Obesity reduces taste bud numbers in mice

Cornell University researchers attempting to prove a theory that overeating can affect people’s sense of taste have found that obesity can reduce the number of taste buds in mice.

The team placed laboratory mice on a high-fat diet, causing rapid weight gain, then counted the number of taste buds on the tongue.  They found mice on the high-fat diet had 25% fewer taste buds than the mice that were kept on a normal diet on an area of the tongue that is usually densely packed with them.

Cornell food scientist Robin Dando said of the findings: “This could be a whole new kind of target in treating obesity. People don’t really look at the taste bud, but it’s so fundamental.”

According to Dando, taste buds regenerate constantly as the 50 to 100 cells die and are replaced by new ones. The lifespan of a taste bud is approximately ten days. It takes four weeks for the entire tongue to regenerate all of its taste buds. The study found that both short-term and long-term taste buds were affected in obese mice, with cell death accelerating and resupply decreasing.

The research team discovered that foods with high-fat content did not affect the production of taste buds. Instead, chronic inflammation in the body caused by obesity could explain the phenomenon.

“Mice were fed a standard lab rodent chow in the control condition, and a high-fat version of this diet in the obese condition,” Dando told Food Processing Technology.

“The taste buds of mice are put together very similarly to those of humans.  While there are some differences in how we perceive certain stimuli, for example some artificial sweeteners, the taste buds of mice utilise a mostly analogous set of receptors, signaling mechanisms and developmental factors as do humans.”

Dando’s team found that mice that were genetically incapable of producing the common inflammatory molecule TNF-alpha became obese but did not lose taste cells. Injecting the molecule into the tongues of lean mice did, however, cause an increased cell death rate.

Stanford University bariatric surgeon Dr John Morton, who wasn’t involved in the research, added: “[The study] does underscore the relationship between taste sensitivity and weight. It’s another reason why it’s hard to lose weight.”

Morton conducted a similar study a number of years ago on his gastric bypass patients, testing their taste perceptions before and after weight loss.

While diet, exercise and genetics are just some of the factors affecting obesity, taste is becoming an important factor. Previous studies have suggested that obese people are less perceptive of flavour than those of normal weight.

Dando co-authored a paper on a previous study in 2017 that tested taste abilities in human males, telling Food Processing Technology: “[The paper] shows that male participants who gained weight over the course of a year of testing lost taste function, when compared to those who stayed the same weight.”