Physical activity and nutrition are important in a healthy lifestyle with potential benefits to immunity often overlooked. Infection of the upper respiratory tract, and the associated symptoms, are the most frequent presentations to general practitioners and may have significant economic and social impact. In this review, we consider the role of physical activity and nutrition in improving immunity. Evidence suggests that regular moderate activity is particularly beneficial for immune enhancement and reducing the risk of infection. We also discuss some nutritional strategies. Unfortunately, the evidence for many is weak. Avoiding nutritional deficiencies seems the most pragmatic recommendation. This can be achieved with a balanced diet. Including a variety of fruits and vegetables may help ensure adequate intake of essential nutrients with little risk of excess intake of any single nutrient. Supplementation with individual nutrients is generally not recommended. Multinutrients may be beneficial for those with a preexisting deficiency but not if normal dietary intake is sufficient. Further benefit may be gained from some supplements including probiotics, bovine colostrum, and some plant-derived products (Echinacea, black elderberry, and some polyphenols) but only in specific situations/contexts. Individuals should consider their personal needs, use caution, and avoid the indiscriminate use of supplements.

14Carbohydrate (CHO) supplementation during prolonged exercise is widely acknowledged to 15 blunt in vitro immunoendocrine responses but no study has investigated in vivo immunity. 16Purpose: To determine the effect of CHO supplementation during prolonged exercise on in 17 vivo immune induction using experimental contact hypersensitivity (CHS) with the novel 18 antigen Diphenylcyclopropenone (DPCP). 19Methods: In a double-blind design, 32 subjects were randomly assigned to 120 minutes of 20 treadmill exercise at 60% ̇O 2max with CHO (Ex-CHO) or placebo (Ex-PLA) 21 supplementation. Responses were also compared to 16 resting control (CON) subjects from a 22 previous study (for additional comparison with a resting non-exercise condition). 23Standardised diets (24 h pre-trial) and breakfasts (3.5 h pre-trial) were provided. Subjects