Associations between body fat and vitamin K status in older women

Fat soluble nutrients are stored in fat tissue. Yet, the association between body fat and vitamin K status is not clear. We examined associations between % body fat (%BF) and 3 circulating measures of vitamin K status [plasma phylloquinone (plasma K1), uncarboxylated prothrombin (PIVKA), uncarboxylated osteocalcin (%ucOC)] cross‐sectionally in 262 women (60‐80 yrs) using analysis of covariance adjusted for age, vitamin K intake, triglycerides, and smoking. Higher %BF was associated with lower plasma K1 (p‐trend<0.01) and higher PIVKA (p‐trend<0.01), both indicative of lower vitamin K status. There was a non‐significant trend, but %ucOC did not differ across %BF tertiles (p=0.08). Linear regression was then used to assess the association between plasma K1 and the functional measures of PIVKA and %ucOC (as outcomes) in the separate %BF tertiles. The strength of the inverse association between plasma K1 and PIVKA increased across tertiles: unstd βT1:‐0.33(p=0.08), T2:‐0.45 (p=0.02), and T3:‐0.51(p=0.02), while the association between plasma K1 and %ucOC was weaker and non‐significant among women in the highest %BF tertile: unstd βT1:‐9.9(p=0.01), T2:‐18.9(p<0.01), and T3:‐3.0(p=0.50). Further studies are needed to elucidate the meaning of the associations between body fat and the measures of vitamin K status. Research support: NIA A914759 & USDA ARS (cooperative agreement 58‐1950‐7‐707)