Vitamin D in the Middle East and North Africa

Abstract

PurposeThe Middle East and North Africa (MENA) region registers some of the lowest serum 25‑hydroxyvitamin D [25(OH)D] concentrations, worldwide. We describe the prevalence and the risk factors for hypovitaminosis D, completed and ongoing clinical trials, and available guidelines for vitamin D supplementation in this region.MethodsThis review is an update of previous reviews published by our group in 2013 for observational studies, and in 2015 for randomized controlled trials (RCTs) from the region. We conducted a comprehensive search in Medline, PubMed, and Embase, and the Cochrane Library, using MeSH terms and keywords relevant to vitamin D, vitamin D deficiency, and the MENA region, for the period 2012–2017 for observational studies, and 2015–2017 for RCTs. We included large cross-sectional studies with at least 100 subjects/study, and RCTs with at least 50 participants per arm.ResultsWe identified 41 observational studies. The prevalence of hypovitaminosis D, defined as a 25‑hydroxyvitamin D [25(OH)D] level below the desirable level of 20 ng/ml, ranged between 12–96% in children and adolescents, and 54–90% in pregnant women. In adults, it ranged between 44 and 96%, and the mean 25(OH)D varied between 11 and 20 ng/ml. In general, significant predictors of low 25(OH)D levels were female gender, increasing age and body mass index, veiling, winter season, use of sun screens, lower socioeconomic status, and higher latitude.We retrieved 14 RCTs comparing supplementation to control or placebo, published during the period 2015-2017: 2 in children, 8 in adults, and 4 in pregnant women. In children and adolescents, a vitamin D dose of 1000–2000 IU/d was needed to maintain serum 25(OH)D level at target. In adults and pregnant women, the increment in 25(OH)D level was inversely proportional to the dose, ranging between 0.9 and 3 ng/ml per 100 IU/d for doses ≤2000 IU/d, and between 0.1 and 0.6 ng/ml per 100 IU/d for doses ≥3000 IU/d. While the effect of vitamin D supplementation on glycemic indices is still controversial in adults, vitamin D supplementation may be protective against gestational diabetes mellitus in pregnant women. In the only identified study in the elderly, there was no significant difference between 600 IU/day and 3750 IU/day doses on bone mineral density. We did not identify any fracture studies.The available vitamin D guidelines in the region are based on expert opinion, with recommended doses between 400 and 2000 IU/d, depending on the age category, and country.ConclusionHypovitaminosis D is prevalent in the MENA region, and doses of 1000–2000 IU/d may be necessary to reach a desirable 25(OH)D level of 20 ng/ml. Studies assessing the effect of such doses of vitamin D on major outcomes, and confirming their long term safety, are needed.

Is there any link between vitamin D deficiency and vasovagal syncope?

“…In contrast to our findings, some studies investigating vitamin D levels in the general population found that vitamin D levels were lower in those with male gender and high BMI values . One of the important meta‐analysis results showed that low 25(OH)D levels (<20 ng/mL) were more prevalent in women, and vitamin D deficiency was more common in individuals with high BMI values …”

The prevalence of vitamin D deficiency between Saudis and non-Saudis in Al-Madinah Al-Munawarah a cross-sectional study

“…Furthermore, Barchetta and colleagues in 2011 found that higher vitamin D deficiency was accompanied by increasing BMI and waist circumference (33). Chakhtoura and colleagues (2018) documented in their review on the prevalence of vitamin D deficiency in the Middle East and North Africa that higher BMI was one of the predictors of reduced serum vitamin D levels (13).…”

“…Chakhtoura and colleagues, in their systematic review in 2018, have reviewed trials that studied the vitamin D deficiency in the MENA region. They indicated that smoking status was one of the possible consistent predictors of vitamin D deficiency (13).…”

“…In the Middle East and North Africa (MENA), especially the Kingdom of Saudi Arabia (KSA), high prevalence of vitamin D deficiency has been reported despite the abundance of sunshine (12,13). In 2015, a cross-sectional national multistage surveyreported that the prevalence of vitamin D deficiency was 40.6% in male Saudis and 62.65% in female Saudis (14).…”

Parathormone Levels in a Middle-Eastern Healthy Population Using 2nd and 3rd Generation PTH Assays

“…Reference values for PTH are available in European [13,14], United States [15], and Chinese populations [16]. However, normative PTH values are lacking in the Middle-East, more particularly in Lebanon, a part of the world known for its high prevalence of vitamin D deficiency [17,18]. In addition, reference values were mainly established using either 2 nd or 3 rd generation PTH assays.…”