Changes of Taste, Smell and Eating Behavior in Patients Undergoing Bariatric Surgery: Associations with PROP Phenotypes and Polymorphisms in the Odorant-Binding Protein OBPIIa and CD36 Receptor Genes.

Bariatric surgery is the most effective long-term treatment for severe obesity and related comorbidities. Although patients who underwent bariatric surgery report changes of taste and smell perception, results from sensory studies are discrepant and limited. Here, we assessed taste and smell functions in 51 patients before, one month, and six months after undergoing bariatric surgery. We used taste strip tests to assess gustatory function (including sweetness, saltiness, sourness, umaminess, bitterness and oleic acid, a fatty stimulus), the "Sniffin' Sticks" test to assess olfactory identification and the 3-Factor Eating Questionnaire to assess eating behavior. We also explored associations between these phenotypes and flavor-related genes. Results showed an overall improvement in taste function (including increased sensitivity to oleic acid and the bitterness of 6-n-propylthiouracil (PROP)) and in olfactory function (which could be related to the increase in PROP and oleic acid sensitivity), an increase in cognitive restraint, and a decrease in disinhibition and hunger after bariatric surgery. These findings indicate that bariatric surgery can have a positive impact on olfactory and gustatory functions and eating behavior (with an important role of genetic factors, such PROP tasting), which in turn might contribute to the success of the intervention.