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Scientists savor a new area of research. Evidence shows that the sense of taste is more complex than previously believed. One set of findings suggests that humans inherit different levels of tasting ability. These levels may influence food preferences and, in turn, health status.
Drano for dinner? Maybe some dishwashing detergent for dessert?
For years researchers have known that our brain's ability to recognize tastes with the tongue helps deter us from eating poison.
Accumulating evidence now suggests that this taste detection system varies in sensitivity between individuals and also may infiuence our daily diet. Scientists are finding that people inherit different levels of responsiveness to a particular test chemical. Some can't taste it, while others, dubbed supertasters, compare it to an extremely bitter concoction such as stomach bile. It's gross. It turns out that supertasters tend to find many tastes more intense than other people do.
This research is leading to:
- A clearer understanding of the function of the sense of taste.
- Insight on how taste ability relates to picky eating and possibly health status.
Scientists are just beginning to understand the complexity of the sense of taste. It's known that after a few crunches, the spit in your mouth breaks down a wedge of pizza into particles. The molecular crumbs contact the taste buds, which cover the tongue. Studies show that many different interactions take place depending on whether the morsel is of a sweet, sour, salty or bitter origin. In the end, nerve fibers send taste signals to taste centers in the brain.
In addition to the basic tastes of sweet, sour, salty and bitter, some researchers say studies show that a meatlike taste, known as umami, exists. Other scientists, however, believe more research is needed to determine if umami is a completely separate basic taste category. A recent finding indicates that specific structures on taste buds detect molecules of glutamate, which produce the umami quality.
While many researchers continue to map the molecular underpinnings of taste perception, others are investigating the "broccoli dilemma." Why do some hate it and some love it? Scientists are finding that we inherit a level of tasting ability that appears to infiuence what we eat.
The first indication that taste varied between individuals was found in 1931. A chemist discovered that a particular molecule was undetectable to some and bittertasting to others. In 1932, researchers found that the reaction to the chemical ran in families.
Since then researchers have found evidence that approximately 25 percent of people are supertasters and find the synthetic compound, propylthiouracil (PROP), intensely bitter. Some 50 percent find it moderately bitter; about 25 percent can't taste it at all.
Supertasters may experience an overall higher level of tasting ability than others, according to some evidence. For example, they have a greater number of the structures that often hold the taste buds (see illustration). In addition, supertasters appear to be more responsive to many bitter compounds, including those in coffee, grapefruit juice and green tea. Supertasters perceive saccharin and sucrose as sweeter than other people do. They also seem to be more sensitive to oral pain. The burning heat set off by the chili pepper ingredient, capsaicin, is more intense in supertasters than in others.
Scientists plan to investigate how these findings translate into food preferences and influence health. For example, supertasters may face a higher risk of cancer if they find broccoli and other veggies that carry cancer-preventing vitamins too bitter to stomach. On the other hand, a supertaster's discriminating palate may mean a lower risk of becoming overweight, an alcoholic or a smoker.
Currently researchers are analyzing the genetic makeup of families in order to locate the gene that is associated with PROP tasting.
Researchers have found that, compared to others, supertasters have a greater number of structures that often house taste buds. These pin-head-sized structures, known as fungiform papiliae, can be detected by dabbing some blue food coloring on your tongue. The fungiform papi11ae will remain pink while the rest of the tongue will stain blue.
Photos courtesy of Linda Bartoshuk, Ph.D. Yale. Illustration by Lydia Kibiuk.