Research synthesisLow evidenceMixed effect size4 studies · 2 beneficial · 2 neutral · 0 harmful
Across 4 studies, 2 found beneficial effects on gait speed (effect sizes ranged from small to large) and 2 found neutral effects, indicating mixed evidence. The median study duration was 112 days, with benefits observed primarily in clinical populations such as COPD patients and elderly with sarcopenia, but not in generally healthy older adults.
- Studied populations: Patients with chronic obstructive pulmonary disease (COPD) and elderly individuals with sarcopenia
Caveats: Beneficial effects were seen in studies where vitamin D was combined with whey protein or evaluated in a network meta-analysis; studies testing vitamin D alone, including a large 3-year trial in generally healthy older adults, found no significant effect on gait speed. This suggests any benefit may require co-administration with protein or be restricted to specific deficient or clinical populations. The only specified dose (2000 IU/day) was associated with a neutral outcome.
Generated Jul 12, 2026