Correction of hypovitaminosis D does not improve the metabolic syndrome risk profile in a Chinese population: a randomized controlled trial for 1 year.

BACKGROUND AND OBJECTIVES: Vitamin D deficiency is associated with a variety of chronic metabolic diseases. In vitro and animal studies suggest that vitamin D may play a crucial role in obesity and related metabolic disorders. Limited evidence regarding vitamin D deficiency exists within the Chinese population. The aims of the present study were to assess whether supplementation with vitamin D would improve metabolic indices in a middle-aged urban Chinese population. METHODS AND STUDY DESIGN: We designed a randomized placebo controlled trial involving 126 metabolic syndrome sufferers with vitamin D deficiency, allocated to receive either a daily oral tablet contain 700 IU vitamin D or a matching placebo. Metabolic indices including body mass index, plasma glucose, lipid profile and other parameters were measured in subjects who completed a 12 months intervention trial. RESULTS: There were significantly higher serum 25(OH)D and lower serum parathyroid hormone in vitamin D treatment group after the 12 months intervention, but no significant effect was observed for the metabolic variables which included body mass index, blood pressure, blood glucose and lipids in both treatment and control groups. CONCLUSIONS: Correction of hypovitaminosis D did not improve the metabolic syndrome in this urban Chinese cohort. Further studies are warranted in order to elucidate the cause-effect relation between vitamin D status, obesity and related metabolic disorders.