Vitamin K, also called Menadione, is an essential fat-soluble vitamin that is required for the regulation of normal blood clotting functions. Dietary vitamin K is found primarily in the form of dark leafy vegetables, but most of our needs for this micronutrient are met by microorganisms that synthesize vitamin k in our intestinal tract. Vitamin K’s main function is in the synthesize of prothrombin, a protein vital for blood clotting. Vitamin K also aids in converting glucose into glycogen for storage in the liver, and may also play a role in forming bone formation and preventing osteoporosis. Cancer researchers are also looking into vitamin K’s potential to inhibit development of cancers of the breast, ovary, kidney, colon, stomach, bladder, and liver.
Vitamin K deficiency is rare except in the case of newborn infants. Most vitamin K is synthesized by microorganisms in our intestines. It can take several weeks for this bacteria to get established in newborns, so injections are generally given to the newborns immediately after birth. Vitamin K is often included in prenatal supplements for expecting mothers.
Vitamin K deficiency, though relatively uncommon in adults, can result in impaired blood clotting and internal bleeding. A deficiency of vitamin K can be caused by chronic use of antibiotics which can inhibit the growth of the intestinal microorganisms required for the synthesis of vitamin K. Serious liver disorders can also inhibit vitamin K’s function in the production of prothrombin, and any condition or syndrome that inhibits the digestion and absorption of fats in the intestines can also lead to deficiency symptoms.
The 1989 RDAs for vitamin K is 5 micrograms for newborn babies, and between 65 and 80 micrograms for adults. Vitamin K supplements are only available by prescription due to the danger of toxicity. Foods high in natural Vitamin K include alfalfa, broccoli, dark green leafy vegetables, and soybeans, blackstrap molasses, egg yolks, oats, liver, cheese, and wheat.