Humans show markedly higher preference for foods rich in fat and a lower preference for high-sugar foods when they have mutations in a specific receptor found in the brain, compared with people without these mutations, reports a study published online in Nature Communications. These results suggest that a defined neuronal circuit may mediate food preference in humans.
Hypothalamic and brainstem neuronal circuits are critically involved in the regulation of feeding behavior. Previous extensive work in mice has shown that disruption of melanocortin signaling through mutations in the gene for the melanocortin-4 receptor (MC4R) leads to over-consumption of food, increased preference for fat rich foods and lower preference for sugar. However, the relevance of these findings to regulation of eating behaviour in humans has been unclear.
Ismaa Farooqi and colleagues tested the food preferences of up to 14 individuals with rare variations in MC4R that led to deficiency in melanocortin signaling and compared them with lean and obese individuals. Individuals were free to choose between three food options that had similar ‘liking’ ratings in terms of appearance, texture and taste but contained either low, medium or high levels of fat. The participants did not know these differences in fat content and also did not mention such differences in post interviews. People with MC4R mutations consumed 95% and 65% more of the high-fat meal compared to the lean and obese control groups (respectively). On the other hand, the preference for desserts with high sugar content was significantly lower in the MC4R-mutated individuals.
These findings provide initial confirmatory evidence in humans for the role of MC4R in food preferences and suggest a direct association between melanocortical signalling in specific neuronal circuits and preference for different food types.