REDUCTION OF VITAMIN-K-2 CONCENTRATIONS IN HUMAN LIVER ASSOCIATED WITH THE USE OF BROAD-SPECTRUM ANTIMICROBIALS

It is unclear whether menaquinones produced by the intestinal microflo ra play any role in human nutrition. Reports of coagulopathy due to vi tamin K deficiency occurring in patients receiving broad spectrum anti biotics indirectly suggest that vitamin K-2 produced by the gut microf lora may be utilized by the host. We analyzed the vitamin K-1 (phylloq uinone) and vitamin K-2 (menaquinone) content in a convenience sample of 22 human post-mortem liver samples, including 9 individuals who had been receiving broad spectrum antimicrobials prior to death and 13 in dividuals who had been victims of sudden, unexpected deaths. There wer e no significant differences in the mean (+/-SEM) phylloquinone conten t between the 2 groups [21.9 (+/-15.5) vs. 16.0 (+/-19.3) pmol/g wet w eight (excluding those who had received supplemental vitamin K-1)] but there was a significant difference (p < 0.05) in the total menaquinon e (MK) content, 70.0 (+/-23.3) vs. 423.1 (+/-141) pmol/g between the 2 groups. These findings suggest an association between receipt of broa d spectrum antibiotics and a reduction in hepatic menaquinone concentr ation, lending support to the hypothesis that a reduction in the gut m icroflora responsible for their production leads to reduced hepatic st ores of this form of the vitamin.