Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/11/2010
Publication Date: 5/1/2010
Citation: Shea, K., Booth, S.L., Gundberg, C.M., Peterson, J.W., Waddell, C., Dawson-Hughes, B., Saltzman, E. 2010. Adulthood obesity is positively associated with adipose tissue concentrations of vitamin K and inversely associated with circulating indicators of vitamin K status in men and women. Journal of Nutrition. 140:1029-1034. Interpretive Summary: Overweight and obese people are at higher risk for low fat-soluble nutrient status. Fat tissue contains high amounts of the fat-soluble vitamins A, D, and E, so fat-soluble nutrients may be sequestered in fat tissue. The extent to which vitamin K, which is also fat-soluble, is stored in human fat is not known, and whether or not increased body fat is associated with lower vitamin K status has not yet been studied in humans. We developed an analytical method to measure vitamin K in human adipose tissue, measured the vitamin K content of fat samples taken from 16 patients undergoing gastric bypass surgery, and found that vitamin K concentrations in human fat are much higher than in other organs known to store vitamin K. In a separate study, we determined the association between percent body fat and blood measures of vitamin K status in 183 men and 260 post-menopausal women, all of who were between 60-80 yrs old. The men and women with the higher percent body fat had lower vitamin K status. The relationships between body fat, vitamin K status, and vitamin K content of fat tissue need to be clarified in future studies.
Technical Abstract: Increased adiposity is associated with increased storage of several fat-soluble nutrients. However, the extent to which vitamin K is stored in fat and the association between vitamin K status and adiposity are unknown. The objectives of this study are to determine (1) if vitamin K is stored in human adipose tissue, and (2) the association between vitamin K status and body fat in older men and women. In study A, the vitamin K content of human subcutaneous and visceral adipose tissue was quantified in samples taken from 16 gastric bypass patients [13F, mean(SD) age=40(10)yrs] using HPLC. In study B, cross-sectional associations between percent body fat (%BF) and circulating measures of vitamin K status were examined in 260 women and 183 men [mean(SD) age=68(5)yrs]. The mean (SD) phylloquinone concentrations in subcutaneous and visceral adipose tissue were 148.2(71.8) and 175(112) nmol/kg, respectively, which is higher than reported concentrations of other organs known to store vitamin K. There was an inverse association between %BF and plasma phylloquinone in women (p-trend<0.001). Higher %BF was associated with greater circulating concentrations of uncarboxylated prothrombin (PIVKA-II), indicative of lower vitamin K status (p-trend=0.02 and 0.002 for men and women, respectively), but not with percentage undercarboxylated osteocalcin. Adipose tissue contained high concentrations of vitamin K, and increased adiposity was associated with poorer vitamin K status in older adults. Additional studies are needed to further explore the relationships between body fat, storage of vitamin K in adipose tissue, and implications for vitamin K status and function.