Abstract
An obesity epidemic is spreading rapidly across the world, especially in children. It constitutes a major risk in serious diet-related chronic diseases, thus decreasing life expectancy. The origin of the obesity epidemic is clearly dependent on multiple parameters. Increased consumption of more energy-dense, nutrient-poor foods might be a contributory factor to the epidemic. Behavioural experiments in rats and mice show that both have a spontaneous preference for fatty foods. This lipid attraction is so strong that a mouse with free access to a source of oil in addition to standard laboratory chow becomes rapidly obese. In humans, studies also report that obese subjects have a greater preference than lean subjects for lipids. This last observation suggests that an inappropriate lipid perception might influence obesity risk by impacting feeding behaviour. Why we like fatty foods is not yet fully understood. Recent data demonstrate that low quantities of long-chain fatty acids can be specifically detected in the oral cavity by humans and laboratory rodents. Interestingly, lipid sensors have been found in rodent taste buds, suggesting that gustation can also play a role in the orosensory perception of lipids in combination with textural and olfactory cues. The sense of taste informs the organism about the quality of ingested food. It encompasses five sub-modalities: allowing the perception of sweet, salt, sour, bitter and umami stimuli. The discovery of lipid sensors raises the possibility for a sixth taste modality ('fatty') directed to dietary fat detection. This mini-review highlights recent findings in this new field of investigation in both rodents and humans.