Nutrition and immunity: an update

Immunity encompasses all mechanisms and responses used by the organism to defend itself against bacteria, viruses or parasites. Adequate supply and balance of nutrients are required for proper efficiency of the host defences. Research has identified dietary factors that affect human and animal immune responses like amino acids, fatty acids, minerals and vitamins. Some of these nutrients have been proven to have specific actions on immunity when provided at pharmacological doses. This paper will review these nutrients and their current use in aquaculture. The immune system is an efficient but complex system. Its complexity has made the assessment of the effects of diets difficult. Nevertheless, the standardization of methodology as well as the use of new techniques at the cell or the gene level should help to better understand the mechanisms of immune modulation. This paper will review the major functions of fish and shrimp immune system and the methodologies used. Cellular and humoral functions including cytokines will be discussed in relation to potential means to modulate them and the underlying mechanism. A better understanding of the mechanisms of modulation of the immune functions should help in the discovery of new dietary factors to improve the immune status of the animal, leading to better disease resistance.