Food Studies features the voices of volunteer student bloggers from a variety of different food- and agriculture-related programs at universities around the world. You can explore the full series here.

blue test

Imagine a taste test that is based on genetics — on a person’s genotype — and how the results of that test could confirm or explain one’s taste perception, food choices, dietary behavior, or body weight. Well, little circles of filter paper embedded with 6-n-propylthiouracil (PROP) can actually do just that. 

PROP is a compound that for people with the TAS2R38 genotype tastes extremely bitter whereas for people who have a differing genotype, the compound goes unnoticed. As shown on a recent episode of Anderson Cooper’s daytime talk show, you can tell immediately who is genetically programmed to taste it and who is not. Those who are sensitive to the compound, classified as super-tasters — a term initially coined by Dr. Linda Bartoshuk — are absolutely disgusted by the overwhelmingly bitter flavor while people who are not sensitive to it, non-tasters, just taste the filter paper. Statistically, about 25 percent of the population are super-tasters, twenty-five percent are non-tasters, and fifty percent are somewhere in the middle, classified as medium tasters.  However, PROP seems to reveal much more about a person than how well they can perceive and bear bitterness. 

One of the focuses of the Rutgers University Sensory Laboratory, as well as other sensory research facilities across the country, is to examine just that: To further explore the link between taster status and dietary behavior. By grouping subjects into taster groups and offering them varieties of food ranging in fat and caloric content, definite conclusions can be made. See, super-tasters do not just only perceive the bitterness of PROP and the bitterness of other compounds more, they actually generally perceive sweetness more, hotness (like from a chili pepper) more, textural aspects of dairy products (like creaminess and mouthfeel) more, and consume higher fat foods less frequently than non-tasters. Super tasters seem to be overall more sensitive to multiple sensory characteristics in general and are generally satisfied with smaller quantities of food because of their attuned sensory perception (like being satisfied with less salad dressing on a salad). 

For example, one study conducted in the sensory lab exposed subjects to a buffet-style eating atmosphere. By tracking how many calories, and specifically, how many calories of fat each subject consumed, researchers looked at whether non-tasters consumed more food and more foods with higher fat contents in comparison to super-tasters and medium tasters.  They did.

Naturally there are always exceptions, and taste genetics is just part of the story. There are so many other factors affecting a person’s food choices, yet considering taste is so subjective, PROP does at least give scientists clear and concise results. With the growing fight against obesity, many researchers believe that PROP will prove to be very useful. Hundreds of studies, in fact, have examined PROP status. One actually found that heavy smokers are significantly more likely to be non-tasters because super-tasters are far more sensitive to the bitterness of nicotine. Super-tasters too perceive the bitterness of alcohol more strongly than non-tasters and thus generally consume fewer alcoholic beverages per year. So it makes sense, that connections between taster status and body weight are being examined. Perhaps one day, PROP could be used as a screening tool to help doctors identify individuals who could potentially be at risk for excessive weight gain.

Anxious to know your taster status? Unfortunately PROP discs cannot be ordered online, but an easy at home test does exist. First, using a cotton swab, dab a small amount of blue food coloring on the front of your tongue. Then, using a mirror or with the help of a friend, compare your tongue to the two photos above. The lighter blue bumps on the tongue are fungiform papillae (structures that contain taste buds) and supertasters have a higher concentration of these structures (top section of photo) in comparison to non-tasters (bottom section of the photo). Thus, supertasters taste more perceptively because they actually have more taste buds.