs. These capsules are the most common over-the-counter form of vitamin K available. As with any new supplement, consult your doctor before adding synthetic vitamin K to your diet.
Cautions
If you take vitamin K as directed and do not exceed the recommended intake of the vitamin, you are unlikely to experience any negative side effects. Because vitamin K is excreted in breast milk, however, the University of Maryland Medical Center recommends that pregnant and breastfeeding women talk with their doctor before adding a vitamin K supplement. Individuals with the metabolic disorder glucose-6-phosphate dehydrogenase deficiency should also avoid vitamin K.
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