Vitamin K is an essential fat-soluble vitamin that is heavily involved in the blood clotting process. This role is reflected in its name -- the "K" is derived from the German word "koagulation." There are two forms of vitamin K: plants synthesize phylloquinone, or vitamin K1, while bacteria synthesize vitamin K2. Vitamin K1 is the principal dietary source. The Institute of Medicine's current recommended daily intake for male and female adults is 120 micrograms and 90 micrograms, respectively.
Green, Leafy Vegetables
Green, leafy vegetables are the greatest source of vitamin K. Kale tops the list of vitamin K foods -- cooked kale contains 1062 micrograms in one cup, which is about 10 times the daily required amount. One cup of cooked spinach contains 888.5 micrograms, while one cup of cooked broccoli provides 183 micrograms of vitamin K. Collard and turnip greens contain 529 to 1059 micrograms of vitamin K per cup, depending on preparation method. Ten sprigs of raw parsley offer 164 micrograms of vitamin K. Cooking the vegetables seems to enhance vitamin K availability.
Other Vegetables
Besides the green, leafy ones, other vegetables contain vitamin K. Cooked okra contains 88 micrograms per cup, while cooked celery provides 57 micrograms of vitamin K per cup. One cup of raw tomatoes offers 14.2 micrograms of vitamin K. One cup of raw, pealed cucumber contains 17.1 micrograms, and carrots provide 14.5 micrograms of vitamin K per cup.
Vegetable Oils
Soybean, cottonseed, canola and olive oils are other contributors of dietary vitamin K. One tablespoon of olive oil contains 8.1 micrograms of vitamin K, while soybean oil contains more than triple that amount at 25 micrograms per tablespoon. Canola oil offers 16.6 micrograms of vitamin K in one tablespoon. Hydrogenation of oils, which refers to the process of converting unsaturated fatty acids to saturated fatty acids, may negatively affect the absorption and effect of the vitamin.
Other Foods
Other foods contain small amounts of vitamin K. One cup of soy milk contains 7.4 micrograms of vitamin K, while one cup of oats contains an equivalent amount. Vitamin K is also found in liver and some dairy products. Beef liver contains 3.3 micrograms per 3 ounce, and yogurt has 0.5 micrograms per 8 oz. container. Vitamin K1 is also available in multivitamin and other supplements in doses that range from 10 to 12 micrograms per supplement.
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