A new study from Monell Chemical Senses Center and the QIMR Berghofer Research Institute suggests that a single set of genes affects a person’s perception of sweet taste, regardless of whether the sweetener is a natural sugar or a noncaloric sugar substitute. In the study, published in Twin Research and Human Genetics, researchers tested 243 pairs of monozygotic (MZ, or identical) twins, 452 pairs of dizygotic (DZ, or fraternal) twins, and 511 unpaired individuals. Each person tasted and then rated the intensity of four sweet solutions: fructose, glucose, aspartame, and neohesperidine dihydrochalcone (NHDC). The first two are natural sugars, while the latter two are synthetic, noncaloric sweeteners.
MZ twins have nearly identical genes while DZ twins share only about half of their genes. Studying twin pairs allowed the researchers to determine how much influence the twins’ shared genetics contributed to their perception of sweet taste intensity. The resulting data indicate that genetic factors account for approximately 30% of person-to-person variance in sweet taste perception.
The study also revealed that those who perceived the natural sugars as weakly sweet experienced the sugar substitutes as similarly weak. This suggests that there may be a shared pathway in the perception of natural sugar and high-potency sweetener intensity.
Scientists are still working to unravel the molecular processes behind how we detect the many different types of sweet molecules. Earlier studies with mice showed that there is one main detection pathway for noncaloric sweeteners and natural sugars, but also a second pathway that responds only to sugars. The current findings suggest that these two pathways might converge into a single experience of sweetness intensity.
The current study also found little evidence for a shared environmental influence on sweet perception. Assuming twin pairs took part in communal meals during childhood, this result challenges the common belief that access to foods high in sugar may make children insensitive to sweetness.
“Even though almost everyone—consumers, physicians, and public health officials—wants to decrease the amount of sugar in our diets, right now we have no tool that has the sensory equivalence of sugar,” said study author Danielle Reed, a behavioral geneticist at Monell. “However, if we can understand why some people have weaker sweetness perception, we might be able to adjust this attribute so we could reduce the amount of sugar in foods.”
