Vitamin K Status in Black and White Older Adults and its Relationship with Cardiovascular Disease Risk

Abstract

Vitamin K (VK) dependent proteins, such as matrix gla protein (MGP), are present in cardiovascular tissue. VK supplementation reduces arterial calcification, a marker of cardiovascular disease (CVD). Observational studies suggest higher VK intake is associated with lower CVD risk. Nutritional biomarkers are more objective measures of nutrient status than self‐reported intakes but the association between VK biomarkers and incident CVD has not been reported. We determined the association between VK status and incident CVD by measuring plasma phylloquinone (PK, vitamin K1) and uncarboxylated MGP (ucMGP) in 319 black and 385 white community‐dwelling older adults free of clinical CVD (67%F, 74±3yrs). Compared to whites, blacks were significantly less likely to have low plasma PK (defined as <0.2nM) [OR(95%CI) 0.46(0.21‐0.98)] and high ucMGP (reflective of lower VK status; defined as highest tertile) [OR(95%CI) 0.30(0.20‐0.46)]. There were 92 incident CVD events in whites and 78 in blacks after 12 years. In models adjusted for demographics, lifestyle factors and CVD risk factors, the HR(95%CI) for incident CVD associated with low plasma PK was 1.46(0.69‐3.09) in whites and 1.18(0.47‐3.01) in blacks. The adjusted HR(95%CI) for incident CVD associated with high ucMGP was 0.78(0.48‐1.28) in whites and 0.88 (0.47‐1.63) in blacks. VK status was not associated with incident CVD in blacks or whites, but the precision of our estimates suggests larger racially‐diverse studies are needed to clarify the relevance of VK nutritional status to CVD among racial groups. That low VK status was more prevalent in whites compared to blacks merits consideration in future studies of VK nutrition.