The roles of carbonic anhydrase in gustation, olfaction and chemical irritation

Chemogenic Subqualities of Mouthfeel

Mouthfeel refers to the physical or textural sensations in the mouth caused by foods and beverages that are essential to the acceptability of many edible products. The sensory subqualities contributing to mouthfeel are often chemogenic in nature and include heat, burning, cooling, tingling, and numbing. These "chemesthetic" sensations are a result of the chemical activation of receptors that are associated with nerve fibers mediating pain and mechanotransduction. Each of these chemesthetic sensations in the oral cavity are transduced in the nervous system by a combination of different molecular channels/receptors expressed on trigeminal nerve fibers that innervate the mouth and tongue. The molecular profile of these channels and receptors involved in mouthfeel include many transient receptor potential channels, proton-sensitive ion channels, and potassium channels to name a few. During the last several years, studies using molecular and physiological approaches have significantly expanded and enhanced our understanding of the neurobiological basis for these chemesthetic sensations. The purpose of the current review is to integrate older and newer studies to present a comprehensive picture of the channels and receptors involved in mouthfeel. We highlight that there still continue to be important gaps in our overall knowledge on flavor integration and perception involving chemesthetic sensations, and these gaps will continue to drive future research direction and future investigation.

Factors affecting flavor perception in space: Does the spacecraft environment influence food intake by astronauts?

The intention to send a crewed mission to Mars involves a huge amount of planning to ensure a safe and successful mission. Providing adequate amounts of food for the crew is a major task, but 20 years of feeding astronauts on the International Space Station (ISS) have resulted in a good knowledge base. A crucial observation from the ISS is that astronauts typically consume only 80% of their daily calorie requirements when in space. This is despite daily exercise regimes that keep energy usage at very similar levels to those found on Earth. This calorie deficit seems to have little effect on astronauts who spend up to 12 months on the ISS, but given that a mission to Mars would take 30 to 36 months to complete, there is concern that a calorie deficit over this period may lead to adverse effects in crew members. The key question is why astronauts undereat when they have a supply of food designed to fully deliver their nutritional needs. This review focuses on evidence from astronauts that foods taste different in space, compared to on Earth. The underlying hypothesis is that conditions in space may change the perceived flavor of the food, and this flavor change may, in turn, lead to underconsumption by astronauts. The key areas investigated in this review for their potential impact on food intake are the effects of food shelf life, physiological changes, noise, air and water quality on the perception of food flavor, as well as the link between food flavor and food intake.

Carbonation dysgeusia associated with topiramate

PURPOSE

A case of carbonation dysgeusia associated with the use of topiramate is reported in order to bring awareness to a lesser-known adverse effect of the medication so that providers may be able to more effectively counsel patients and provide potential solutions.

SUMMARY

A 39-year-old Caucasian woman with longstanding epilepsy was initiated on topiramate therapy after experiencing a generalized seizure (she reported not taking any antiepileptic medication for years). Topiramate was started at a dosage of 25 mg by mouth twice daily and after 3 weeks titrated to a dosage of 100 mg by mouth twice daily for maintenance therapy. After initiation of topiramate therapy, the patient began to experience an immediate change in her carbonation perception when drinking carbonated beverages; all carbonated beverages, including seltzer and beer, tasted "flat." The patient remained on topiramate for the subsequent 12 months without her carbonation perception returning to normal but noted that drinking carbonated beverages through straws slightly mitigated the adverse effect. Case assessment using the adverse drug reaction probability scale of Naranjo et al indicated that topiramate was the probable cause of the patient's carbonation taste perversion.

CONCLUSION

A 39-year-old Caucasian woman developed chronic carbonation dysgeusia after initiation of topiramate following a generalized seizure.