Association Between Low Blood 25-Hydroxyvitamin D and High C-Reactive Protein Levels in Community-Dwelling Japanese People Aged 40-74 Years

Abstract

Low blood 25-hydroxyvitamin D (25[OH]D) levels at which C-reactive protein (CRP) levels begin to rise vary. This study investigated the association between blood 25(OH)D and elevated CRP levels and determine the cut-off of low 25(OH)D for elevated CRP in middle-aged and older individuals in the Murakami cohort, Japan. This study used a cross-sectional study design with 2,863 subjects aged 40-74 years living in the community. Plasma 25(OH)D levels were determined with the Liaison® 25OH Vitamin D Total Assay, and serum high sensitivity CRP (hs-CRP) levels were determined with a latex nephelometry assay using an automatic analyzer. Multivariate logistic regression analysis was used to calculate odds ratios (ORs) for high hs-CRP (≥ 3 mg/L) with covariates including sex, age, BMI, physical activity, smoking, drinking, and disease history. Median age of subjects was 65 years, and median 25(OH)D level was 47.4 nmol/L. The proportion of subjects with high hs-CRP levels was 4.1%. The adjusted OR of 25(OH)D < 20 nmol/L was higher (OR = 3.22, 95% CI: 1.42-7.31) than that of the reference (25[OH]D 40-49 nmol/L). In subgroup analysis, the adjusted OR of 25(OH)D < 20 nmol/L was significantly higher than the reference in the BMI ≥ 22.8 (median) group (OR = 4.52) but not in the BMI < 22.8 group (OR = 1.61) (P for interaction = 0.0892), and the adjusted OR was significantly higher in the age ≥ 65 group (OR = 8.51) but not in the age < 65 group (OR = 2.22). Low blood 25(OH)D and high CRP levels were associated, with 25(OH)D 20 nmol/L being the cut-off, which was lower than previously reported values.

Keywords: 25-hydroxyvitamin D; C-reactive protein; cross-sectional study; low-grade chronic inflammation; vitamin D.