In a study of Olestra, the fat substitute recently approved for human consumption by the FDA, researchers from Pennsylvania State University concluded that human taste buds apparently don't detect the difference between the low-calorie fat replacer and regular fat when used in potato chips.
"This is important because it suggests that if we can get the taste and texture of fat-free and reduced-calorie foods right, then they can be just as satisfying to our sense of taste and texture as the regular version of that food, despite being lower in fat and calories," said nutrition researcher Debra Miller of Penn State's University Park campus, who reported the findings at Experimental Biology '96, an annual meeting of biologic and biomedical researchers.
Miller and her colleagues also found no difference in how fast people's taste for the two types of chips diminished, suggesting that neither fat nor calories provide sensory signals to taste buds that cause people to grow tired of a specific food. "If fat and calorie content are important to achieving sensory-specific satiety, then we would have expected different results from the two types of chips," Ms. Miller said.
The study--involving what Penn State's Barbara J. Rolls, phd, labeled the fat substitute most systematically investigated--provides additional evidence that humans find olestra agreeable to their palates and their stomachs.
Need for Real-Life Evidence
But as Dr. Rolls, Ms. Miller's coauthor, noted separately in a press conference, a great gulf separates the impressive support built up for Olestra and other fat substitutes in the laboratory and what might happen in the real world.
"There is really no evidence at all on how these products affect people in real life situations," Dr. Rolls said. "Ultimately, we need to know how the whole array of fat-substituted foods impact people's diets, both in terms of energy intake and the macronutrient composition, and if they're having an impact on body weight. It isn't an easy study. The kinds of ways people incorporate these foods into their diet isn't known at all."
Effects on Children Still Sketchy
Questions remain, as well, about the effects of fat substitutes on children, particularly young ones. A short-term study reported 3 years ago by Leann L. Birch, phd, head of Penn State's College of Health and Human Development, used Olestra in addressing the issue of whether children compensate for the calories eliminated from their diet with the use of fat replacers by eating more food, or if they actually have a reduction in total energy intake, which could cause developmental problems.
"Calories were essentially the same," Dr. Birch said, adding that the work she and her colleagues did was the only attempt she knew of to resolve the question.
A variety of fat replacements exist, including carbohydrate-based dextrins, modified food starches, polydextrose, and gums. Others include in their formulation monoglycerides or triglycerides. Olestra, formed by the esterification of sucrose with fatty acids from edible oils, can be used in cooking, baking, and, unlike other fat replacements, frying. Despite its sucrose lineage, the product lacks sweetness and looks, tastes, and feels like fat.
The FDA granted Procter & Gamble approval in January to market olestra for use in savory snack foods, such as cheese curls and potato and corn chips. Products fried in olestra, which P & G is selling under the brand name Olean, have recently entered three small test markets.
No Miracles Expected
No one should expect weight-wasting miracles from olestra or other fat replacers, advised John C. Peters, phd, Procter & Gamble's associate director for regulatory and clinical development, food and beverage products. "People expect these things to make people who are obese melt away and turn into nice, skinny people. That's generally not going to happen."
Fat replacers can only help people control or lose weight if they are part of a sensible diet, he stressed. "As someone said, this is a replacement for fat, not for common sense."
More than a dozen studies have addressed whether when fat is replaced with olestra people "make up that fat by eating other fatty food, so that they get the same amount of fat at the end of the day," Dr. Peters said. "The answer across the board is that there is no fat-specific appetite. So if you take the energy out by taking the fat out, people might make up some of the energy, they might even make up all of the energy, but they don't make up the fat. So you get the fat-reduction benefit."
Thin people who didn't need to cut calories maintained their same level of calories in some studies with olestra, but all still cut their fat intake.
However, the laboratory is not the lunch room. People can override the weight-control and/or reduced fat benefits of fat reducers by eating more of low-fat foods or by eating other fatty foods.
"Clearly, if people take things into their own hands, what I call cognitive override, they can do anything they want," Dr. Peters said. "What they do in their head, we will have to see."