Intestinal, hepatic, and circulating vitamin K levels at low and high intakes of vitamin K in rats

The aim of the present study was to assess how high doses of dietary vitami n K influence the intestinal profile of K-vitamins in vitamin K-deficient r ats, and whether the induced changes are reflected in the hepatic vitamin K store. Vitamin K-deficient rats were fed for 10 d on diets containing diff erent forms of vitamin K, and it was determined how these diets affected th e vitamin K concentration at various sites of the instestine, serum, and th e liver. It was found that the absorption of phylloquinone from standard fo od is not more than 10 %, while the absorption of pharmacological doses of oil-solubilized phylloquinone and menaquinone-4 was also far from complete (18 and 55 % respectively). High intakes of phylloquinone suppress the colo nic production of all higher menaquinones. High menaquinone-4 intake induce s very high menaquinone-8 concentrations, both in the colonic contents as w ell as in the liver. These data suggest that menaquinone-4 may be converted into menaquinone-8 (but not into other menaquinones) via a metabolic pathw ay which has not been reported previously.