Taste perception is a complex sensory experience, shaped by biological and environmental factors. Our ability to distinguish between sweet, sour, salty, bitter, and umami flavors allows us to identify nutrients and detect potential toxins in food. However, not everyone perceives these tastes with the same intensity. Individual differences in taste sensitivity are common.
Understanding Nontasters and the Specific Substance
A “nontaster” refers to an individual who does not perceive a bitter taste from certain synthetic compounds. The primary substances nontasters are insensitive to are Phenylthiocarbamide (PTC) and Propylthiouracil (PROP), synthetic chemicals used in scientific studies to assess taste sensitivity. When tasters encounter PTC or PROP, they experience a strong bitter sensation.
In contrast, nontasters report little to no taste when these compounds are placed on their tongue. Some nontasters might describe a slight chemical taste, or no taste at all. The difference in perception is stark, making PTC and PROP useful tools for classifying individuals into different taste sensitivity groups. This insensitivity is a specific phenomenon, not a general inability to taste bitterness from all sources.
The Genetics Behind Taste Sensitivity
Taste sensitivity to PTC and PROP is determined by a specific gene known as TAS2R38. This gene provides instructions for making a taste receptor protein found on the surface of taste receptor cells. The TAS2R38 gene has different variations, or alleles, which influence how effectively the receptor protein can bind to bitter compounds like PTC and PROP.
The most common alleles are “taster” (PAV) and “nontaster” (AVI). Individuals inherit two copies of this gene, one from each parent. Those with two copies of the PAV allele (PAV/PAV) are “supertasters” with a strong bitter taste. “Medium tasters” (PAV/AVI) experience a moderate bitter taste, while “nontasters” (AVI/AVI) have taste receptors less effective at binding these compounds. This genetic basis explains why taste sensitivity runs in families.
How Taste Sensitivity Influences Food Choices
Differences in taste sensitivity, particularly to bitter compounds like PTC and PROP, influence an individual’s food preferences and dietary habits. While PTC and PROP are synthetic, sensitivity to them correlates with sensitivity to naturally occurring bitter compounds found in various foods. For example, nontasters may find certain vegetables, such as broccoli, Brussels sprouts, kale, or cabbage, less bitter or even enjoyable. These vegetables contain glucosinolates, compounds that can produce a bitter taste.
Conversely, tasters and supertasters might perceive these foods as bitter, leading them to consume fewer bitter vegetables. This difference in perception can extend to other bitter items like coffee, dark chocolate, or certain alcoholic beverages. Nontasters might prefer stronger, more bitter coffee or hoppy beers, while tasters may opt for milder varieties. These varied preferences can impact overall diet quality, as a reduced intake of bitter vegetables might mean missing out on certain beneficial nutrients and phytochemicals.