Impact of vitamin A supplementation on anaemia and plasma erythropoietin concentrations in pregnant women: a controlled clinical trial

INTRODUCTION: Although studies suggest that vitamin A or its metabolites influence the synthesis of erythropoietin in vitro and in animal models, it is unclear whether vitamin A supplementation increases plasma erythropoietin concentrations in humans. OBJECTIVE: To determine whether daily vitamin A supplementation increases plasma erythropoietin concentrations in pregnant women with a high prevalence of anaemia. METHODS: A randomized, double-blind, controlled clinical trial was conducted to examine the effect of daily vitamin A (3000 microg retinol equivalent), iron (30 mg), and folate (400 microg) versus iron (30 mg) and folate (400 microg) (control) on haemoglobin and plasma erythropoietin concentrations in 203 pregnant women in Malawi, Africa. RESULTS: Mean gestational age at enrollment was 23 wk, at which time 50% of the women were anaemic (haemoglobin <110 g/L). Mean (+/-SEM) change in haemoglobin from enrollment to 38 wk was 4.7+/-1.6 g/L (p=0.003) and 7.3+/-2.3 g/L (p=0.003) in the vitamin A and control groups, respectively. Mean change in plasma erythropoietin concentrations from enrollment to 38 wk was 2.39+/-5.00 (p=0.63) and -2.87+/-3.92 IU/L (p=0.46) in the vitamin A and controls groups, respectively. There were no significant differences between vitamin A and control groups in the slope of the regression line between log10 erythropoietin and haemoglobin at enrollment or 38 wk, and between enrollment and follow-up within either group. CONCLUSIONS: Vitamin A supplementation does not appear to increase haemoglobin and plasma erythropoietin concentrations among pregnant women with a high prevalence of anaemia in Malawi.