(HealthDay News) — Vitamin D (VD) supplementation has a blunted response for participants with overweight or obesity, according to a study published online in JAMA Network Open.

Deirdre K. Tobias, ScD, from Brigham and Women’s Hospital in Boston, and colleagues investigated whether baseline body mass index (BMI) modifies vitamin D metabolism and response to supplementation. The analysis included participants of the Vitamin D and Omega-3 Trial who provided a blood sample at baseline (16,515 participants) and a repeated sample at 2 years (2742 participants).

The researchers found that at baseline, 25-hydroxyvitamin D3 (25[OH]D3), free VD, bioavailable VD, VD-binding protein, albumin, and calcium levels were lower with higher BMI, while parathyroid hormone level was higher. Randomization to VD supplementation was associated with an increase in total 25(OH)D, 25(OH)D3, free VD, and bioavailable VD levels versus placebo at follow-up, although increases were significantly lower at higher BMI categories. There was no substantial change in VD binding protein, albumin, parathyroid hormone, or calcium levels with supplementation.

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“BMI may be associated with modified response to vitamin D supplementation and may in part explain the observed diminished outcomes of supplementation for various health outcomes among individuals with higher BMI,” the authors write.

One author disclosed financial ties to the pharmaceutical industry.

Abstract/Full Text