A randomised controlled trial to test equivalence between retinyl palmitate and β carotene for vitamin A deficiency

Abstract

Objectives - To determine whether β carotene is therapeutically equivalent to retinyl palmitate in the formulation currently recommended by the World Health Organisation. Design - Randomised blind equivalence trial. Setting - Rural area in Senegal. Subjects - Children aged 2-15 years suffering from vitamin A deficiency as defined by abnormal results on eye cytology were randomly allocated treatment with retinyl palmitate (n=256) and β carotene (n=254). Main outcome measure - Reversion to normal results on eye cytology as defined by the reappearance of goblet cells and normalisation of the epithelial cells. Results - Seven weeks after the supplement was given the percentages were 51̇2% (124/242) children taking retinyl palmitate and 50̇0% (123/246) of those taking β carotene, who had reverted to normal eye cytology, a difference of 1̇2% (95% confidence interval 0̇8% to 1̇6%). According to an equivalence testing procedure, the two treatments were statistically equivalent; the null hypothesis of non-equivalence was rejected (one tailed p value=0̇03). Conclusions - β Carotene supplementation seems to be a promising candidate for the alleviation of vitamin A deficiency. It could be given either as high dose capsule or through increased dietary intake. The challenge now is to improve dietary intake of vitamin A in programmes that are effective and sustainable at the community level.