The relationship between 25-hydroxyvitamin D and homocysteine in asymptomatic adults.

Abstract

Hyperhomocysteinemia is an independent risk factor for premature atherosclerosis and thromboembolism. 25-Hydroxyvitamin D [25(OH)D] may modulate the expression of genes involved in homocysteine metabolism. Little is known about the relationship between homocysteine and 25(OH)D. We hypothesized an inverse and nonlinear association between 25(OH)D and homocysteine. We analyzed data from the continuous National Health and Nutrition Examination Survey 2001-2006 for asymptomatic adults (≥18 y). Linear regression models with spline adjusted for cardiovascular disease risk factors were used to explore nonlinearity. Mean change (β-coefficients with 95% confidence intervals) in homocysteine was reported per 10 ng/mL change in 25(OH)D. Mean (SD) age and homocysteine levels of 14 630 participants were 47.2 (20) years and 8.8 (4.7) μmol/L, respectively, whereas the median (interquartile range) of 25(OH)D was 21 (15-27) ng/mL. Without using spline, we observed an inverse relation between homocysteine and 25(OH)D both in simple [-0.25 (-0.34 to -0.02) μmol/L] and multivariable [-0.13 (-0.18 to -0.01) μmol/L] regression. With spline, in a univariate model, an increase in 25(OH)D was associated with a significant decrease in homocysteine [-0.56 (-0.75 to -0.37) μmol/L] until 25(OH)D reaches but not if above its median (21 ng/mL). Similarly, in multivariable spline models, the inverse relationship between homocysteine and 25(OH)D remain significant [-0.49 (-0.67 to -0.31) μmol/L] only below the population median of 25(OH)D. From a large community-based cohort of asymptomatic adults, we found an inverse relation between 25(OH)D and homocysteine among those with 25(OH)D concentration of 21 ng/mL or less. We did not observe any statistical decrease in homocysteine once 25(OH)D concentration rose above 21 ng/mL.