Written by Henry P. Barham, MD, Mohamed A. Taha, MD, and Natan Rosenfeld

Ever wondered why some people prefer certain foods or drinks and cannot have enough of it while others (maybe even within the same household, like their spouses, or kids) cannot even stand the sight of it? Why can some people drink black coffee without adding any sugar or milk to it, while others cannot tolerate even its smell? Why can some people finish a big bowl of green vegetables like lettuce, broccoli, and brussels sprouts, and others can’t stand it? While dietary preferences are one thing, some people actually have a genetic hypersensitivity to certain flavors. These people are called supertasters.

The bitter taste receptor family

To answer these questions, let’s start with some basic facts about the sense of taste. There are five basic tastes that humans can detect; these are salty, sour, umami, sweet and bitter. The bitter taste can be perceived via the taste receptors (T2Rs) located in the taste buds on the surface of the tongue with 25 receptors (members) discovered. Some investigators hypothesized that the bitter taste has a protective role in that people do not ingest bitter-tasting toxic chemicals. However this poison detection system is not perfect because not everyone perceives the intensity of a fixed bitter stimulus in the same way. The classic example of individual differences in bitter taste sensitivity is for a substance commonly used by the researchers in their studies called phenylthiocarbamide (PTC) and the related chemical propylthiouracil (PROP). Some people can detect these compounds at low concentrations, whereas others need much higher concentrations or cannot detect them at all.

But what causes bitter taste variation between people? 

The average person has 10,000 taste buds, or fungiform papillae, on their tongue. Someone who would be considered a substance bitterer has significantly more buds. For instance, if you take a 6-millimeter round section from the average tongue, it would contain around 15 to 30 taste buds. But this same surface area on a supertaster’s tongue would contain 35 or more. It was thought that the variation in bitter taste perception between people was related to the number and density of the taste buds located on the tongue surface, but it was discovered that these variations were linked to our genes. For example, you could have genes that enable you to perceive certain foods as extremely bitter, while your friend next to you does not taste any bitterness at all. A.L. Fox was the first to shed light into this matter more than 70 years ago, when he reported that PTC tastes extremely bitter to some people but not bitter at all to others. Since then, numerous studies have shown that the inability to taste PTC is inherited in our genes. In 2003, a gene (TAS2R38) that explained approximately 75% of the variation in PTC sensitivity was identified on chromosome 7. So, if you have the functional form of this gene you can be classified as a supertaster, while if you carry the non-functional form, you will be classified as a non-taster. 

Intermittently, investigators have observed that younger generations are more sensitive than their older counterparts to perceive the bitterness of PROP or PTC, with other investigators suggesting that people who were less sensitive to bitter compounds seemed to lose their sensitivity faster as they got older. 

A simple taste test can detect this bitterness variation

This bitter tasting characteristic is actually more common than you might think: 25 percent of Americans are considered supertasters. So we can use a supertaster test based on these bitter tasting compounds (PTC, PROP) to determine these genetic variations. This at-home test involves you tasting various chemicals on small strips of paper. You then rate how intense the taste is to you by completing an online form. You’ll receive the results immediately. 

The health effects of being a supertaster 

Being a supertaster isn’t inherently harmful, but supertasters tend to avoid cruciferous vegetables (kale, broccoli, brussels sprouts) due to their bitter flavors, and as a result may have an increased risk for certain cancers. Furthermore, supertasters often add excessive salt to their meals to mask any perceived bitterness, which can raise risk for heart disease. But according to recent research, being a supertaster improves your defense response against various pathogens in your respiratory system, among many other protective roles that scientists are still evaluating. So if you fall into the supertaster category, make sure you’re getting enough greens in your diet, and don’t be tempted by the salt shaker.

In conclusion, we can deduce that being a supertaster doesn’t depend on the number of taste buds on your tongue but is related to your genes (TAS2R), and that, similar to other characteristics in our shape and body functions, the bitter taste receptor genes showed variation between people. Finally, these variations are being currently studied with many promising results impacting our health and our quality of life. 

References

• The role of bitter and sweet taste receptors in upper airway innate immunity: Recent advances and future directions
• Age modifies the genotype-phenotype relationship for the bitter receptor TAS2R38
• Introduction | Are You A Supertaster? | CE Course
• Global diversity in the TAS2R38 bitter taste receptor: revisiting a classic evolutionary PROPosal
• Statistics on Taste | NIDCD
• Super Taster vs. Non Taster: Does it Matter for Your Health?