Effects of vitamin D intake alone on elderly body composition: A systematic review and meta-analysis of RCTs.

Vitamin D intake was not associated with an increase in skeletal muscle mass index (SMI) compared to the control group in elderly individuals.

• Seven randomized controlled trials met eligibility criteria for inclusion in the meta-analysis.
• Mean age of participants ranged from 60 to 74 years across included studies.
• Participant sample sizes ranged from 50 to 1094 per study.
• Study durations ranged from 3 to 36 months.
• The primary outcome was the change in SMI between vitamin D and control groups.

Vitamin D intake was associated with a decrease in fat mass (FM) compared to the control group.

• This finding was observed in the overall meta-analysis including all seven RCTs.
• However, when studies using active vitamin D were excluded, the decrease in FM was no longer observed.
• The mean baseline 25(OH)D concentration across studies ranged from 15.1 to 33.0 ng/mL.
• The decrease in FM was described as a 'possible decrease,' suggesting the effect may be driven by studies using active vitamin D formulations.

Vitamin D intake was not associated with increases in lean mass (LM) compared to the control group.

• LM was included as a secondary outcome in the meta-analysis.
• This finding held in both the overall analysis and in the subgroup analysis excluding studies that used active vitamin D.
• Seven RCTs were included in the analysis with study durations ranging from 3 to 36 months.

Vitamin D intake was not associated with increases in handgrip strength compared to the control group.

• Handgrip strength was included as a secondary outcome.
• The null finding for handgrip strength was consistent in both the full analysis and in the meta-analysis excluding studies using active vitamin D.
• Participants spanned a mean age range of 60 to 74 years across included trials.

When studies using active vitamin D were excluded from the meta-analysis, vitamin D intake was not associated with changes in SMI, LM, handgrip strength, or FM.

• This subgroup analysis was conducted to isolate the effect of native (non-active) vitamin D supplementation.
• The reduction in FM observed in the full analysis was no longer present after excluding active vitamin D studies.
• This suggests that any observed FM reduction may be attributable specifically to active vitamin D formulations rather than standard vitamin D supplementation.
• Databases searched included PubMed, Embase, and Cochrane from inception to April 22, 2024.