Assessing immune function changes in exercise and diet intervention studies

To discuss the advantages and limitations of the methods currently available to assess changes in human immune function in response to interventions such as changes in diet or exercise.

Much recent research has focused on the effect of regular moderate exercise and the role of foods or specific food components in enhancing immune system responsiveness to challenge and thereby improving health and reducing disease risk. The present review summarizes the issues in experimental design that need to be considered in human intervention studies, the immune function variables commonly used as markers in such studies and the biological relevance (e.g. known correlation with clinically relevant endpoints) of the markers. In-vivo markers appear to be the best. Markers of peripheral blood leukocyte function are also of value since they may provide information on the mechanism(s) of change caused by an intervention.

Currently, no single marker of human immune function is available to predict the outcome of an exercise or dietary intervention on the resistance to infection or to other immune system-related diseases. There is too little evidence at present that correlates individual markers with global health improvement and therefore assessing changes of immune function requires a thorough methodological approach targeting a large spectrum of parameters.