Fewer than half of pregnancies will get even 20 ng of vitamin D with 800 IU daily dose – meta-analysis
Vitamin D replacement in children, adolescents and pregnant women in the Middle East and North Africa: A systematic review and meta-analysis of randomized controlled trials.
Metabolism. 2017 May;70:160-176. doi: 10.1016/j.metabol.2017.02.009. Epub 2017 Feb 16.
Chakhtoura M1, El Ghandour S2, Shawwa K3, Akl EA4, Arabi A5, Mahfoud Z6, Habib R3, Hoballah H2, El Hajj Fuleihan G5.
INTRODUCTION:
Hypovitaminosis D affects one-third to two-thirds of children and pregnant women from the Middle East and North Africa (MENA) region.
OBJECTIVE:
To evaluate in infants, children, adolescents and pregnant women, from the MENA region, the effect of supplementation with different vitamin D doses on the change in 25-hydroxyvitamin D [25(OH)D] level reached, and other skeletal and non-skeletal outcomes.
METHODS:
This is a systematic review of randomized controlled trials of vitamin D supplementation conducted in the MENA region. We conducted a comprehensive literature search in 7 databases, without language or time restriction, until November 2016. Two reviewers abstracted data from the included studies, independently and in duplicate. We calculated the mean difference (MD) and 95% CI of 25(OH)D level reached when at least 2 studies were eligible in each comparison (low (<800IU), intermediate (800-2000IU) or high (>2000IU) daily dose of vitamin D, or placebo). We pooled data using RevMan version 5.3.
RESULTS:
We identified a total of 15 eligible trials: one in infants, 4 in children and adolescents and 10 in pregnant women. In children and adolescents, an intermediate vitamin D dose (1901IU/d), resulted in a mean difference in 25(OH)D level of 13.5 (95% confidence interval (CI) 8.1-18.8) ng/ml, compared to placebo, favoring the intermediate dose (p<0.001). The proportion of children and adolescents reaching a 25(OH)D level≥ 20ng/ml was 74% in the intermediate dose group. In pregnant women, four trials started supplementation at 12-16weeks of gestation and continued until delivery, and six trials started supplementation at 20-28weeks' gestation and stopped it at delivery. The MD in 25(OH)D level reached was 8.6 (95% CI 5.3-11.9) ng/ml (p<0.001) comparing the high dose (3662IU/d) to the intermediate dose (1836IU/d), and 12.3 (95% CI 6.4-18.2) ng/ml (p<0.001), comparing the high dose (3399IU/d) to the low dose (375IU/d). Comparing the intermediate (1832IU/d) to the low dose (301IU/d), the MD in 25(OH)D level achieved was 7.8 (95% CI 4.5-10.8) ng/ml (p<0.001).
The proportion of pregnant women reaching a 25(OH)D level≥20ng/ml was 80%-90%, 73% and 27%-43% in the high, intermediate, and low dose groups , respectively. The risk of bias in the included studies, for children, adolescents and pregnant women, ranged from low to high across all doamins.
CONCLUSION:
In children, adolescents and pregnant women from the MENA, an intermediate vitamin D dose of 1000-2000IU daily may be necessary to allow for the majority of the population to reach a desirable 25(OH)D level of 20ng/ml. Further high quality RCTs are required to confirm/refute the beneficial impact of vitamin D supplementation on various clinically important outcomes.
PMID: 28403940 DOI: 10.1016/j.metabol.2017.02.009