ABSTRACT
The lack of good analytical methodology and the relatively infrequent observation of insufficient intake of vitamin K within the population hampered the development of accurate databases relevant to the amount of vitamin K in foods or biological tissues until the mid-1980s. The chick is the species most susceptible to development of a vitamin K deficiency and is the species that has most often been used for vitamin K bioassays. Plant material contains vitamin K in the form of phylloquinone, but animal products and bacterial sources often contain an extensive mixture of various isoprenalogs of the menaquinone series. Hemorrhagic disease of the newborn is a vitamin K deficiency that has been largely eliminated by vitamin K administration at birth and phylloquinone supplementation of infant formulas. The status of research efforts to accurately establish daily intake of vitamin K within the population and to accurately measure the plasma concentration of vitamin K as one measure of vitamin K adequacy represents reasonable progress.
