A systematic review and meta-analysis of 12 randomised controlled trials encompassing 8,023 adults from Black African, South Asian, South Korean, and Chinese populations found that vitamin D supplementation — ranging from 400 to 6,400 IU/day over 3 months to 5.3 years — produced minimal clinically meaningful improvements in bone health. Of eight trials measuring bone mineral density, only one showed significant gains (femoral neck and trochanter BMD at 12 months with just 400 IU/day in South Asians). The headline meta-analytic finding of elevated bone alkaline phosphatase (BALP) — a bone formation marker — evaporated after removing a single confounded trial where both arms received the bisphosphonate risedronate, leaving no statistically significant pooled effect.
This matters because non-White populations carry a disproportionate burden of vitamin D deficiency due to melanin-related reductions in cutaneous synthesis, yet most prior bone-health trials enrolled predominantly White European cohorts. The implicit assumption that supplementation benefits would translate across ethnicities appears unsupported by the available evidence. That said, only one trial — covering 5,106 participants — examined fracture incidence, the clinically decisive outcome, finding no significant difference. Twelve trials is a thin evidence base for a population of billions, and substantial heterogeneity (I² = 97.1%) limits confidence in pooled estimates. Clinicians should resist blanket supplementation prescriptions for bone protection in non-White adults while acknowledging that correcting frank deficiency for immune and muscular health remains a separate, better-supported rationale.