Impact of vitamin D replacement in adults and elderly in the Middle East and North Africa: a systematic review and meta-analysis of randomized controlled trials.

Abstract

Hypovitaminosis D is prevalent worldwide, more so in the Middle East and North Africa (MENA). This study aims to determine the effects of vitamin D replacement on the mean difference in 25-hydroxyvitamin D [25(OH)D] level reached and other outcomes, in the MENA. This is a meta-analysis of randomized trials from the MENA, administering vitamin D supplementation for at least 3months, without language or time restriction. We conducted a comprehensive search in seven databases until July 2015. We abstracted data from published reports, independently and in duplicate. We calculated the mean difference (MD) and 95% CI of 25(OH)D level reached for eligible comparisons, and pooled data using RevMan version 5.3. We identified 2 studies in elderly and 17 in adults; for the latter, 11 were included in the meta-analysis. Comparing a high vitamin D dose (>2000IU/day) to placebo (nine studies), the MD in 25(OH)D level achieved was 18.3 (CI 14.1; 22.5)ng/ml; p value<0.001; I 2=92%. Comparing an intermediate dose (800-2000IU/day) to placebo (two studies), the MD in 25(OH)D level achieved was 14.7 (CI 4.6; 24.9)ng/ml; p value 0.004; I 2=91%. Accordingly, 89 and 71% of participants, in the high and intermediate dose groups, respectively, reached the desirable level of 20ng/ml. The risk of bias in the included studies was unclear to high, except for three studies. In the MENA region, vitamin D doses ≥2000IU/day may be needed to reach the target 25(OH)D level ≥20ng/ml. The long-term safety and the efficacy of such doses on various outcomes are unknown.