Optimal dose of vitamin D replacement : a systematic review and meta-analysis of randomized controlled trials from the Middle East and North Africa -

Abstract

Background: Hypovitaminosis D, defined as a 25-hydroxyvitamin D (25(OH)D) level 20 ng-ml, is highly prevalent worldwide, more so in the Middle East and North Africa (MENA) region. Relevant risk factors in adults, specific to the MENA region, include multiparity, clothing style and veiling, season, socio-economic status, urban living and the lack of governmental regulation of food fortification. The latest Institute of Medicine (IOM) recommendations for vitamin D supplementation targeted populations from North America, and may not necessarily apply to the MENA region. The WHO does not have any current guidelines on this topic, with the exception of guidelines in pregnancy.Objectives: The objectives of this systematic review and meta-analysis are: (1) determine the mean difference in 25(OH)D level reached with low ( 800 IU), moderate (800-2,000 IU) or high (2,000 IU) daily dose of vitamin D in subjects in MENA countries, by age and reproductive status, and estimate the proportion of subjects who reach a mean 25(OH) D level ≥ 20 ng-ml in above treatment groups; (2) determine the effect of vitamin D supplementation on other outcomes: fracture rates, mortality, hypercalcemia-hypercalciuria, bone mineral density, kidney stones and muscle strength; (3) describe the vitamin D dose response and identify the predictors of 25(OH)D level achieved following supplementation.Search methodology: A systematic search for English and Non-English articles was conducted using Medline, PubMed, the Cochrane Controlled Trials Register, EMBASE, Popline, Global Health Library, Index Medicus for WHO Eastern Mediterranean without any time restriction; search was updated in July 2015. Additional studies were identified on ClinicalTrial.gov and the WHO registry for clinical trial. Authors were contacted for unpublished data.Eligibility criteria: We considered randomized clinical trials comparing different doses of oral vitamin D supplementation or placebo in MENA countries, of both genders and all age categories, including pregnant