Essential nutrients and immunologic functions.

Several indexes of immune response, including responses on delayed-type hypersensitivity skin tests, antibody production, lymphocyte proliferation, cytokine production, and numbers of the specific subgroups of white blood cells, are influenced by essential nutrient intake and may serve as functional tests for evaluating nutritional status. In certain segments of the population, such as elderly persons and smokers, activity of the immune indexes can be increased through dietary supplementation with micronutrients, and there may be a rationale to increase selected recommended dietary allowances for the general population. The activity of the immune system may also be enhanced with decreases in total fat intake or lessened with increases in total fat intake, particularly of the n-3 type. Research to date, therefore, suggests that several dietary components, both essential and nonessential, can affect human immune response. The intake of these nutrients can be modulated to regulate the activity of the immune system.