Dietary phylloquinone intake and risk of type 2 diabetes in elderly subjects at high risk of cardiovascular disease

Background: Limited evidence from human and animal studies has suggested that vitamin K has a potentially beneficial role in glucose metabolism and insulin resistance. Objective: We analyzed the cross-sectional and longitudinal associations between dietary phylloquinone intake and type 2 diabetes in elderly subjects at high cardiovascular risk. Design: Cross-sectional associations were tested in 1925 men and women in the Prevention with the Mediterranean Diet trial. A longitudinal analysis was conducted on 1069 individuals free of diabetes at baseline (median follow-up: 5.5 y). Biochemical and anthropometric variables were obtained yearly. Dietary intake was collected during each annual visit by using a food-frequency questionnaire, and phylloquinone intake was estimated by using the USDA database. The occurrence of type 2 diabetes during followup was assessed by using American Diabetes Association criteria. Results: Dietary phylloquinone at baseline was significantly lower in subjects who developed type 2 diabetes during the study. After adjustment for potential confounders, risk of incident diabetes was 17% lower for each additional intake of 100 mg phylloquinone/d. Moreover, subjects who increased their dietary intake of vitamin K during the follow-up had a 51% reduced risk of incident diabetes compared with subjects who decreased or did not change the amount of phylloquinone intake. Conclusion: We conclude that dietary phylloquinone intake is associated with reduced risk of type 2 diabetes. This trial was registered at http://www.controlled-trials.com as ISRCTN35739639. Am J Clin Nutr doi: 10.3945/ajcn.111.033498.