Obesity is a growing problem worldwide, but questions remains about its effects on our bodies. In a new PLOS Biology study, Robin Dando, assistant professor in the Department of Food Science at Cornell University, investigated how obesity in mice might lead to a reduced sense of taste. I interviewed Dando via email to find out more.
What led you to study food science?
RD: I have an unusual background for a food science researcher. My degrees are in physics, but after my Ph.D. I trained in physiology and worked on our sense of taste. Although I work in a food science department, I joke that I’m more interested in the people consuming food than the food itself! These days, we spend so much of our time and money on food that I think studying how our bodies respond to what we eat is fascinating, and has profound consequences for global health.
Tell us a little about the mammalian taste system – how does taste work?
RD: Taste works in concert with our other senses to give us information about the food we’re about to ingest. Taste evolved to enable our survival by helping us consume more of what we need, and less of what we don’t. When things taste good, they likely contain calories, minerals or protein, which all help us survive. If things taste bad to us, it could be because they have spoiled or because they contain something toxic.
In your study, you examined the effect of obesity on taste buds in mice. How did you go about this?
RD: We used litters of mice so they would be as genetically similar to each other as possible. We put half of the siblings on a normal, healthy diet, and the other half on a high-fat diet that induces obesity over just eight weeks. We then examined the morphology of the taste buds of both groups, as well as the expression of markers important for taste and for inflammation.
What effect did you find?
RD: Simply put, we found that mice that gain excess weight end up with many fewer taste buds than mice that stay a healthy weight. These obese mice are likely to perceive less when consuming food, and we believe this could change their feeding behavior; loss of taste may lead to overconsumption. I think our findings may offer a new explanation for why obese people can make poor food choices.
What did you learn about the mechanism leading to a reduction in taste buds?
RD: We found that taste tissues were undergoing more apoptosis (programmed cell death) in obese mice than in lean mice. Obese mice also had fewer of the progenitor cells responsible for making new taste cells. Further investigation suggested that the loss of taste buds is a consequence of the inflammation that results from obesity rather than the presence of fat itself; in mice that don’t become so obese on the high-fat diet, and so don’t experience most of the effects of inflammation, we saw no loss of taste despite the high-fat diet. We also found that the protein TNFα, which is strongly linked to both obesity and apoptosis, appears to be key in triggering the obesity-related reduction in taste.
What are the next steps for your research?
RD: I’d like to investigate just how much losing taste input changes feeding behavior. For example, in a paper we published last year, we found that humans desired higher-calorie stimuli when we temporarily blocked their sense of taste. I’d also like to research if loss of taste is reversible with weight loss. In future, research might suggest a way to protect taste buds during weight gain, which could help obese people to make healthier food choices.
Research Article: Kaufman A, Choo E, Koh A, Dando R (2018) Inflammation arising from obesity reduces taste bud abundance and inhibits renewal. PLoS Biol 16(3): e2001959. https://doi.org/10.1371/journal.pbio.2001959
Images Credits: Alexas Fotos, Pixabay; Robin Dando