There are three types of vitamin K, differentiated by whether they are naturally occurring, made by the body or synthetically manufactured. The body is able to store fat-soluble vitamins in the liver or fat tissues and vitamin K, widely known for its role as a blood clotting agent, falls into this category. Some vitamin K is made by the body, so vitamin K deficiency is not common.
Vitamin K-1
Vitamin K-1 has two forms; phylloquinone, which occurs naturally in foods, and phytonadione, a synthetic version. Phylloquinone is found in green, leafy vegetables as well as okra, prunes and avocados. Some oils such as soybean, olive and canola oils also have small amounts. Free phylloquinone is readily absorbed in the human digestive tract and concentrates mostly in the liver. Phytonadione is used as a treatment for some bleeding conditions.
Vitamin K-2
Vitamin K-2, known as menaquinones or MKs, are found in the forms MK4 and MK7. MK4 is present in small amounts in some meats and dairy products. Bacteria in the human gut makes MK7, but this form of the vitamin is also present in some cheeses and the Japanese soy product, natto.
Vitamin K-3
Vitamin K-3, or menadione, is a synthetic product. Vitamin K-3 is used to treat adults but not infants because it can cause a condition known as hemolytic anemia, according to Lab Tests Online. It is available both alone and in combination with synthetic vitamin K-1 as supplemental tablets in some countries, although the FDA forbids the sale of vitamin K-3 as a human supplement in the United States. Some alternative medicine proponents believe it has anti-cancer properties, but this claim has not been validated by scientific research, reports the American Cancer Society.
How Much Do You Need?
The amount of vitamin K you need to ingest daily to maintain proper function differs for infants, children and adults. Infants zero to 6 months old need 2 mcg, girls ages 4 to 8 years need 55 mcg while boys in the same age range need 75 mcg. Men, ages 19 and over need 120 mcg per day and women need 90 mcg per day. With the high concentration of menaquinones in the intestines and the phylloquinone absorbed from foods, vitamin K deficiency does not usually occur unless there is an underlying medical condition. Supplemental vitamins K-1 and K-2 are available as tablets and capsules for those with a deficiency. You should only take vitamin K supplements on the advice of your doctor.
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