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 vitamin K influence the intestinal profile of K-vitamins in vitamin K-deficient rats, 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 different forms of vitamin K, and it was determined how these diets affected the vitamin K concentration at various sites of the instestine, serum, and the liver. It was found that the absorption of phylloquinone from standard food 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 colonic production of all higher menaquinones. High menaquinone-4 intake induces very high menaquinone-8 concentrations, both in the colonic contents as well as in the liver. These data suggest that menaquinone-4 may be converted into menaquinone-8 (but not into other menaquinones) via a metabolic pathway which has not been reported previously.
Koivu-Tikkanen
T J
TJ
Department of Applied Chemistry and Microbiology, Faculty of Agriculture and Forestry, University of Helsinki, Finland.
Schurgers
L J
LJ
Thijssen
H H
HH
Vermeer
C
C
D000042:Absorption; D000818:Animals; D005766:Gastrointestinal Contents / Q000737:chemistry; D007413:Intestinal Mucosa / Q000378:metabolism; D008099:Liver / Q000737:chemistry / Q000378:metabolism; D008297:Male; D051381:Rats; D011917:Rats, Inbred Lew; D014812:Vitamin K / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics; D014813:Vitamin K Deficiency / Q000188:drug therapy* / Q000378:metabolism
D014812:Vitamin K