The Science of Taste
“Children are born true scientists. They spontaneously experiment and experience and re-experience again. They select, combine, and test, seeking to find order in their experiences – “Which is the best? Which is the mostest? Which is the leastest?” They smell, taste, bite, and touch-test for hardness, softness, springiness, roughness, smoothness, coldness, warmness: they heft, shake, punch, squeeze, push, crush, rub, and try to pull things apart.”
-R. Buckminster Fuller
Taste is a composite sense that’s partly determined by the taste buds, but also affected by aroma, visual presentation, and even previous experiences. Because smell, appearance and our expectations have a lot to do with the way we perceive taste, our children (“little scientists”) who are tasting things for the first time, rely on their taste buds, their sense of smell, and other visual cues to decide if something tastes good or not. Typically, if a child thinks they’ll like a food, there’s a much better chance that they actually will. Similarly, if a child thinks they will not like a food, there’s a much better chance that they actually won’t. Obviously preconceived notions about the way a medication will taste often fall into the latter category. Children generally think they won’t like the taste of a medication simply because- its medicine!
So preventing taste and/or psychological aversions by modifying medication taste is beneficial not only for the experience at hand but for all future experiences. Allowing kids to choose the flavor of their medicine to a flavor that they prefer and like, not only improves the actual taste of the medication, but also helps to change their perceptions, thereby increasing the likelihood of a positive taste experience. Positive taste experiences lead to less medication struggle, improved medication adherence, and better health outcomes.
Now that we have addressed the “psychology of taste” we need to address the “physiology of taste” as well. Taste is a chemical sense which provides important information on the chemical composition of food. It is one of the body’s mechanisms developed to recognize foods needed for nutritional value, as well as a natural defense mechanism helping to identify harmful substances. For example, sweet tastes are associated with energy rich foods needed for survival whereas bitter flavors are more commonly associated with natural toxins to be avoided. Flavor, is created when additional senses such as sight and smell are included into the experience.
Taste buds are located on the papillae on the tongue. The average adult has approximately 10,000 taste buds, but children have more, including some dotted along the inside of their cheeks. Many taste buds lie along the walls of the papillae. Isolated ones also are present on the palate, the pharynx, and the epiglottis. Taste buds are comprised of taste cells with taste nerves interwoven between. When taste cells are stimulated, the taste nerves depolarize and send taste signals to the brain, including the hypothalamus, the thalamus, and the gustatory part of the sensory cortex – the “taste center”, where the signals are interpreted. The thalamus acts like a relay station, shunting the data onto appropriate cortical areas for processing. When combined with the sense of smell, flavor is perceived by the brain.
Five distinct tastes can be detected; Sweet- provides a recognition of energy rich nutrients; Salty – allows modulating the diet for electrolyte balance; Sour- typically indicates the presence of acids and allows for the detection of when foods may be spoiled; Bitter- allows sensing of diverse natural toxins; and more recently a fifth taste has been recognized known as Umami or savory- it is the taste of amino acids (e.g. meat broth or aged cheese). Many diagrams present “taste-zones” however it is now believed that while there are differences to taste sensitivity around the tongue, the different tastes are perceived in any area taste buds exist. Presence and density of taste buds may vary by individual. Therefore, taste is individual and subjective.
Thanks to extensive research on the sensory capabilities and preferences of children as it relates to flavor, we do know some objective facts. It is important to recognize that children by nature demonstrate a significant preference for sweet tastes and a greater aversion to bitter tastes. This helps explain why so many children struggle taking medication or eating certain vegetables, but have no problem eating candy and sugar coated cereal! As mentioned before, the rejection of bitter flavors is part of basic biology. Bitter flavors are most commonly associated with natural toxins and poisons; therefore rejection of such tastes is thought to have evolved to protect the consumer from harm. The problem is that the chemical structure of a many medications determines not only the pharmacological efficacy of a drug, but the bitter taste as well. Many medications are bitter by design. It is no wonder that children often resist medication administration-essentially it’s their self-defense mechanism. This issue further highlights the critical role taste plays in medication adherence among children. Parent reports reiterate that medication with poor taste is a viable barrier to administering medications.
Approximately 350 million liquid medications are dispensed in the U.S. each year, many of which are associated with poor palatability. While companies recognize palatability issues with medication administration, often only one flavor per formulation is manufactured. This is primarily due to Research and Development costs as well as production costs. Having the ability to customize the flavor of medications after-market, to mask unpleasant taste and/or meet patient preferences, can improve adherence. The literature supports taste as being a significant factor in adherence and recognizes that this issue should be considered when selecting medications, especially among pediatric patients. You should do the same. Now that you have a better understanding of the underlying psychology and physiology of taste, utilize your knowledge to be the best neighborhood “scientist-psychologist-pharmacist” in town!
By Ursula Chizihik, PharmD