Exercise increases the preference for salt in humans

Salt preference was evaluated in 21 male students before and after 1 h routine exercise by measuring their preferred concentration of NaCl in tomato soup. Before exercise, baseline measures of preference were similar to those of 21 matched student controls that did not exercise. Immediately after exercise, the amount of NaCl added to flavour the soup increased by approximately 50% in comparison to pre-exercise baselines and to non-exercising controls. Concentration of sugar flavouring tea was unaltered. Twelve hours after exercise, preferred concentrations of both salt in soup and of sugar in tea were elevated. There were no changes, at any of these time intervals, in the preferences of the control students that did not exercise. These delayed and non-specific changes in preferences are attributed to hunger. However, we speculate that the immediate and specific increase in NaCl preference after exercise is due to sodium loss (in perspiration) and/or sympathetic arousal that activates the hormones, aldosterone and angiotensin II in humans, and that in animals increases salt preference. Our findings provide further evidence for the physiological regulation of salt preference in humans.