Scientists Hope to Better the Bitter
Find substances that activate receptors on tongue
MONDAY, Oct. 14, 2002 (HealthDayNews) -- A natural aversion to bitter taste can save people from swallowing toxic substances, but some bitter things may actually be healthy.
That's why researchers are trying to figure out how they can trick bitter taste receptors. If they're successful, people might be able to benefit from bitter foods or medications that are currently unpalatable.
While other researchers have already identified the receptor genes for bitter taste, German scientists report in tomorrow's issue of Nature Genetics that they have discovered which substances activate some of the bitter taste receptors.
One of the substances they located a receptor for is known as salicin. This bitter-tasting substance is derived from the bark of the willow tree and is used to control pain, but it also may reduce the risk of heart disease and some cancers because it contains phytonutrients, which are disease-fighting components found in some plants. The active ingredient in aspirin is a cousin of salicin.
"Some [phytonutrients] are healthy, but rejected by the consumer and therefore removed from plant food by breeding and during food processing," says study author Wolfgang Meyerhof, who heads the department of molecular genetics at the German Institute of Human Nutrition. "If their bitter taste can be masked, functional food with high phytonutrient content would probably be attractive to the consumer."
Every human taste bud contains 50 to 100 taste receptor cells, and most people have tens of thousands of taste buds. The four main tastes that receptors can distinguish are salty, sweet, sour and bitter. According to Meyerhof, humans only have 24 bitter taste receptors to perceive thousands of different bitter substances.
Meyerhof and his colleagues were able to find several substances that activate some of these bitter taste receptors. Next, they worked on desensitizing the receptor that perceives the taste of salicin, so that it would become tolerable to ingest. They did this in both lab and human tests by exposing the salicin receptor to a different bitter-tasting compound. For the human tests, volunteers had to keep a bitter tasting solution in their mouths for 15 to 180 seconds.
"The researchers learned what the receptor responds to, and by manipulating it they may be in a position to get around the dilemma of making these phytonutrients palatable," explains Dr. Duane Superneau, chief of the section of medical genetic at the Ochsner Clinic Foundation in New Orleans.
The desensitization of the receptor is only temporary, and gradually it regains its ability to perceive salicin, Meyerhof says.
Besides letting people eat a greater variety of foods with phytonutrients, Meyerhof says desensitizing these receptors might make it easier for people to take some bitter medications.
What To Do
For more information about the discovery of taste receptors, read this article from the National Institute of Dental and Craniofacial Research. To read a primer on the sense of taste, visit the Scientific American.