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

Despite the negative health consequences of a high sodium consumption, humans consume well above the recommended levels. This study examines whether or not the dietary intake of sodium was affected by individual variation of the perceived bitterness of 6-n-propylthiouracil (PROP), and examines the relationship between the perceived bitterness of PROP and the preferred NaCl concentration of broth. Female students (20-22 y old) were recruited from the university community. Genotypes of A49P and I296V polymorphism of the TAS2R38 bitter taste receptor were determined for each subject. Samples containing NaCl, PROP or broth in 5-mL portions were evaluated by sensory testing. The participants completed a food record for each diet. Our results indicate that the individuals perceiving PROP to be more bitter had consumed a greater amount of dietary sodium. In contrast, there was no significant positive correlation between an individual's perceived saltiness and the dietary sodium intake. Those who perceived PROP to be more bitter preferred a broth containing a higher concentration of NaCl. All of these correlations were apparent even after those subjects with TAS2R38 AI/AI homozygotes (PROP non-taster) had been excluded. In conclusion, the results of this study suggest that a factor affecting the bitter rating of PROP other than the AI/AI homozygotes of TAS2R38 contributes to the variation in sodium intake and the preference for salty food.

A case study on the association of variation of bitter-taste receptor gene TAS2R38 with the height, weight and energy intake in Japanese female college students.

One of the critical factors that determines individual differences in dietary behavior and nutritional status is the sensory-affecting quality of food, in particular its taste. Variation of one bitter taste receptor gene, TAS2R38, which is associated with the differential sensitivity to phenylthiocarbamide (PTC) and 6-n-propylthiouracil (PROP), has been demonstrated to affect the dietary intake pattern. A case study was performed to examine the association of the TAS2R38 genotypes/haplotypes with the body size (height, weight and BMI) and with the food and nutrient intake. Eighty-four college students, all females, with an age range of 18-21 y were recruited from the University of Shizuoka. The genotypes of two common single nucleotide polymorphisms in TAS2R38 (A49P and I296V) were determined by PCR-restriction fragment length polymorphism (RFLP) method. The height, weight and body mass index (BMI), and (in a subgroup of 47 subjects) food and nutrition intake estimated from 3 d of food recording, were compared between homozygotes for the PTC/PROP-nontaster haplotype (AI haplotype) and carriers with the PTC/PROP-taster haplotype (PV haplotype). The results show that the homozygotes with AI haplotype were taller and heavier than the carriers of PV haplotype, while BMI values were similar between them. The former group also had higher energy and carbohydrate intakes than the latter group. Neither vegetable nor dairy product intake was different between the homozygotes with AI haplotype and the carriers of PV haplotype. In conclusion, the PTC/PROP-nontaster TAS2R38 genotype/haplotype was associated with height and weight but not with BMI, which may in turn have influenced the energy and carbohydrate intakes.