[Mechanisms of dietary selection in man: preferences and aversions]

Ingestion of food and water is the most important mean by which an animal maintains the integrity of the "milieu interne". In a free feeding situation the animal selects the nutrients demanded by the monitors of the internal fluid environment and avoids the malaise caused by ingested toxins; to doing, it maintains the constancy of its body composition. The essential features of this qualitative regulation have been extensively studied in the animal: the choice of nutrient is based on the sensory activity of the ingested material at the oropharynegeal level; some preferences and aversions are innate; others are acquired by conditioning; conditioned taste aversions can be acquired after a single association between the conditioned stimulus (taste) and the unconditioned one (malaise); some preferences and aversions are acquired slowly under the reenforcing effect of the nutritional activity of the ingested food. Are the same characteristics found in man? Studies in man are not numerous but it seems that the same mecanisms are patent in the neonate, the young child and the adult in a distressful situation. On the contrary, in a free feeding situation, sociocultural factors are prevalent.