The Sodium Priority Hypothesis: A Conceptual Taste-Nutrition Framework Linking Salt Taste, Umami and Food Acceptance.

Taste contributes to food selection by integrating sensory information with physiological state and prior experience. Sodium is essential, continually lost, and homeostatically regulated, yet it is abundant and frequently overconsumed in contemporary food environments. This conceptual narrative review proposes the Sodium Priority Hypothesis, as follows: sodium may function as a nutritional target whose acquisition and food acceptance are supported by several partly independent sensory routes. Sodium chloride provides the dominant dietary route to saltiness, although the molecular basis of human salt taste remains unresolved and may involve both sodium- and chloride-dependent mechanisms. Sodium salts can also suppress bitterness and modify taste mixtures in concentration- and matrix-dependent ways. A further, more speculative proposition is that sodium-bearing umami stimuli may have behavioural relevance beyond glutamate-derived umami quality. The framework is intended to connect two timescales: the physiological and evolutionary pressures that promoted sodium acquisition when availability was variable, and the contemporary food environment, in which abundant, inexpensive sodium is widely used to enhance food palatability. It does not claim that sodium alone explains modern excess intake, that prehistoric populations routinely added salt, or that sodium is required for activation of umami receptors. Evidence is strongest for sodium physiology, sodium appetite, salt taste, and selected mixture effects; direct evidence for a sodium-specific contribution to umami liking or intake remains limited. The hypothesis is therefore an organising and falsifiable framework that requires experimental validation. It is explanatory rather than prescriptive.