A group of American researchers found that obese mice have 25% less taste buds in the tongue than healthy rodents, according to a study published today in the journal PLOS Biology.
Previous reports have suggested that weight gain can reduce the sensitivity of the sense of taste and that this effect can be reversed when the weight is lost again, but until now it was not clear how this phenomenon occurs.
A gustatory papilla is composed of approximately 50 to 100 cells of three main types, each with different roles in the detection of the five main flavors: salty, sweet, bitter, acidic and umami.
To explore changes of taste buds due to obesity, the authors fed a group of mice with a normal diet composed of 14% fat and another with a diet containing 58% fat. As expected, after eight weeks, the mice fed the fatter diet weighed about a third more than those fed normal food. According to the researchers, these results could point to new therapeutic strategies to alleviate taste dysfunction in obese people.
But surprisingly, according to the biologists at Cornell University in New York (United States), the obese mice had 25% less taste buds than the thin rodents, with no change in the average size or distribution of the three cell types.
The renewal of the cells of the gustatory papilla, which occurs every 10 days, usually arises from a balanced combination of programmed cell death – a process known as apoptosis – and the generation of new cells from special progenitor cells. However, the researchers observed that the rate of apoptosis increased in the obese mice, while the number of progenitor cells of the sense of taste in the tongue decreased, which probably explains the net decrease in the number of taste buds.
On the other hand, rodents that are genetically resistant to obesity did not show these effects, even when they were fed a diet high in fat, which implies that the loss of taste buds is not due to fat consumption per se, but to the accumulation of adipose tissue.
“These data together suggest that gross adiposity stemming from chronic exposure to a high-fat diet is associated with a low-grade inflammatory response causing a disruption in the balancing mechanisms of taste bud maintenance and renewal,” Robin Dando, one of the researchers explained. “These results may point to novel therapeutic strategies for alleviating taste dysfunction in obese populations.”