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FATS, SUGARS MAY AFFECT BRAIN CHEMISTRY
Date: 9/3/02; Publication: United Press International; Author: Not specified



Fats, sugars may affect brain chemistry
Sep 03, 2002 (United Press International via COMTEX) -- Cheeseburgers, sodas and other fatty and sugary foods long have been known to contribute to obesity but science is beginning to discover how these tasty treats can disturb the action of key hormones in the body and consequentially alter brain chemistry.

Growing evidence suggests consumption of fats and fructose -- a type of sugar found in fruits and in processed beverages such as sodas and juice drinks -- affect the natural action of three important hormones: ghrelin, which is produced by the stomach to stimulate food intake but also recedes when appetite is sated; insulin, produced by the pancreas to regulate the fat cells; and leptin, produced by the fat cells to signal the brain the body is full.

Several studies have suggested that too much fat results in insulin resistance, creating a situation where hormone signaling becomes so gummed up the brain cannot tell the body when to put down the fork. The same appears to hold true for fructose.

"The more fat and fructose you have on your diet, the less effect you have on these hormones that keep your body stable," Peter Havel, an endocrinologist at the University of California at Davis, told United Press International.

"These hormones help keep your body weight stable," he said.

Sugar, like glucose, ignites insulin production, which then helps set off a biochemical chain reaction throughout the body that indicates fullness. Fructose, however, does not stimulate insulin production and this, researchers said, is a crucial link to understanding why some people develop obesity.

"When you drink beverages with lots of fructose ... you're not triggering insulin secretion or leptin" because leptin is dependent on insulin production, Havel explained. Ghrelin levels are not dropping in the stomach, therefore the body is confused. By consuming fructose-heavy products, the body continues to take in calories, but the hormones are not able to tell the body it is full and to stop eating.

"Many fast food meals are washed down with a large beverage," Havel said. "When you eat such a meal, you're not going to produce as much insulin and leptin and you're not going to lower your ghrelin as well."

If the brain and body do not receive signals that appetite needs have been met, then eating will continue and, in turn, the chances of obesity increase. This cycle raises one's risk for a slew of dangerous ailments such as heart disease, hypertension and diabetes.

Havel's research, conducted with the University of Pennsylvania in Philadelphia, looked at 12 women of normal weight, ages 20 to 40 and compared their blood samples on days they consumed fructose to days they consumed glucose. Although Havel would not go into to many details because the research has yet to be published, he did say the days of fructose consumption showed higher triglyercide levels, a risk for potential heart disease.

Havel said a 12-ounce soda contains about 25 grams of fructose. A 64-ounce soda -- the kind of "super-size" serving widely available at convenience stores, contains 130 grams. In contrast, an apple contains 13 grams of fructose, a banana has 7 and a peach contains 4. Plus, fruit provides several other needed nutrients such as fiber and vitamins that are not provided by fructose-heavy drinks.

"What is it about composition of diet that allows you consume more than you otherwise would?" asked endocrinologist Michael Schwarz of the University of Washington in Seattle, who also is investigating this issue. "If the phenomenon exists that you become (hormone) resistant under these conditions of obesity, then there must be reason for that, " Schwarz told UPI.

Stephen Woods, a psychiatry professor and director of the obesity research center at the University of Cincinnati, said the natural processes of our bodies and brains might have become too overwhelmed by the hyper-stimulating environment of ubiquitous high-caloric fast food.

"The food industry, particularly the fast food industry, is very good at making foods so appealing that people are willing to consume (them) and that will in turn override other types of (biological) controls, " Woods told UPI.

One of these controls is called cholecystokinin, or CCK, a signal that comes from the lower stomach to indicate fullness.

"There's lot evidence when you eat these calorically-dense, high-sugar, high-fat foods, that your body and your brain is less sensitive to CCK," Woods explained. "What that means is that you have to eat bigger meals in order to secrete enough CCK to turn off your appetite."

According to the U.S. Surgeon General's Office and the Centers for Disease Control and Prevention, the nation's girth continues to bulge. At present, 61 percent of the American population is either overweight or obese. As a result, health experts have been warning the public to minimize its intake of fatty and sweet foods.

One mystery scientists are pursuing is the link between genes and how fats and sugars affect the body and brain. Some people might be more genetically susceptible to developing hormone insensitivities as a result of their fat and sugar intake, while in others, environment might be the source of over-eating.

"When we live in a world with these stimuli that look good and smell good and taste good and are calorically dense," Woods said, "then we're going be heavier."

By KATRINA WOZNICKI, UPI Science News