[Vitamin K in the Norwegian diet and osteoporosis].
In search of vitamin K literature, interesting results were discovered. A summary is presented. The literature was found by using Medline. The level of vitamin K1 in the Norwegian diet was estimated from tables of food consumption and vitamin K1 per 100 g. Vitamin K is required for the carboxylation of the amino acid glutamic acid to gamma-carboxyglutamic acids on proteins, which is essential for the calcium binding capacity of Gla proteins (such as osteocalcin). These proteins are found in tissues such as bone, brain, pancreas and lungs, showing that Gla proteins have further important functions. Low intakes of the vitamin may be an important factor for osteoporosis and possibly also for atherosclerosis. The level of vitamin K1 in the Norwegian diet (purchase level) is estimated to be 60 micrograms K1/day before correction of waste. This level is lower than the recommended dietary allowance (1 microgram/kg body weight/day). There is a discussion in the literature of whether the allowances should be considerably higher (375 micrograms K1/day). Deep green vegetables and soybean oil are the best sources of vitamin K1, while cheese gives some K2. On the basis of this knowledge about the importance of vitamin K and osteoporosis, an intervention test should be done with respect to the high incidence of osteoporosis in Norway. Analysis of Norwegian foods for vitamin K1 and K2 is needed.