The nutrition and fluid requirements of a sportsperson should be tailored not only to the sport, with endurance being the most important variable, but also to the individual competitor and the physical environment at the time of the event. This applies especially to fluid intake. There is agreement that the proportion of carbohydrate in the diet should be high and that of fat low. The evidence for increased metabolic demands for vitamins and minerals (except possibly calcium and iron) in exercise is equivocal. Fluid is still the priority constituent that needs monitoring.