Inherited Taste Preferences

The term inherited implies that certain preferences for the basic tastes, sweet, salty, sour, bitter, and umami, have a component that is genetic or innate. While both the environment, and biology influence preferences for both foods, and the basic tastes, there are some preferences which are thought to be primarily innate. For example, all humans, and many mammals, exhibit an inherent liking of sweet taste from birth, and when presented with a sweet tasting solution, infants will increase their heart rate and show facial signs of pleasure. In contrast, humans tend to universally reject bitter and sour tastes at birth. This rejection of bitter and sour is thought to be a protective evolutionary advantage, since many poisonous substances have bitter and/or sour tastes.

One genetically influenced taste preference that has been well studied is the inherited ability to taste bitter thiourea compounds, such as 6-n-propylthiouracil (PROP), and phenylthiocarbamide (PTC). These compounds are both extremely bitter to 70 percent of U.S. adults and children (tasters), but are tasteless to the remainder [Page 405]of the population (non-tasters). This bimodal distribution of taste response is extremely rare, and therefore, has been of interest to scientists since it's discovery by a chemist name Arthur Fox in 1931. The distribution of tasters and non-taters varies widely around the world, such that some regions in Sub-saharan Africa have virtually no non-tasters, while India and the U.S. have some of the highest prevalences of non-tasters. The hypothesis that has been suggested, and supported by several studies, is that tasters and non-tasters have different food preferences. Tasters tend to dislike foods that are too bitter or hot (eg., black coffee, broccoli, hot peppers), while interestingly, non-tasters tend to have higher fat preferences and risks for obesity.

Several studies have been completed on the “heritability” of food preferences. Heritability is a term that means the amount of a particular trait or behavior that can be explained by genes. For example, heritability studies on obesity suggest that anywhere from 25-70 percent of obesity can be explained by heritable influences, or genes. Heritability studies are typically done using monozygotic (identical) and dizygotic (fraternal) twins, where one assumes that the monozygotic twins share 100 percent of their genetic material, while dizygotic twins share about 50 percent. Behaviors that are more similar in monozygotic twins would have a higher heritable component that behaviors that are more similar in dizygotic twins. Heritability studies on human food preferences suggest that for most specific food preferences, the contribution made by genes is low. However, some research has suggested that preferences for food groups, like high protein foods, fruits, and vegetables, may show higher heritability, at least in children.

Interestingly, a recent study (2007) in the American Journal of Clinical Nutrition found that liking for sweets and use of sweetened foods might have a significant heritable component. These studies are intriguing, as they suggest that some dietary inclinations might be genetically motivated.