Effect of vitamin A supplementation on iron status in humans: A systematic review and meta-analysis

Abstract

Anemia is a worldwide public health problem that can be related to many causes, including vitamin A deficiency. The aim of this study was to assess and estimate the effect of vitamin A supplementation (VAS) on iron status biomarkers and anemia in humans. Six databases, including Cochrane, EMBASE, LILACS, Pubmed, Scopus and Web of Science, were searched for clinical trials and cohort studies that investigated the effect of vitamin A supplementation alone on iron status and anemia, without time-restriction. The search yielded 23 eligible studies, 21 clinical trials and 2 cohort studies, with children, teenagers, pregnant or lactating women. The meta-analysis of the clinical trials showed that VAS reduces the risk of anemia by 26% and raises hemoglobin levels, compared to non-treated group, independent of the life stage. VAS did not alter the prevalence of iron deficiency among the clinical trials conducted with children and teenagers (RR 0.82, 95% CI 0.60 to 1.12, p = 0.204), whereas a significant increase in serum ferritin levels was observed in trials conducted with pregnant and lactating women (WMD 6.61 μg/L; 95% CI 6.00 to 7.21 μg/L; p < 0.001). Therefore, vitamin A supplementation alone may reduce the risk of anemia, by improving hemoglobin and ferritin levels in individuals with low serum retinol levels.

The In Ovo Feeding Administration (Gallus Gallus)—An Emerging In Vivo Approach to Assess Bioactive Compounds with Potential Nutritional Benefits

“…Iron is a vital trace element for most life forms, and plays an important role in human health. Iron contributes to numerous biologic processes such as oxygen transport, DNA biosynthesis, and energy metabolism [ 59 , 60 , 61 ]. However, iron deficiency is the most common nutrient deficiency; it affects about two billion people worldwide [ 62 ].…”

Vitamin A Requirements in Pregnancy and Lactation

“…Authors of this review also concluded through meta-analysis that antenatal VAS can reduce the risk of maternal anemia (RR: 0.64; 95% CI: 0.43, 0.94), although in comparing the effect of micronutrients that did or did not include VA, the addition of VA to micronutrients did not improve protection against maternal anemia (RR: 0.86; 95% CI: 0.68, 1.09) ( 99 ). Another systematic review found that ferritin was increased in pregnant and lactating women with VAS ( 112 ). This was echoed in an additional randomized trial that identified an association between low serum retinol and maternal anemia (<0.70 µmol/L compared with >1.05 µmol/L; OR: 2.45; 95% CI: 1.44, 4.17), identifying VAD as a potential risk factor ( 113 ), and a case-control study of anemia in pregnant women, in which low VA led to increased anemia (adjusted OR: 8.38; 95% CI: 1.99, 35.30) ( 114 ).…”

Retinol and α‐tocopherol in pregnancy: Establishment of reference intervals and associations with CBC

“…Our results are consistent with the previous reports on retinol levels and anaemia (Semba & Bloem, ; Wang et al, ). A previous report suggests that retinol supplementation may enhance erythropoietin expression and iron mobilization for erythropoiesis in order to improve haemoglobin level (da Cunha, Campos Hankins, & Arruda, ). However, no significant association was observed between α‐tocopherol level and anaemia.…”