|Centi, Amanda - Jean Mayer Human Nutrition Research Center On Aging At Tufts University|
|Shea, Kyla - Jean Mayer Human Nutrition Research Center On Aging At Tufts University|
|Gundberg, Caren - Yale University|
|Saltzman, Edward - 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: Journal of Federation of American Societies for Experimental Biology
Publication Type: Abstract Only
Publication Acceptance Date: 2/6/2015
Publication Date: 4/1/2015
Citation: Centi, A., Shea, K., Gundberg, C., Saltzman, E., Booth, S.L. 2015. Decreases in circulating uncarboxylated osteocalcin are not associated with HOMA-IR changes in humans. Journal of Federation of American Societies for Experimental Biology. 29(2):758.10.
Technical Abstract: Osteocalcin (OC) in its uncarboxylated form (ucOC) may improve glucose metabolism in mice. However, human data are equivocal. Vitamin K (VK) is the only known factor to reduce the proportion of circulating OC that is uncarboxylated. We hypothesized that a decrease in circulating ucOC through VK supplementation would increase insulin resistance (IR) measures in humans. Serum was collected from weight-stable older and younger men and women (n=42) before and after 28d of VK supplementation (500 micrograms phylloquinone/d). All meals and beverages were provided to control for other nutrients. The primary outcome was defined as IR change as assessed by the homeostatic model (HOMA-IR). Total OC (tOC), ucOC and insulin were measured by radioimmuno assay. Glucose was measured by an enzymatic kinetic method. Measured covariates included triglycerides, BMI, age group and sex. A repeated measures ANOVA was used to determine if decreases in ucOC increased HOMA-IR. In response to VK supplementation, significant decreases in circulating ucOC (pre = 4.79 +/- 2.61 ng/mL post = 1.59 +/- 2.11 ng/mL, p<0.001) and tOC (pre = 9.19 +/- 4.05 ng/mL post = 8.48 +/- 3.86 ng/mL, p=0.015) were observed. However, there were no significant changes in HOMA-IR (pre = 2.20 +/- 0.98 post = 2.25 +/- 1.12, p=0.78). Further, no differences in HOMA-IR were observed between sexes (p=0.39) or age groups (p=0.20) in relation to decreases in circulating ucOC or tOC. The lack of association between changes in circulating ucOC and HOMA-IR suggests that in humans, ucOC does not have a role in IR.