Effects of subclinical vitamin a deficiency and administration of vitamin a as a single large dose on immune function in children

Majority of the poor children in developing countries suffer from subclinical vitamin A deficiency. It is believed that such children suffer from increased incidence of infections and could be benefitted by administration of large doses of vitamin A. One hundred and twenty three children were investigated and various factors of immunological mechanisms were compared between the groups of children with and without vitamin A deficiency. The effects of administration of 100,000 or 200,000 IU of oral vitamin A were also studied. The neutrophil function as assessed by Hydrogen peroxide (H 2O 2) and superoxide (O − 2) production, antibody response to diphtheria and tetanus antigens, T lymphocyte number and secretory I gA (S IgA) of saliva were determined. The results indicated that the neutrophil functions, antibody response and salivary S IgA were comparable between the two groups of children while the T cell number was significantly low in deficient children. Administration of vitamin A produced an increase in H 2O 2 production without any significant changes in O − 2 generation. Antibody responses were comparable with that of the controls. However, S IgA levels were the groups of children receiving the different dosage schedules. The observations suggest that mechanisms other than immune function could be involved to a greater extent in increasing the susceptibility of children with subclinical vitamin A deficiency to infections. As the effects on the immune system were similar between 100,000 IU or 200,000 IU, it is speculated that doses smaller than 100,000 IU could bring about more uniform effects.