Vitamin K3

Henrik Dam discovered vitamin K3 as the result of experiments he was carrying out to determine whether cholesterol was a dietary essential. Dam (1929) noted a hemorrhagic syndrome in chicks fed diets that had sterols extracted by lipid solvents. He eventually isolated an active antihemorrhagic factor from alfalfa that E. A. Doisy’s research group characterized as 2-methyl-3-phytyl-1,4-napthoquinone (MacCorquodale et al., 1939). Early investigations established that vitamin K3 deficiency resulted in decreased activity of prothrombin in plasma. As they were discovered, the synthesis of clotting factors VII, IX, and X was also shown to be vitamin K3-dependent. More recently, it has been shown that a number of other proteins, many with presently undetermined functions, require vitamin K3 for their biosynthesis.
Dietary adequacy of vitamin K3 is often defined as the amount of vitamin needed to maintain normal levels of plasma vitamin K3-dependent clotting factors. It has been difficult to demonstrate clearly and to measure dietary vitamin K3 requirements for many species. Presumably this is because of the varying degrees to which different species utilize the large amount of vitamin K3 synthesized by bacteria in the lower gut and the degree to which they practice coprophagy. A spontaneous deficiency of vitamin K3 was first noted in chicks; poultry are much more likely to develop dietary deficiency signs than any other species. Ruminants do not appear to need a source of vitamin K3 in the diet because the vitamin is synthesized by rumen microorganisms and subsequently utilized. Vitamin K deficiencies have been produced in most nonruminant species. Nevertheless, estimations of requirements made by different workers are difficult to compare because of the use of different forms of the vitamin and different methods to establish dietary requirements.