Do polymorphisms in chemosensory genes matter for human ingestive behavior?

Abstract

In the last decade, basic research in chemoreceptor genetics and neurobiology have revolutionized our understanding of individual differences in chemosensation. From an evolutionary perspective, chemosensory variations appear to have arisen in response to different living environments, generally in the avoidance of toxins and to better detect vital food sources. Today, it is often assumed that these differences may drive variable food preferences and choices, with downstream effects on health and wellness. A growing body of evidence indicates chemosensory variation is far more complex than previously believed. However, just because a genetic polymorphism results in altered receptor function in cultured cells or even behavioral phenotypes in the laboratory, this variation may not be sufficient to influence food choice in free living humans. Still, there is ample evidence to indicate allelic variation in TAS2R38 predicts variation in bitterness of synthetic pharmaceuticals (e.g., propylthiouracil) and natural plant compounds (e.g., goitrin), and this variation associates with differential intake of alcohol and vegetables. Further, this is only one of 25 unique bitter taste genes (TAS2Rs) in humans, and emerging evidence suggests other TAS2Rs may also contain polymorphisms that a functional with respect to ingestive behavior. For example, TAS2R16 polymorphisms are linked to the bitterness of naturally occurring plant compounds and alcoholic beverage intake, a TAS2R19 polymorphism predicts differences in quinine bitterness and grapefruit bitterness and liking, and TAS2R31 polymorphisms associate with differential bitterness of plant compounds like aristolochic acid and the sulfonyl amide sweeteners saccharin and acesulfame-K. More critically with respect to food choices, these polymorphisms may vary independently from each other within and across individuals, meaning a monolithic one-size-fits-all approach to bitterness needs to be abandoned. Nor are genetic differences restricted to bitterness. Perceptual variation has also been associated with polymorphisms in genes involved in odors associated with meat defects (boar taint), green/grassy notes, and cilantro, as well as umami and sweet tastes (TAS1R1/2/3). Here, a short primer on receptor genetics is provided, followed by a summary of current knowledge, and implications for human ingestive behavior are discussed.

Perceived 6-<i>n</i>-Propylthiouracil (PROP) Bitterness Is Associated with Dietary Sodium Intake in Female Japanese College Students

“…Previous reports have shown that the response to PROP was associated with increased bitterness and therefore reduced the liking for such vegetables as Brassicaceae (cruciferous) (27,32,47). The present participants, however, despite the apparent negative correlation for Brassicaceae vegetables, reported that the perceived PROP bitterness was not negatively correlated with the total vegetable intake (Tables 1 and 2).…”

“…Such individual difference in the PTC/PROP taste status or TAS2R38 variation has been demonstrated to result in differences in the liking for some vegetables, fatty foods, spicy foods and alcoholic beverages (27,31,32). Previous studies have reported that PTC/PROPtasters had a lower consumption of glucosinolate-containing vegetables than non-tasters (27).…”

Influences of weight, age, gender, genetics, diseases, and ethnicity on bitterness perception: a narrative review of current methodological aspects

“…Regarding gender, three articles reported that women are more sensitive to bitter taste also during pregnancy [22,23,43], and one did not find differences between genders regarding the number of gustatory papillae [50]. Different genetic expression, mainly of TAS2R38 and changes in the sensitivity to bitterness sensitivity, have been reported, influencing eating behavior and food preference, including alcohol ingestion [52,53,62]. Ethnic or cultural differences should always be considered because they appear to be crucial factors for food preference, justifying the discrepant results observed in the selected studies.…”

Variation in the Ability to Taste Bitter Thiourea Compounds: Implications for Food Acceptance, Dietary Intake, and Obesity Risk in Children

“…These early studies paved the way for nearly a century of research to understand the inheritance, molecular genetics, dietary implications, and evolutionary significance of this genetic variant. It is the most commonly researched genetic variation in chemosensation, but it is by far not the only example (67).…”

“…TAS2R38 and PROP status are well studied, but numerous other polymorphisms impact taste perception, with potential implications for dietary intake (67). Additional studies are needed to understand how these polymorphisms interact with TAS2R38 variation and the PROP phenotype to influence eating behaviors and chronic health.…”