Taste: Genetics of

When any two people taste a food, even simple ones, they will not have the same sensory experience. And the perceptual differences between them will only grow with the complexity of the food they sample, such as with a full course meal served with wine. Biologists, philosophers, and psychologists have discussed this idea related to different species, stating that each must live in its own unique sensory world. And while the differences among humans may be more subtle than among species, the parallel seems clear that each human occupies a different perceptual and chemosensory world as well. Just as “color blind” people live in differently colored worlds than those who have full trichromatic color vision, so too do people live in different taste (and smell) worlds. But individual variations in taste and color perception differ in the numbers of people they impact. Color blindness affects a relatively small portion of the population, approximately 8% of men and 1% of women, whereas virtually all people live in their own taste and smell worlds. The determination of the degree to which these individuals' perceptual differences in taste can be attributed to differences in their genomes is the central focus of taste genetics.

There are many other factors that account for these individual differences in addition to genetics, including nutritional status, pre-and postnatal developmental history, hormonal status, time of day, as well as health, present drug treatment, and medical history. But one of the most common and potent determinants of individual taste differences are differences in people's genes. The protein receptors in our taste receptor cells respond to a wide variety of chemicals that are transduced into signals interpreted by our brains as sweet, salty, bitter, sour, and savory (umami) tastes. The genes that code for these taste receptors are highly variable and likely play a direct role in our individualized perceptions.

The study of taste genetics is important for several reasons. First, variations in our genes can determine how well we taste certain compounds. Second, how well we taste the chemicals that we perceive as sweet, sour, salty, bitter, and savory can impact whether we like the taste of a certain foods that contain these compounds. Third, whether we like the taste of a food can, in turn, affect whether we will eat it and, perhaps, how much of it; and this determines our nutritional status, which impacts our health, longevity, and quality of life. Importantly, the same sets of genes that are expressed in our mouths and affect our abilities to taste also code for proteins that are expressed throughout our gastrointestinal tract and can alter our “visceral taste.” We do not consciously perceive visceral taste inputs, but the stimulation of these taste receptors by ingested foods alters hormone secretions and our metabolism, and can also have a large impact on our nutritional status.

When examining the taste responses to a single compound, the distributions of taste sensitivities can be narrow for compounds, such as NaCl (salty) and sucrose (sweet), or quite broad for many compounds, such as some bitter compound for which sensitivities are spread over 1,000- or 10,000-fold differences in concentration. The most well known and studied of these bitter compounds is the antithyroid drug phenylthiocarbamide (PTC). This entry discusses the taste receptors of the five major taste sensations: bitter, sweet, savory, sour, and salty.

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