Friday, January 13, 2012

Tongue probably contains taste buds for fat

It is well known that humans have an affinity for fatty foods. Because of the wealthy abundance of food in the Western world, obesity is rapidly becoming one of the biggest (literally) problems. One explanation for our cravings of food containing high amounts of fat, is evolution favouring the intake of a lot of energy-dense food. After all, in the era of the cave man, you never knew when your next meal was going to be. Though thousands of years have gone by, we still possess those genes. Now, scientists from the University of Washington have discovered that a human tongue probably contains receptors that are able to make us taste fat.

In their study, the researchers made human participants taste three solutions, visibly indistinguishable from one another. One of the liquids contained a certain amount of oil, which is basically liquid fat. Participants were asked to identify the odd one out by taste, which would be the fatty solution, the other two being fat-free. Results showed that some people were much more sensitive to the presence of fat than others. It shows the human tongue is probably capable of detecting fat, but we are not all equally adept at it.
Differences in sensitivity to fat were attributed to a gene called CD36. People who possessed high levels of the protein that is made from the CD36 gene were found to be eight times more sensitive to fat. When studying the protein in obese people, they did not find a marked level increase or decrease, but rather a large variation. Because animal research showed that high fat diets result in decreased sensitivity towards fat, one would expect the levels of CD36 to drop in obese participants. Therefore, it cannot simply be the cause of all fat cravings, it is likely that other factors play a role as well. However, the protein was already identified in previous research as a mediator of fatty acid uptake, the basic components of fat.

Studying fat cravings is relevant to counter obesity, which is becoming an increasingly big problem in the Western world. Increasing CD36 levels may reduce our cravings, as low levels result in lower fat sensitivity. High levels of CD36 improve the uptake of fatty acids, and therefore satisfy our cravings faster. Any new discoveries we make in the fat detection pathway will also be relevant. Previous studies on obesity identified genetic modifications that can lead to obesity, as well as a gene that helps you maintain a balanced weight.

Not all CD36 genes are the same. The scientists found genetic variants that reduce the level of protein being made, which is believed to be present in 20 percent of the population. When possessing such a variant, it means more fatty foods are needed to satisfy the cravings. Equally, it probably means a rather large subset of the population has higher than normal cravings for fat.

For future research, the question will be whether we can actually locate the fat receptor on the human tongue. We may have a clear hint to its existence, as we are able to show differences in fat detecting capabilities in food consumption, but we do need to find the receptors on our tongues which identify fat. It is however clear that our body, in some sort of way, is capable of detecting fat, and may explain our cravings for it. That, in turn, is relevant to the treatment of obesity.

No comments:

Post a Comment