Ethnic Differences in Response to Oral Vitamin D Supplementation: A Systematic Review and Meta-analysis.

Abstract

Individual variability in oral vitamin D supplement response hinders the understanding of its clinical impact, and while ethnicity has been implicated in this variability it has not been well described. The aim was to systematically assess the impact of ethnicity on response to oral vitamin D supplementation. The Web of Science and PubMed databases were searched for articles published from 1960 to the end of 2020. All trials in adults measuring 25(OH)D3 blood levels were included. Two reviewers independently extracted the data from the eligible studies. The change in 25(OH)D3 blood levels (95% CI) and P values were extracted, and grouped according to ethnicity, then subjected to random-effects meta-analysis. The primary outcome measurement was mean serum 25(OH)D3 levels and the secondary outcome was dose-adjusted mean serum 25(OH)D3 levels, both compared with baseline. A total of 18 studies were identified, and data from 1131 participants were extracted. Body mass index (BMI) and dose were significant covariates (Pearson correlation coefficient, P = .016 and .017) and were normalized in the meta-analysis to minimize heterogeneity, but latitude was not (P = .66). Meta-analysis showed an effect of ethnicity on dose and BMI-adjusted mean serum 25(OH)D3 levels compared with baseline (P < .00001, I2 = 98%). Asian and White study participants demonstrated a statistically higher increase in dose and BMI-adjusted 25(OH)D3 blood levels (183 nmol/L [95% CI, 163-203] and 173 nmol/L [95% CI, 152-194], respectively), compared with Arab and Black study participants (37 nmol/L [95% CI, 35-39] and 99 nmol/L [95% CI, 90-108]) using repeated t tests. Sensitivity analysis demonstrated that these findings were not impacted by potential study bias or the inclusion of immigrant populations. Ethnicity had an impact on oral vitamin D response. Further prospective studies should examine if ethnicity-based dose stratification in both clinical practice and clinical trials is warranted. PROSPERO registration no. CRD42023410076.