propylthiouracil and Ageusia

The ability to taste 6-n-propylthiouracil (PROP) may be associated with body composition, but previous findings from observational studies are conflicting and cannot be interpreted causally. The aim of this study was to estimate the causal association between PROP taster status and body composition in a population-based cohort study.. The study was embedded in a population-based prospective birth cohort study. The TAS2R38 genotype (rs713598) was used as an instrumental variable (IV) to obtain unbiased effect estimates of the relation between PROP taster status and body weight (n=3778). Adiposity measures included body mass index (BMI) and fat mass measured by dual- energy X-ray absorptiometry scan at the child's age of 6 years. Associations were investigated using both ordinary linear regression (OLS) and two-stage least squares regression (2SLS).. Non-taster girls had higher BMI standard deviation scores (SDS) and higher body fat as compared with taster girls (results from linear regression BMI SDS: -0.09, P=0.023, body fat mass (%): -0.49, P=0.028). The TAS2R38 genotype predicted PROP phenotype (F=240), indicating a strong IV. The 2SLS effect estimates were imprecise but similar to the observational estimates (-0.08 for BMI SDS and -0.46 for body fat mass %) and were not significantly different from the OLS results (Hausman test: P>0.10). For boys there were no differences observed between tasters and non-tasters.. Our findings suggest a causal relation between PROP taster status and body weight among 6-year-old girls; Mendelian randomization was consistent with conventional estimates. In contrast, body weight among boys appeared to be independent of the PROP taster status. Further research should focus on possible underlying pathways, such as dietary behavior.

Topics: Absorptiometry, Photon; Ageusia; Body Composition; Child; Cohort Studies; Diet; Feeding Behavior; Female; Food Preferences; Genotype; Humans; Male; Mendelian Randomization Analysis; Propylthiouracil; Prospective Studies; Receptors, G-Protein-Coupled; Surveys and Questionnaires; Taste

Taste blindness to the bitterness of 6-n-propylthiouracil (PROP) may be a genetic marker for food preferences and dietary choices that ultimately influence body weight. A previous study in middle-aged women showed that those who were taste blind to PROP (i.e., nontasters) had higher BMIs than those with the greatest sensitivity to PROP (i.e., supertasters). This study tested the hypothesis that the nontaster phenotype was associated with greater adiposity in middle-aged women.. Forty women with a mean BMI of 26.6+/-1.3 kg/m2 and a mean age of 41.8+/-1.8 years were recruited from the local community. They were classified as nontasters (n=8), medium tasters (n=18), or supertasters (n=14) of PROP using a filter paper screening procedure. Anthropometric measures included height, weight, body fatness, triceps skinfold thickness, and waist circumference. Dietary restraint and disinhibition were also measured to assess cognitions associated with body weight.. BMI was 6.2 units higher in nontaster women compared with supertaster women (29.7+/-0.9 vs. 23.5+/-0.9, respectively; p<0.05). Body fatness (p<0.01) and triceps skinfold thickness (p<0.05) were also higher in these women. Waist circumference showed a trend in the appropriate direction. Although disinhibition was associated with greater adiposity, the relation between PROP status and adiposity was not altered after controlling for disinhibition.. The PROP nontaster phenotype was strongly associated with several measures of adiposity in middle-aged women. These data confirm our previous findings and suggest that the PROP polymorphism may be a reliable indicator of weight gain susceptibility.

Topics: Adipose Tissue; Adult; Ageusia; Body Composition; Body Mass Index; Body Weight; Female; Humans; Middle Aged; Propylthiouracil; Skinfold Thickness; Statistics, Nonparametric