Prevalence Of Vitamin A Deficiency In Critically Ill Children With Sepsis And Its Association With Clinical Outcomes

Vitamin A plays an essential role in a large number of physiological functions that encompass vision, growth, reproduction, hematopoiesis, and immunity.

Despite major advances in the knowledge of vitamin A biology, its deficiency is still a serious public health problem that affects an estimated 127 million preschool children. In children, vitamin A deficiency results in increased risks of mortality and morbidity from infections, blindness and anemia. Many of these effects can be linked to the immunological functions of vitamin A.

Vitamin A modulates immunity through its active metabolite retinoic acid (RA), which acts on retinoid receptors in various cell types. Studies utilizing various animal models of vitamin A or retinoid receptor deficiency have revealed an integral role for RA in immunity and tolerance.

Retinoic acid (RA) has been reported to promote anti-inflammatory regulatory T cell (Treg) differentiation and inhibit interleukin (IL)-6-induced proinflammatory T helper 17 (Th17) cells, which could balance pro- and anti-inflammatory immunity.

Vitamin A deficiency (VAD ) is associated with adverse health outcomes due to an increased risk of infection in children. VAD could impact immunity at multiple levels, including disturbing the integrity of the gastrointestinal mucosal barrier, decreasing monocyte and natural killer (NK) cell numbers, and impairing the function of macrophages, dendritic cells, and neutrophils.