Salt conditions a flavor preference or aversion after exercise depending on NaCl dose and sweat loss

Sodium supplementation during or after exertion improves hydration. We hypothesized that it may therefore improve well being after exercise-induced sodium loss. To avoid cognitive-biased interpretations of the taste of salt, we used untasted salt in swallowed capsules to condition preference for the flavor of a drink. In four 90 min exercise sessions, 2-3 days apart, participants drank 100 ml of a novel drink and swallowed a capsule, either empty (placebo), or containing 200, 400 or 600 mg NaCl (n=20 in each group). We found both increases and decreases in flavor preference conditioning, depending on salt dose and level of sweat loss: in groups receiving salt supplementation, high levels of sweat loss induced greater flavor conditioning of preference than low levels of sweating. However, 600 mg NaCl conditioned a flavor aversion relative to placebo, which was greater in exercisers sweating little. We conclude that since untasted salt conditioned flavor preference in direct proportion to the amount of sweat lost, replenishment of the sodium lost in sweat induces a rewarding physiological state. The results provide further evidence for the physiological determinants of human salt appetite, and buttress the evidence that post-ingestive effects condition food preferences. Conditioned flavor preference may also provide a useful measure of the benefits of other nutrient additives in sports drinks.