CONCLUSION: Although there is insufficient evidence that vitamin D supplementation alone improves physical performance in older people, some data suggest a benefit from vitamin D combined with calcium

The gap

Consensus across the literature

Supporting evidence — 4 representative gaps

• Functional and Symptomatic Effects of Vitamin D Supplementation Following Carpal Tunnel Release: A Randomized Controlled Trial (2026) · doi

  This study had several limitations. First, serum vitamin D levels were not measured before or after treatment, which precludes analysis of whether baseline deficiency or achieved serum concentrations influenced the outcomes. However, epidemiological studies in Thailand and other Asian populations have shown that vitamin D insufficiency common, particularly among urban residents and women, thus providing a clinical context for evaluating vitamin D supplementation. However, the absence of biochemical assessments remains an important limitation. relatively remains Second, the 12-week follow-up period may not have been sufficient to capture longer-term motor recovery or the potential delayed benefits of supplementation. Third, the relatively small sample size may have limited the statistical power to detect subtle intergroup differences.

  Keywords: vitamin serum supplementation remains relatively several limitations first levels measured treatment precludes whether baseline deficiency
• Prevalence of Hypovitaminosis D Among Patients With Type 2 Diabetes Mellitus: Evidence From a Diabetes Clinic in Durgapur, West Bengal (2026) · doi

  The use of multivariable logistic regression enabled adjustment for potential confounders and the identification of independent predictors of hypovitaminosis D. However, because this was a hospital-based cross-sectional study, the findings may not be fully generalizable to the broader community. The relatively high absolute error (10%) used in sample size calculation resulted in a modest sample size. Berksonian bias may also have influenced the findings. Additionally, the cross-sectional design precludes causal inference regarding the relationship between vitamin D status and microvascular complications. Biochemical markers such as parathyroid hormone, serum calcium, phosphate, and inflammatory markers were not assessed, which limits mechanistic interpretation. Further multicentric studies with larger sample sizes are recommended to improve external validity and confirm these findings.

  Keywords: sample cross sectional size markers multivariable logistic regression enabled adjustment potential confounders identification independent predictors
• A study of 25‑(OH)D ₃ levels in children with type 1 diabetes mellitus and its influencing factors (2026) · doi

  However, due to the observational design, the absence of matching for key confounders, and the lack of data on important covariates such as BMI, dietary intake and sun exposure, the findings support only associations and cannot establish causality. Finally, the effects of vitamin D supplementation on patients with T1DM were not investigated.

  Keywords: observational design absence matching confounders lack important covariates dietary intake exposure support associations cannot establish
• Effects of Vitamin D Supplementation on Strength, Physical Performance, and Falls in Older Persons: A Systematic Review (2003) · doi

  CONCLUSION: Although there is insufficient evidence that vitamin D supplementation alone improves physical performance in older people, some data suggest a benefit from vitamin D combined with calcium supplementation, but this requires confirmation in large, well-designed trials.

  Keywords: vitamin supplementation conclusion there insufficient evidence alone improves physical performance older people suggest benefit combined