An important new study from researchers at Cornell University has found that when mice become obese they can also lose up to 25 percent of their taste buds. This connection between obesity and taste has previously been observed in humans, but this is the first research to potentially uncover a biological explanation behind the phenomenon.
A few years ago John Morton from the Stanford University School of Medicine presented some research, inspired by his clinical practice, finding obese patients reported an increase in taste sensitivity following bariatric surgery. Morton's study found 87 percent of patients reported a change in how food tastes following the surgery, but at the time there was no evidence to suggest that there was any fundamental anatomical change occurring.
Now new research conducted on mice is suggesting that weight gain causes an inflammatory response in the body that results in a significant decline in the volume of taste buds. The lifespan of a taste bud is relatively short – around 10 days. In the mouse models it was found that the number of taste bud progenitor cells declined in conjunction with a high-fat diet leading to obesity. This meant that the normal renewal process for taste buds was notably disrupted by weight gain.
"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," says Robin Dando, senior author on the research.
Further research revealed the mechanism behind this taste bud change stemmed from an increase in a pro-inflammatory cytokine called TNF-alpha. When mice engineered to not produce TNF-alpha were fed high-fat diets they were found to have no reduction in taste bud production despite becoming obese. And when TNF-alpha was administered directly into the tongue of healthy, lean mice, a direct decrease in taste buds was identified.
The hypothesis, if this same mechanism is also occurring in humans, would be that obesity results in a spiraling cycle that reduces a person's sensitivity to taste leading to them seeking out more intense, rich flavors. This would mean favoring foods with more sugar, salt, and fat – the golden triangle of fast food.
The good news is that this process is potentially reversible with Dando suggesting that "this is a two-way mechanism." The researcher's note this discovery should pave the way for new obesity treatments that can target this dysfunction in taste bud production.
The new research was published in the journal PLOS Biology.