Effects of Vitamin D Supplementation in Combination With Exercise Training on Body Composition and Muscular Strength in Adults: A Systematic Review and Dose-Response Meta-Analysis of Randomized Controlled Trials.

In 30 seconds

This systematic review and dose-response meta-analysis of randomized controlled trials assessed whether vitamin D supplementation added to exercise improves body composition or muscular strength compared with exercise alone in adults. Across 28 studies involving 1675 participants, combined supplementation and exercise increased 25(OH)D by 34.11 nmol/L (P = .001). There were no significant between-group effects on body weight, BMI, fat mass, body fat percentage, fat-free mass, or leg press strength. Knee extension strength improved modestly (WMD, 4.36 kg; P = .039); handgrip benefits were reported in older adults and participants receiving higher doses.

Key findings

• Combined vitamin D and exercise increased 25(OH)D by 34.11 nmol/L versus exercise alone (P = .001).
• No significant effects were found for body weight, BMI, fat mass, body fat percentage, fat-free mass, or leg press strength (all P > .05).
• Knee extension strength improved modestly (WMD, 4.36 kg; P = .039).
• Handgrip strength improved significantly in older adults and in participants receiving higher vitamin D doses.

Why it matters

The findings distinguish a reliable increase in vitamin D status from broader functional or body-composition benefits. For clinicians interpreting supplementation alongside exercise, the pooled evidence does not show improved body composition or most strength outcomes, although selected strength measures and subgroups showed benefits. This helps set realistic expectations while highlighting areas where effects may vary.

What to keep in mind

The abstract does not report the number of participants contributing to each outcome or provide estimates of uncertainty beyond P values, limiting assessment of the precision of individual findings.