Dietary phylloquinone intakes and metabolic syndrome in US young adults

The relationship between dietary intake of vitamin K and metabolic syndrome (MetS) has not been investigated previously. The aim of this study was to examine whether and to what extent vitamin K intake measured as phylloquinone is related to MetS.

We performed a cross-sectional analysis on data from 5800 adults aged 20 to 45 years who participated in the National Health and Nutrition Examination Survey (NHANES) 1999-2004. MetS was defined according to Adult Treatment Panel III criteria. Dietary phylloquinone intakes were obtained from 24-hour dietary recall. Prevalence and odds ratios (OR) of MetS and its components were assessed by quartiles of dietary phylloquinone intake.

The lowest prevalence of MetS and its 5 components was observed in individuals with the highest phylloquinone intake. The prevalence of low high-density lipoprotein cholesterol (HDL) and elevated blood pressure progressively decreased with increasing phylloquinone intake (p < 0.05 for trend). HDL and C-reactive protein (CRP) levels improved gradually with increasing dietary phylloquinone intake (p < 0.05 for trend). In general, participants who had MetS or its element consumed less phylloquinone from diet compared those who did not. In comparison with the lowest phylloquinone intake quartile, the highest quartile of intake was associated with significantly reduced risks of low HDL level, hypertriglyceridemia, and hyperglycemia after adjustment was made for various nondietary confounding factors (OR, 0.73, 95% confidence interval [CI], 0.45-0.98; OR, 0.51, 95% CI, 0.25-0.97; and OR, 0.18, 95% CI, 0.05-0.73, respectively). Only the association between hyperglycemia and phylloquinone intake remained significant after further adjustment for dietary confounders (OR, 0.18, 95% CI, 0.05-0.73).

Mean reported dietary phylloquinone intakes suggested that most US young adults consume an insufficient amount of vitamin K from their diet. A high intake of phylloquinone may favorably affect MetS or its components, probably through an overall more heart-healthy dietary pattern. The pathogenesis of MetS is profoundly complex and may involve other factors and/or mechanisms, in addition to vitamin K nutriture. Although our data suggest a potential role of vitamin K in MetS, the biological mechanisms underlying the observed associations must be elucidated.