Discrepant association of serum C-3 epimer of 25-hydroxyvitamin D versus non-epimeric 25-hydroxyvitamin D with serum lipid levels

BACKGROUND: Low vitamin D status has been associated with a number of chronic diseases. For dyslipidemia, vitamin D deficiency has been associated with higher low density lipoprotein-cholesterol (LDL-C) in a number of studies, but with inconsistent results in clinical trials. The purpose of the present study is to explore the relative importance of 3-epi-25-hydroxyvitamin D (25(OH)D) as compared with the non-epimeric form in relation to serum lipid. METHOD: This study used data from 1068 randomly selected volunteers in the Thai 4(th) National Health Examination Survey (NHES IV). Serum 25(OH)D(2), 25(OH)D(3), 3-epi-25(OH)D(2) and 3-epi-25(OH)D(3) were analyzed by liquid chromatography–tandem mass spectrometry. RESULTS: There was no association between serum total 25(OH)D and serum LDL-C. However, circulating 3-epi-25(OH)D(3) was negatively related to serum LDL-C (r = −0.077, P <0.05), while no such association was found for non-epimeric 25(OH)D(3) (r =0.030, P = 0.33). On the other hand, both 3-epi-25(OH)D(3) (r = 0.175, P <0.001) and non-epimeric 25(OH)D(3) (r = 0.142, P <0.001) were positively related to serum triglyceride (TRIG) levels. In multiple linear regression models with age, gender, body mass index , urban residence, education, hypertension and education as covariates, it was found that 3-epi-25(OH)D(3) was independently associated with serum LDL-C (beta = −0.12, P <0.01), while non-epimeric 25(OH)D(3) was positively related to LDL-C (beta = 0.13, P = 0.002). For TRIG, there were positive association with 3-epi-25(OH)D(3) (beta = 0.27, P <0.001) and negative association with non-epimeric 25(OH)D(3) (beta = − 0.10, P = 0.011) independent of age, gender, urban resident and education. CONCLUSIONS: There is a discrepant association of 25(OH)D levels with serum lipids according to 25(OH)D epimeric forms.