The way to someone’s heart may be through their stomach. But it also may be through their tongue, pancreas, fat cells, and thyroid. Alluring, right?
A new review published in the New England Journal of Medicine reassesses how human tongues and tastebuds work, concluding that much of what we know about taste mapping is incorrect, and there’s still much to discover about how tongues function.
That map of the tongue you may have learned in school? Incorrect. While the tongue was previously thought to have different areas that pick up more strongly on different tastes — sweet, sour, salty, bitter — it’s merely a myth. One that’s been disproven for decades, but still, somehow persists in human collective knowledge?
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While the tip of the tongue is said to pick up on sweet flavors, you can lick a pretzel and taste salt or lick a lemon and taste sour. The tongue diagram that originated in 1901 is far from accurate and there’s so much more to how humans perceive what goes in our mouths. The tip of the tongue is dense with sweet receptors, but can certainly taste other flavors as well.
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Recent research by Dr. Josephine M. Egan, M.D., shows that taste receptors extend far beyond the mouth. In fact, in her review titled “Physiological Integration of Taste and Metabolism,” she proves that taste receptors are active far beyond the tongue and exist throughout the body: in the gastrointestinal tract, liver, pancreas, fat cells, brain, muscle cells, thyroid, and lungs. It’s a complex system that can connect to cravings, digestion, nutritional intake, and more.
Taste is also unique to preference. While evolutionarily taste can guide us away from certain flavors, in contemporary times, taste is often linked to preference and culture.
“Our sense of taste is essential not only for experiencing pleasure when we eat but also to help guide us in choosing foods that are safe and won’t harm us,” explains oncology dietitian Meghan Garrity, MS, RDN, CSO. “For instance, humans have evolved to be drawn towards sweeter flavors because sweeter foods tend to be safe and provide calories and nutrients, whereas bitter flavors are less favorable because they were associated with bad or poisonous foods.”
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Western diets, typically high in fat and carbohydrates, can change the tongue’s landscape, and research shows that diabetic mice and their offspring show an increased preference for sweet tastes. This preference can be linked to the taste receptors on the mice’s tongue, as well as their brain, gut, and beyond.
“Current observations suggest that obesity is related to disruptions in the neural pathways that encourage reward-related eating and suppress homeostatic feedback that curbs hunger, although we have yet to fully elucidate the precise physiological mechanisms,” Dr. Egan writes. “However, a direct connection between obesity and taste perception in humans is not proven.” Some studies show that those with a propensity for obesity have higher sweetness thresholds, while other studies can’t find a link between obesity and taste.
There’s still plenty more to understand about taste, but further research can help with medical comprehension and management of illnesses, including obesity and diabetes. For example, if researchers are able to find a taste receptor for fat, that may help cure nutrition-related diseases.
“Research is revealing that our taste receptor cells are much more complex than previously thought. Taste receptors are highly integrated with our central nervous system which directly impacts hormone production. These hormones affect the part of our brain that causes us to feel full or satiated,” says Garrity. “This is important because it can help guide healthcare providers when making recommendations about diet for purposes of weight management. In addition, research has shown us that what we eat on a regular basis actually changes our taste perceptions. By eating a diet that is high in fat and sugar, we will find these foods more palatable. In understanding this, healthcare providers can help support those individuals who are trying to acquire a taste for more nutritious foods.”
This aligns with Dr. Egan’s conclusion that ongoing research can help update dietary guidelines and clinical practice guidelines for what foods make up an ideal diet, and how taste can guide us to better overall health.
