Surprise! Fat proves a taste sensation

For decades, scientists who study the gustatory senses have argued that fat has no taste. Sure, it has texture and contributes to a food’s perceived richness. However, conventional wisdom has held that our mouths lack taste buds or other sensors specifically tuned to fat.

That view may be slipping away.

By studying 19 adults, Richard D. Mattes of Purdue University in West Lafayette, Ind., has shown that the share of consumed fat that travels, as triglycerides, into a person’s bloodstream

depends on whether the person tasted fat to begin with. Some as-yet-unidentified, fat-triggered oral stimuli appear to “prime the body to more efficiently absorb fats,” he finds.

Mattes had volunteers come into his lab for testing after an overnight fast. On two test days, they ate a capsule of fat that they could neither smell nor taste. On another two occasions, they fasted for 8 more hours. For a couple hours on one of the fasting days and one of the capsule days, the volunteers sniffed whiffs of cream cheese. On the other days, they rolled cream cheese in their mouths for 10 seconds, then spit it out. For this test, volunteers wore nose clips.

Mattes periodically assayed triglyceride concentrations in the volunteers’ blood during each test. As expected, when the volunteers ate nothing, triglycerides fell throughout the test day, regardless of whether they had tasted or smelled a fatty food. On the days that participants downed a capsule of fat, triglycerides rose over a 4-hour period and then fell.

This is where the taste connection showed up. When a person downing the fat capsule later tasted cream cheese but didn’t smell it, his or her body converted three times as much of the oil in the capsule into triglycerides as when that volunteer only smelled the cheese. Mattes reports his findings in the current Physiology & Behavior (volume 74, number 3).

The new data add to “mounting evidence that there is a taste cue for fat,” says Timothy A. Gilbertson of Utah State University in Logan. He says that his own research suggests that fat also serves “as a taste modulator” by enhancing a food’s sweetness or saltiness. Indeed, he says, this may explain “why we like ice cream and potato chips so much–their high fat accentuates their other flavors.”

Edmund T. Rolls of the University of Oxford in England remains dubious of such claims. Although his own work shows that the mouth can sense fat, Rolls argues that this probably traces to texture sensors. Indeed, he found that paraffin oil–not a fat–in the mouth activates the same brain neurons that cream, which is a true fat, does.

Janet Raloff is the Editor, Digital of Science News Explores, a daily online magazine for middle school students. She started at Science News in 1977 as the environment and policy writer, specializing in toxicology. To her never-ending surprise, her daughter became a toxicologist.

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