Overweight and obesity are non-communicable diseases that have been reaching alarming levels worldwide. The nutrient unbalanced food and the sedentary lifestyles are contributing to health concerns in metabolic, immunological, and neurological deregulations. According to the World Health Organization, conditions such as diabetes mellitus and cardiovascular diseases are decreasing years of healthy and productive life across populations. Developing countries, such as Mexico has the highest prevalence for overweight and obesity in adulthood, with an incidence rate around 180 cases for every 100,000 inhabitants, which is around 60% of population, and doubles worldwide rates (Mexican Ministry of Health).1

Taste perception exerts heavy effect on eating behaviors; besides it is a modifiable ability that shows different levels of sensitivity across different stages of life, sex, circadian rhythm, and satiety hormones. The gustatory perception of sweet, sour, salty, bitter and umami taste is diminished as age increases. On the other hand, gustatory perception in women is higher than in men. The umami tasting is more pronounced in Chinese than American population, being the latest more sensitive to bitter and sour flavors than the former.2, 3, 4 Regarding the temporal effect of molecules for gustatory perception, the sweet and fat tastes have been related to circadian rhythms, as well as satiety signal communicated through leptin levels may decrease sweet perception in mouth. Nonetheless the natural variation of taste perception, the environment is a determinant for the food preferences, as is evident from the womb, where the amniotic fluid carrying tastant molecules for perception is a factor delineating early gustatory sensitivity in life, but from then on, the familiar, social and educational surroundings are relevant elements molding food preferences, over the taste perceptions.5

Bitterness perception is a unimodal sensation to multiple molecules with divergent structures, as different compounds are tasted in the same taste-receptors cells (TRCs) from the buds in the tongue. There is a multilevel signal according to the diversity and quantity of protein receptors expressed in the cell membranes of TRCs, but the restricted innervation makes the bitter signal convergent to one same sensation. A large family of approximately 25 protein receptors coupled to G proteins (GPCRs) coded by T2R genes, are responsible for the bitter sensation signal, which is transmitted through the TRCs. The TAS2R38 receptor is specifically activated by molecules with a very similar chemical structure, exemplified by compounds like phenylthiocarbamide (PTC). This chemical similarity extends to certain compounds found in green leafy vegetables, particularly those belonging to the Brassica family. Within these cruciferous vegetables, glucosinolates possess a thiourea chemical group that is directly linked to the bitter taste experienced upon their consumption.

The polymorphisms of the TAS2R38 receptor that configurate different haplotypes affect the consumption of food with a bitter taste, and presumably the consumption of food in general.6

There is a wide genetic variety in the sequence of the TAS2R38 gene that encodes the receptor amino acid sequences that impact the bitterness perception. There are nearly 21 diplotypes currently known for TAS2R38, of which the 3 PAV/AVI combinations are present in >85% of the population.7 Bitterness sensation derived from genetic conformation has been successfully searched since the mapping of the above-mentioned human gene (1999) in >100 reports, yet the reduction of the scope from the alleles, individual single nucleotide polymorphisms (SNPs) or haplotypes to 2 or 3 phenotype categories for tasting, not tasting or moderated tasting of PTC has shown consistent results.8 Since the 1990s, 3 distinct levels of bitterness perception have been identified: non-tasters, moderate tasters, and supertasters. Extreme levels, non-tasters and supertasters, each account for approximately 25% of the population, while moderate tasters constitute the remaining 50%. This trait is best explained by a hereditary pattern of incomplete dominance and allele multiplicity for the same gene. A specific dyplotype defines dimorphic characteristics for the receptor protein, as AVI/AVI (Alanine, Valine, Isoleucine) conformation determines a null sensitivity to the bitter taste of PTC-like molecules (non-tasters) and the PAV/PAV (Phenylalanine, Alanine, Valine) constitution is found in PTC super-taster individuals or tasters, while in the middle the heterozygous haplotype (PAV/AVI) partly explains the intermediate phenotypic diversity of moderated tasters. This quasi-monogenetic human characteristic shows a fair correlation between genetic and phenotype configurations with nearly 85% of certainty for non-tasters and super-taters individuals, although other receptors, such as the TAS2R4 may be involved too.6, 9

Although the direct association between the genotype for the TAS2R38 gene and the phenotypic perception of bitter has been proved, the relation among PTC perception, food preferences and body conformation is barely clear. Former studies found that tasters tend to have overweight, but controversy has been seeded, as some report that tasters may have normal weight.10 Additionally, AVI/AVI non-taster individuals have been related to obesity.11 In the case of food choices, the sweet and fat intake may be preferred for tasters, yet results are inconsistent, contrary to vegetables consumption, where data points to vegetables may be preferred by non-tasters. Therefore, this study investigated the association between PTC sensitivity and body composition in a young population, considering sex differences. In this study, we determined that PTC perception, without directly referring to genetic composition, aligned with the known distribution of PAV/AVI alleles. The expected proportions for homozygous genetic determinants of PTC tasters (PAV/PAV) and non-tasters (AVI/AVI) were found in 27% and 18% of the population, respectively. This also showed a harmony of over 85% between haplotypes and the sensory phenotype.6 We found that PTC perception is different across sex groups, men showing the most constant tendencies in the relationship between PTC phenotype and body composition parameters than women did. These results contribute to understand the complex matrix of variables configurating body composition and taste perception relationships, especially bitterness that may influence vegetables consumption in diet, alongside the sex differences which must be set in the context of these evaluations.