Is that a PROP tab in your mouth, or are you just upset to see me?
That question could have been posed to a quarter of the audience during Linda M. Bartoshuk’s Bring the Family Address “Are You a Supertaster? How Can You Tell? What Does It Matter?” at the APS Annual Convention. During Bartoshuk’s unique address, the audience participated in scientific research on supertasters, a phenomenon of highly acute taste sensation gauged by how the participant reacts to a special tablet called PROP. Nontasters display a neutral reaction to the tab; a supertaster’s acrid response sweeps instantly across his or her face.
“Supertasters perceive everything as more intense,” said APS Fellow and Charter Member Bartoshuk, who studies genetic variations in the ability to taste as well as the pathologies and treatments that affect taste at Yale University . “Supertasters live in a neon taste world, and nontasters live in a pastel taste world.”
Audience members were given a survey, a strawberry Fruit by the Foot, a butterscotch dot, and a PROP tablet. By reading a slide that addressed possible health risks, attendees consented to the test. They then filled out the survey intended to gauge individual reactions to a wide variety of stimuli, along a scale ranging from no sensation to the strongest sensation imaginable.
When the time came to taste the PROP — a wafer-like paper impregnated with a chemical called 6M propothyiourea — a faint groan crescendoed through the crowd. To the befuddlement of supertasters, nontasters remained impossibly unaffected; vice versa, nontasters seemed convinced that their fellow participants were engaged in an Oscar-worthy display of histrionics. It is precisely this stark contrast that led Bartoshuk to study the anatomy and genealogy of supertasters — what she discovered along the way were potential health implications associated with the characteristic.
According to Bartoshuk, two unrelated elements create a supertaster — at least one dominant supertaster gene, and a high density of fungiform papilla, broad flat structures that house taste buds on the tongue.
“Supertasters have way more fungiform papilla on their tongues, and consequently way more taste buds,” Bartoshuk said. “Because taste buds are surrounded by pain fibers, the supertaster tongue feels much more pain.”
As a result, supertasters find many foods too intense. Vegetables are particularly unpalatable to supertasters, an aversion that carries serious health implications.
“Supertasters have an increase risk in colon cancer because they don’t take in as many vegetables as nontasters,” Bartoshuk said. “Men who tasted PROP had more colon polyps” than those who didn’t.”
But like the child forced to eat broccoli for its nutritional value, supertasters get the good with the bad. They find fats too intense; in turn, their weight is low and blood profile is healthier, and they have a lower risk of cardiovascular disease. They are also less likely to embrace alcohol, which produces an intense bitter and oral irritation, though a clear association has only been shown in social drinkers.
What made Bartoshuk’s address so unique was that in addition to presenting new research she actually collected new data on strawberry, a sensation she had not yet tested. Participants opened their strawberry Fruit by the Foot, sniffed, and rated the smell. Then they plugged their noses and ate a piece, rated the sweetness, unplugged their noses to get what Bartoshuk called a “retroactive experience,” and rated the smell and sweetness again.
Bartoshuk’s aim was to test how different types of olfaction affect taste. One type is called orthonasal olfaction, which is the sensation of sniffing through the nose. The other is retronasal olfaction, which occurs after swallowing a food, when an odor is pushed up through the nose from within the body.
“We believe that retronasal olfaction is attached to taste in an interesting way,” she said. “We now believe that orthonasal olfaction, sniffing, is not related to what goes on in the mouth at all, but retronasal olfaction is. The more intense sensation you have coming from the mouth, the more intense the retronasal olfaction is.”
She predicted that supertasters would perceive greater strawberry scent when it’s in their mouths, but that the strawberry odor sniffed from the package would not correlate to PROP-tasting ability.
Whether or not the results will confirm Bartoshuk’s hypothesis won’t be known for some time. What she does know is the importance using the correct scale plays in receiving accurate results.
“We live in our own sensory worlds, and if individuals in two groups have lived in different worlds with some given sensory experience, members of each group will stretch or compress the scale to fit their own particular world,” she said.
To test this, Bartoshuk played supertasters and nontasters the same noise and asked them to rate it. Supertasters rated it very loud, between a boombox and a baby crying, while nontasters matched it lower, between a shout and a boombox. A more relatable example is the collective agreement that women who have had children have a higher “worst imaginable pain” than men.
“Two groups of people you might have assumed were having the same experience clearly are not,” she said.
To combat these research perils, Bartoshuk created the General Labeled Magnitude Scale, which treats different intensities on their own scales to clarify potential misinterpretations.
“Think about a woman who’s just given birth, and she’s just come out of the delivery and says the pain was very strong,” said Bartoshuk. “You bring her a bouquet of roses, and she smells it and says the roses smell very strong. Do you really think she means the rose odor matches childbirth pain in intensity? No.”
The scale’s flexibility allows Bartoshuk to examine differences between races, ages, and sexes. She found that preference for sweetness goes down for females over time and stays the same for males, and that bitter tastes are universally muted with age. She found that Caucasian men are by far the least likely to be supertasters, while Asian women are the most likely. She even found discrepancies in preference for dark or milk chocolate over time.
Bartoshuk made it clear that any sensory scale is worth testing if it might uncover a medical significance, and that health implications exist beyond those already discovered.
“We need to measure everything we can, it’s the key to what we do,” she said. “And the better we measure sensory and hedonic experiences, the better we’re going to be able to see if those experiences map onto behavior.”