Pam Dalton, research scientist at the Monell Chemical Senses Center in Philadelphia, PA, replies:
Historically, most people were of the opinion that our food preferences were determined by our experiencefrom the culture that we lived in and the type of food experiences we had; that you would come to prefer the things you were regularly exposed to, and you would be less likely to prefer things that were novel or unusual.
And in fact, theres a substantial line of research which suggests that experience does play a very important role in determining our preferences, and that those preferences may even be shaped prior to birth. Here at the Monell Center, theres a researcher whos looking at the diets of mothers and how that influences their childrens taste preferences pre-natally. It doesnt just have to be what you feed the babies in the first months or weeks or years of their lives, but it seems that because flavors of foodthe volatiles that are essentially giving you the flavorscan be transmitted through amniotic fluid, and of course the fetus is swallowing amniotic fluid while its in the womb. Their sense of taste and/or the olfactory organs and the taste organs are developed very early in pregnancy, so theyre actually getting pre-natal experiences with the flavors of their mothers diets. So theres a strong role for experience in terms of actually shaping what children will accept, and the evidence is that children who have had mothers that have ingested certain foods are more likely to come to prefer them in their early life than children who havent had those experiences.
So we cant rule out that experience plays an extremely important role in determining our flavor and food preferences. However, thats not the whole story.
Our sense of taste is determined by five different types of qualities: sour, salty, sweet, bitter and savory (the taste that the Japanese call "umami"). We believeand its being supported by physiological and molecular biology studiesthat there are different receptors for each of these distinct tastes. While it isnt true that you can only taste sweet on the tip of the tongue and bitter on the back of the tongue, it is the case that there may be a different distribution of these sensitive receptors across the tongue surface. So, while you can taste sweet everywhere and you can also taste bitter everywhere, there are different areas where you can taste bitter best or sweet the best.
Now it seems that some people tend to have a much higher density of papilla, where the taste buds, the receptors for taste, lie. Putting together studies that have asked people to taste bitter compounds or things that are sweet, while looking at the distribution of these taste buds on their tongue, has allowed some researchers to say that people who seem to have many more taste buds are experiencing certain tastes more intensely. Theres a compound called PROP, or 6-n-propylthiouracil, and whether or not you can taste it is genetically determined. For people who can taste it, its extremely bitter. And this is one of the tools of the taste researchersto be able to go out and look at the distribution of people who can taste this or not. It turns out that there are some people who cannot taste it at all, some people who can taste it and find it bitter, and some people who can taste it and find it so bitter that theyre ready to vomit on the spotits really horrible. Looking at these people who experience the PROP taste as very bitter, their tongues have many more of these densely packed taste buds. And it looks like they also find other taste qualities equally intense.
Obviously if things taste very bitter to you, like vegetables, youre probably less likely to prefer them than someone for whom the other flavors sort of blend. Things like beer, for example. One of the things that many people prefer in beer is a slightly bitter taste, or even a moderate bitter taste. Someone, however, who is a bitter "super taster" is probably going to find those kinds of beers completely unpalatable. So we dont really know exactly why some people may have more closely packed taste buds or receptors that make them super tasters, but there is evidence that there is a role for physiology as well experience in determining our preferences.
Actually there is a program going on in the Center right now thats trying to identify the genes. Well, the genes and receptors for bitter taste have been localized, but to understand the variation and how does this run in familiesthere are research programs looking at that right now, trying to map it out. There also is some evidence that bitterness can be influenced by hormonal status, particularly for women, although theres not as much evidence in support of that. But there clearly may be some physiological influences on taste that would then determine, or at least partially determine, preference, that have not been completely established.