Scientists from the Monell Center have reported that functional olfactory receptors, the sensors that detect odors in the nose, are also present in human taste cells found on the tongue. The findings suggest that interactions between the senses of smell and taste, the primary components of food flavor, may begin on the tongue and not in the brain, as previously thought.
“Our research may help explain how odor molecules modulate taste perception,” said study senior author Mehmet Hakan Ozdener, a cell biologist at Monell. “This may lead to the development of odor-based taste modifiers that can help combat the excess salt, sugar, and fat intake associated with diet-related diseases such as obesity and diabetes.”
While many people equate flavor with taste, the distinctive flavor of most foods and drinks comes more from smell than it does from taste. Taste, which detects sweet, salty, sour, bitter, and umami molecules on the tongue, evolved as a gatekeeper to evaluate the nutrient value and potential toxicity of what we put in our mouths. Smell provides detailed information about the quality of food flavor, for example, is that banana, licorice, or cherry? The brain combines input from taste, smell, and other senses to create the multimodal sensation of flavor.
Until now, taste and smell were considered to be independent sensory systems that did not interact until their respective information reached the brain. In the study, published in Chemical Senses, Ozdener and colleagues used methods developed at Monell to maintain living human taste cells in culture. Using genetic and biochemical methods to probe the taste cell cultures, the researchers found that the human taste cells contain many key molecules known to be present in olfactory receptors.
They next used a method known as calcium imaging to show that the cultured taste cells respond to odor molecules in a manner similar to olfactory receptor cells. Together, the findings provide the first demonstration of functional olfactory receptors in human taste cells, suggesting that olfactory receptors may play a role in the taste system by interacting with taste receptor cells on the tongue.