Rats (Rattus norvegicus) do not prefer salted solid food

Many studies have demonstrated that when sodium-replete rats are given a choice between water and isotonic saline, they consume more of the isotonic saline. Their ingestive responses to a choice between salted and unsalted food, however, have not been studied in the same detail. Because humans consume salt in or on food rather than in pure water, this lack of information calls into question the use of the rat as the animal model for human excess salt consumption. In Experiment 1, 16 Sprague-Dawley rats were given 1-hr access to salted and unsalted foods (potato chips, peanuts, soup) commonly consumed by humans in the salted form. In each choice situation, rats consumed more of the unsalted variety of solid food. In Experiment 2, the concentration of salt in a wider variety of foods was varied. Fifteen rats were allowed a choice of a given salt concentration or the unsalted food. In no case was the salted solid food eaten in excess of the unsalted solid food, and in general, more of the unsalted solid food was eaten. In a third experiment, two groups of 8 rats were given exposure from weaning to either salted or unsalted potato chips. Three-months of exposure to salted chips or unsalted chips did not alter the rats' relative intake of salted chips. When given a choice, more unsalted chips were consumed by both groups. These experiments indicate that sodium-replete Sprague-Dawley rats generally prefer unsalted solid foods to salted ones.