Phylloquinone supplementation improves glycemic status independent of the effects of adiponectin levels in premonopause women with prediabetes: a double-blind randomized controlled clinical trial

BACKGROUND: Vitamin K, as a cofactor in the gamma carboxylation of certain glutamic acid (Gla) residues, has been related to glucose metabolism and insulin sensitivity. Osteocalcin, also known as bone γ-carboxyglutamic acid, increases β-cell proliferation as well as insulin and adiponectin secretion, which improve glucose tolerance and insulin sensitivity. Thus, the purpose of the present study was to examine the possible role of adiponectin as a mediator of glucose homeostasis following phylloquinone supplementation in premonopause women with prediabetes. METHODS: Eighty two women were randomized to consume vitamin k1 supplement (n = 39) or placebo (n = 43) for four weeks. Participants in vitamin K1 treatment group received one pearl softgel capsule containing 1000 micrograms phylloquinone while the placebo group received one placebo capsules daily for four weeks. The Blood samples were collected at baseline and after a four-week intervention to quantify osteocalcin, adiponectin, leptin and relevant variables. RESULTS: Phylloquinone supplementation significantly increased serum adiponectin concentration (1.24 ± 1.90 compared with −0.27 ± 1.08 μg/ml), and did not alter total osteocalcin (0.50 ± 4.11 compared with 0.13 ± 1.85 ng/ml) and leptin (−0.29 ± 8.23 compared with −1.15 ± 5.25 ng/ml) compared with placebo. Adjustments for total osteocalcin and adiponectin using analysis of covariance (ANCOVA) did not affect the association of glycemic status with related variables. CONCLUSIONS: In conclusion our study demonstrated that phylloquinone supplementation improved glycemic status in premonopausal prediabetic women independent of adiponectin. TRIAL REGISTRATION: This trial was registered in Iranian Registry of Clinical Trials with ID number of IRCT2013120915724N1.