Tastes Good? Fat Chance

Our taste buds go beyond sweet, salty, sour and bitter -- all the way to fat, new research contends

THURSDAY, Dec. 13, 2001 (HealthDayNews) -- For centuries, scientists figured that our taste buds were designed to detect only four flavors: salty, sour, bitter and sweet. Everything else that goes into the taste of, say, a chocolate bar was thought to be related to things like smell and texture.

But with the help of advanced technology, some researchers are beginning to think that people's mouths are full of sensors for other substances -- like fat.

If there is a taste bud for fat, food makers could use the new knowledge to create fake fats that would taste more like the real thing.

"We have not fully appreciated how we perceive fat, and that may contribute to why fat replacements are not as good as the real thing," said Richard D. Mattes, a professor of nutrition at Purdue University and co-author of a new study on the taste of fat.

The taste buds that line our tongues and the few others scattered around our mouths do more than distinguish lemon meringue from raw fish. They help us detect foods that are potentially good or bad for us, Mattes said.

"The fundamental challenge to omnivores is to determine what's food and what's not," he said. "Taste is the final gatekeeper, the last information you get before you make that ultimate decision of swallowing or not."

Evolution may have given us the ability to taste sweetness and salt to encourage the consumption of carbohydrates and electrolytes, respectively, he said. On the other side, sensors for sourness and bitterness may keep us from eating poisonous foods.

In recent years, a growing number of experts have contended that taste buds can sense something called umami, which is triggered by monosodium glutamate (MSG), an Asian seasoning that some scientists consider to be a health risk.

The debate over fat is not so clear-cut. Anyone who has compared non-fat ice cream to the premium stuff from Ben & Jerry's or Häagen Dazs knows that true fat is very different from fake fat. But researchers long thought that people simply sense the texture or smell of fat, not its taste, Mattes said.

To test that assumption, a Purdue research team gave crackers topped with cream cheese to four groups of students. One group was allowed to smell and taste the food, then spit it out; another could only smell it; and a third group could only taste it (their noses were plugged), then spit it out. The fourth group did not taste or smell the food.

The levels of fat in the blood of the 19 students were tested before and after the experiment. The blood fat levels rose three times as high in two groups -- those who both tasted and smelled the food and those who merely tasted it -- than in the group that did not taste or smell the food. Nothing happened in the group that only smelled the food.

The levels are significant because the body appears to prepare for the ingestion of fat by increasing the levels of it in the blood, Mattes said. It's not clear why the body does that, but there's no question that "there's something about the sensory exposure that is altering blood fat levels," he said.

The higher levels of fat in the blood, even if only present because fat has just been tasted, could raise a person's risk of heart disease, Mattes said. Further research will need to examine that possible risk and how it could be reduced.

The findings, which appear in the recent Physiology & Behavior journal, support the theories of food experts like Susan Schiffman, a psychology professor at Duke University.

Schiffman thinks we can clearly taste fat.

"When you put fats in your mouth and don't move your tongue or push things around, you can tell it's fat," she said. "It's definitely a fatty taste."

What To Do

Did you know we have taste buds all over our mouths, not just on our tongues? Learn more by visiting this taste bud fact sheet from the University of Michigan. It's designed for kids, but adults may find it worth a look.

Other facts about taste buds appear in this primer from an online biology textbook.

SOURCES: Interviews with Richard D. Mattes, MPH, Ph.D., R.D., professor of foods and nutrition, Purdue University, West Lafeyette, Ind.; Susan Schiffman, Ph.D., professor of medical psychology, Duke University, Durham, N.C.; November 2001 Physiology & Behavior
Consumer News