Relationship between Vitamin D Status and the Risk of Obesity without Diagnosed Metabolic Syndrome: A Meta-Analysis of Observational Studies.

In 30 seconds

This systematic review and meta-analysis pooled observational studies examining vitamin D status and obesity without diagnosed metabolic syndrome. Across 74 studies involving 110,838 individuals, serum or plasma 25-hydroxyvitamin D concentrations were lower in participants with obesity than in controls (mean difference=-3.98; 95% confidence interval [CI], -4.70 to -3.27). Vitamin D deficiency was also more prevalent with obesity (odds ratio [OR], 2.02; 95% CI, 1.73 to 2.36), while insufficiency showed a smaller association. Results varied by measurement method and deficiency criteria, so the findings indicate association rather than evidence that vitamin D status causes obesity.

Key findings

• 25-hydroxyvitamin D concentrations were lower in obesity than in controls (mean difference=-3.98; 95% CI, -4.70 to -3.27).
• Vitamin D deficiency was more prevalent among participants with obesity (OR, 2.02; 95% CI, 1.73 to 2.36).
• Vitamin D insufficiency was associated with obesity (OR, 1.17; 95% CI, 1.04 to 1.32), with significant differences limited to specified subgroups.
• Associations were not significant in studies using LC-MS/MS for concentration comparisons or deficiency thresholds below 10 or 12 ng/mL.

Why it matters

The pooled findings suggest that lower vitamin D status commonly accompanies obesity even in the absence of diagnosed metabolic syndrome. This may help clinicians interpret vitamin D measurements in this population, while the variation across assays and thresholds cautions against treating the association as uniform or causal. The observational evidence does not establish whether low vitamin D precedes obesity or results from it.

What to keep in mind

The analysis included observational studies, which cannot establish causality. Findings also varied according to vitamin D detection methods and assessment criteria.