Vitamin A supplementation increases ratios of proinflammatory to anti‐inflammatory cytokine responses in pregnancy and lactation

Summary Vitamin A supplementation reduces child mortality in populations at risk of vitamin A deficiency and may also reduce maternal mortality. One possible explanation for this is that vitamin A deficiency is associated with altered immune function and cytokine dysregulation. Vitamin A deficiency in pregnancy may thus compound the pregnancy‐associated bias of cellular immune responses towards Th‐2‐like responses and exacerbate susceptibility to intracellular pathogens. We assessed mitogen and antigen‐induced cytokine responses during pregnancy and lactation in Ghanaian primigravidae receiving either vitamin A supplementation or placebo. This was a double‐blind, randomized, placebo‐controlled trial of weekly vitamin A supplementation in pregnant and lactating women. Pregnancy compared to postpartum was associated with a suppression of cytokine responses, in particular of the proinflammatory cytokines interferon (IFN)‐γ and tumour necrosis factor (TNF)‐α. Mitogen‐induced TNF‐α responses were associated with a decreased risk of peripheral parasitaemia during pregnancy. Furthermore, vitamin A supplementation was significantly associated with an increased ratio of mitogen‐induced proinflammatory cytokine (IFN‐γ) to anti‐inflammatory cytokine (IL‐10) during pregnancy and in the postpartum period. The results of this study indicate that suppression of proinflammatory type 1 immune responses and hence immunity to intracellular infections, resulting from the combined effects of pregnancy and vitamin A deficiency, might be ameliorated by vitamin A supplementation.