|ELLIS, JESSICA - Jean Mayer Human Nutrition Research Center On Aging At Tufts University
|KARL, J PHILIP - Us Army Research Institute Of Environmental Medicine
|OLIVERIO, ANGELA - University Of Colorado
|FU, XUEYAN - Jean Mayer Human Nutrition Research Center On Aging At Tufts University
|SOARES, JASON - The Us Army Combat Capabilities Development Command Soldier Center
|WOLFE, BENJAMIN - Tufts University
|HERNANDEZ, CHRISTOPHER - Cornell University
|MASON, JOEL - Jean Mayer Human Nutrition Research Center On Aging At Tufts University
|BOOTH, SARAH - Jean Mayer Human Nutrition Research Center On Aging At Tufts University
Submitted to: Gut Microbes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2021
Publication Date: 3/2/2021
Citation: Ellis, J.L., Karl, J., Oliverio, A.M., Fu, X., Soares, J.W., Wolfe, B.E., Hernandez, C.J., Mason, J.L., Booth, S.L. 2021. Dietary vitamin K is remodeled by gut microbiota and influences community composition. Gut Microbes. 13(1):1-16. https://doi.org/10.1080/19490976.2021.1887721.
Interpretive Summary: All vitamin K forms share a biochemical structure called menadione, but have different sidechains. Phylloquinone is the vitamin K form produced by plants, and menaquinones are the different vitamin K forms produced by bacteria, including gut bacteria. Not much is known about how dietary vitamin K influences the gut microbiota or the vitamin K forms it produces. We fed mice either a vitamin K deficient diet or vitamin K sufficient diets containing different forms of vitamin K. The vitamin K deficient diet significantly altered the gut microbiome compared to vitamin K sufficient diets in female mice. This was similar in male mice, but the effect was not as strong. To determine if the gut bacteria can use dietary vitamin K to make their own menaquinones, we fed mice stable-isotope labeled forms of vitamin K. In mice, gut bacteria formed menaquinones that contained the menadione from the dietary form given, but with a substituted side chain. When we supplemented human gut microbes in culture with stable isotope-labeled vitamin K forms, human gut microbes could only transform menadione to menaquinones. These results suggest that vitamin K deficiency alters the gut microbiome, and more research is needed to determine if menadione that is formed in intestinal tissue is an important intermediate in the remodeling of dietary vitamin K to bacterial menaquinones.
Technical Abstract: Vitamins have well-established roles in bacterial metabolism. Menaquinones (MKn, n=prenyl units in sidechain) are bacterially produced forms of vitamin K produced by the gut microbiota and consumed in the diet. Little is known about the influence of dietary vitamin K quinones on gut microbial composition and MKn production. Here, male and female C57BL6 mice were fed a vitamin K deficient diet or vitamin K sufficient diets containing phylloquinone (PK, plant-based vitamin K form), MK4, and/or MK9. DNA was extracted from cecal contents and 16S sequencing conducted to assess microbial composition. Cecal microbial community composition was significantly different in vitamin K deficient female mice compared to females on vitamin K sufficient diets (all p<0.007). Parallel trends were seen in male mice, but were not statistically significant (all p > 0.05 but <0.1). Next, stable isotope-labeled vitamin K quinones were supplemented to male and female C57BL6 mice (2H7PK, 13C11MK4, 2H7MK7, 2H7MK9) and to an in vitro fermentation model inoculated with human stool (2H7PK, 2H7MK4, 2H7MK9, or vitamin K precursor 2H8-menadione). Vitamin K quinones in feces and culture aliquots were measured using LC-MS. In vivo, supplemented vitamin K quinones were remodeled to other MKn (2H7- or 13C6-labeled MK4, MK10, MK11, and MK12), but in vitro only the precursor 2H8-menadione was remodeled to 2H7MK4, 2H7MK9, 2H7MK10, and 2H7MK11. These results suggest that dietary vitamin K deficiency alters the gut microbial community composition. Further studies are needed to determine if menadione generated by host metabolism may serve as an intermediate in dietary vitamin K remodeling in vivo.