ABSTRACT
Nutritional status is a condition that determines one of the kinds of existing relationships between nutrition and infection where latter can affect the former and vice versa. Malnutrition is a continuous shortage of certain important nutrients in the diet, particularly vitamins and minerals, resulting to deficiency diseases or infectious diseases due to loss of immune protection. Malnutrition is a known, presumable predisposing factor for infectious diseases that exhibits a synergistic action to further diminish appetite. The involvement of molecular mechanisms underlying nutritional influence on the onset of infectious diseases formed the basis of this review. There exist an appreciable number of nutritional influences on the initiation of infectious disease, with molecular mechanisms underpinning the diminished lymphocytes resulting in immunosuppression. The malnutritional cause of infectious disease could involve the deficiency of vitamins such as vitamin A via shortage of its primary active metabolite, retinoic acid in the intestinal epithelial cells. Protein malnutrition leads to deficiency in biosynthesis of retinol-binding protein by depriving retinal dehydrogenase assess to retinol, restricting its enzymatic action which could provide retinoic acid for antibody secreting cells among other immunological roles. One other mechanism involves antioxidant-deficient food heavily diminishing cell-to-cell communication that is crucial for the immune system to prevent diseases. Also, circulating leptin levels that fall during periods of malnutrition or fasting could, through the leptin receptor (LepR), directly affect CD4+ T lymphocytes, reducing the metabolism and functionality of these cells. Deficiencies in nutrition, indeed, cascades the onset of infectious diseases.
