25(OH)D status: Effect of D3 supplement

BACKGROUND Excess adipose tissue may lead to sequestrating of vitamin D, making it less available for use in the body. OBJECTIVE This study determined if overweight or obese individuals (BMI > 25 kg m-2) had insufficient (<30 ng mL-1) levels of 25-hydroxyvitamin D [25(OH)D] and, if so, would serum levels respond to exogenous supplementation. METHODS Sixty-three women who were overweight/obese (BMI = 31.07 ± 5.00 kg m-2) were randomly assigned in a double-blind manner to receive 5,000 IU of vitamin D3 (D3) (n = 31) or a placebo (PL) (n = 32) daily. Serum 25(OH)D concentrations were measured by finger-stick analyses at baseline and after 8 weeks of supplementation. Data were analyzed by using a 2 × 2 (group × time) repeated measure multivariate analysis of variance to determine group differences for pre-values and post-values (p < 0.05). RESULTS On day one of the study, both D3 and PL groups had insufficient levels of vitamin D (mean ± SD) 24.03 ± 9.78 ng mL-1 and 23.62 ± 9.77 ng mL-1, respectively. After 8 weeks of supplementation, the D3 group 25(OH)D level rose to a mean of 43.57 ± 10.87 ng mL-1 (p < 0.001) versus the PL group whose 25(OH)D level remained statistically unchanged 24.31 ± 8.84 ng mL-1. Women who were overweight/obese had insufficient vitamin D levels prior to supplementation. CONCLUSIONS Following supplementation with 5,000 IU of vitamin D3, all subjects' 25(OH)D levels rose to a sufficient level (≥30 ng mL-1). The findings of this study concur with the Institute of Medicine and Endocrine Society recommendations in that two to three times the daily requirement of vitamin D is required to improve serum vitamin D levels in individuals who are overweight or obese.