Immune responses during recovery from protein-energy malnutrition.

Protein-energy malnutrition (PEM) is a worldwide problem. Infants and children from developing countries and elderly people from all around the world are the two main groups suffering from PEM. PEM induces profound immunodeficiency, characterized mainly by decreased cell-mediated immunity, and also by decreased humoral and non-specific immunity. Non-specific immune deficiency is of particular importance for defences against infections and its decrease in PEM may further deteriorate nutritional and immune status, pushing patients into a vicious and dramatic circle. Refeeding such patients and the restoration of their nutritional status lead to improvement in all immune responses: a strong association between the evolution of these two responses is always observed during refeeding. The need for specific nutrients to restore immune functions during refeeding of PEM patient has been extensively studied in the past years. This review describes the pathophysiological mechanisms of immune consequences of PEM and of immune restoration with refeeding, and in addition focuses upon some nutrients of particular importance, namely glutamine, zinc and vitamin E. Particular attention is directed at the elderly patients with PEM, a growing population for which the importance of undernutrition on prognosis is not yet fully recognized.