Vitamin A is a fat soluble vitamin and essential nutrient that exists in several forms both in animal foods (as retinol, retinal or retinoic acid) and plant foods (as carotenoids). Good sources of vitamin A are meat, fish, poultry, and dairy foods such as milk, cheese and yoghurt. Carotenoids can also be found in dark green and yellow/orange fruits and vegetables.

Micronutrients in general, including vitamin A, play essential roles in maintaining immune function (1,2,3). Vitamin A is important for sight (especially night adaptation and vision), immunity, growth and development, and red blood cell production (4,5,6). It plays a central role in the development and differentiation of white blood cells, such as lymphocytes, which are essential for immune response (7). The body’s first line of defence against infection is provided by the skin and mucosa, the integrity of which is maintained by vitamin A.

Low micronutrient levels are common in HIV-infected adults, particularly in developing countries where diets are often poor. HIV is known to have an impact on nutrient intake, absorption, metabolism and storage. Micronutrient deficiency and HIV both have an impact on immune function. Low levels of vitamin A in the blood are associated with rapid HIV disease progression and death (8–10). For this reason there has been much interest in micronutrient supplementation and its possible role in improving immune function, preventing HIV transmission (especially to children) and delaying HIV disease progression.

Vitamin A supplementation has been shown to correct deficiency in malnourished HIV-infected individuals but it is unclear how much this contributes to restoring immune function. A meta-analysis examining the effect of vitamin A or multiple micronutrient supplementation trials in HIV-infected adults and children found no conclusive evidence that vitamin A supplements improved CD4 counts or delayed HIV disease progression. Although vitamin A supplementation in HIV-infected pregnant women was associated with reduced anaemia (11), vitamin A supplements have not otherwise been found to reduce morbidity and mortality in HIV-infected adults. In HIV-infected children however, there is consistent evidence that vitamin A supplements given either as periodic or daily supplements reduces diarrhoea, cough, pneumonia and all-cause mortality (12).

Malnutrition, infection and immune competence are synergistically related. Infectious diseases influence nutritional status and conversely almost any nutrient deficiency, if severe enough, can impair the body's resistance to infection (13–16). Good nutrition is therefore essential in HIV/AIDS management, especially in poorer populations. Many areas with high HIV prevalence are also likely to have poor access to health services and antiretroviral therapy (ART), and are likely to have a poor dietary intake and a higher prevalence of malnutrition and poverty. In such situations, efforts to improve nutritional status would complement antiretroviral therapy, and WHO is currently developing guidelines for the nutritional care and support of adults and adolescents living with HIV.

References

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4. Solomons NW. Vitamin A and carotenoids. In: Bowman BA, Russell RM, eds. Present knowledge in nutrition, 8th ed. Washington D.C., ILSI Press. 2001; 127–45.

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10. Semba RD, Graham NM, Caiaffa WT, Margolick JB, Clement L, Vlahov D. Increased mortality associated with vitamin A deficiency during human immunodeficiency virus type 1 infection. Archives of Internal Medicine. 1993; 153(18):2149–54.

11. Irlam JH, Visser MM, Rollins NN, Siegfried N. Micronutrient supplementation in children and adults with HIV infection. Cochrane Database of Systematic Reviews. 2010; (12):CD003650.

12. Fawzi WW, Msamanga GI, Kupka R, Spiegelman D, Villamor E, Mugusi F, et al. Multivitamin supplementation improves hematologic status in HIV-infected women and their children in Tanzania. American Journal of Clinical Nutrition. 2007; 85(5):1335–43.

13. WHO. Scrimshaw NS, Taylor CE, Gordon AJE. Interactions of nutrition and infection. WHO monograph series no.57. Geneva: World Health Organization; 1968. (http://whqlibdoc.who.int/monograph/WHO_MONO_57_(part1).pdf)

14. Scrimshaw NS, Taylor CE, Gordon JE. Interactions of nutrition and infection. American Journal of Medical Science. 1959; 237:367–403.

15. Scrimshaw NS, SanGiovanni JP. Synergism of nutrition, infection, and immunity: an overview. American Journal of Clinical Nutrition. 1997; 66(2):464S–477S.

16. Chandra RK. Nutrition as a critical determinant in susceptibility to infection. World Review of Nutrition and Diet. 1976; 25:166–88.

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Conflict of interest statements were collected from all named authors and no conflicts were identified.