The Sixth Taste: Or, Why We Love Fat
Sweet, sour, salty, bitter, savory (or umami) and... fat?
Yogma/Flickr A Umami Burger
For better or worse, most of us have an affinity for fatty foods, and if scientists at Washington University School of Medicine in St. Louis are correct, that affinity may have less to do with the texture, smell, and overall greatness of a perfectly fried piece of chicken and more to do with our genetic makeup. According to their study, fat may be the sixth taste that the human tongue can detect, which in turn informs our perception of a food as a whole.
Prior studies have suggested that fat is indeed a basic taste that the human tongue can perceive; in one study, rats that did not have a functioning gene called CD36 had little or no preference for high-fat foods. The Washington University researchers' more recent study is the first to confirm that the tongue does perceive fat as a basic taste, and that the amount of protein produced by the CD36 gene affects a person's sensitivity to the presence of fat in foods. Or, in science-speak: "This is the first experimental evidence for a role of CD36 in fat gustatory perception in humans."
The researchers aimed to "understand how our perception of fat in food might influence what foods we eat and the quantities of fat that we consume." Accordingly, study participants were asked to drink solutions from three different cups, one of which contained a small amount of fatty oil while the other two were fat-free.
After tasting all the solutions, they were asked to identify which cup was not like the others. The results: some people really can taste the fat. And that sensitivity can be linked back to that CD36 gene, as participants whose bodies produced the most CD36 protein "were eight times more sensitive to the presence of fat than those who made about 50 percent less of the protein."
Significantly, the research suggests that there is something of a tolerance for fat. That is, the more fat you consume, the less sensitive you are to the taste of it. This in turn implies that the more fat you eat, the more fat you have to consume in order to satisfy a fatty craving. The next logical step in this fat research, then, is to determine "whether our ability to detect fat in foods influences our fat intake, which clearly would have an impact on obesity."
The results of the team's study was published in the February issue of Journal of Lipid Research.