Olestra is a dietary fat substitute made by esterifying sucrose with fatty acids from edible oil. It is not absorbed or metabolized. Click here to view the structure of olestra.
Concerns have been raised by consumer groups, the public, and some in the medical community about some negative side effects of olestra. These include intestinal cramping and diarrhea and other gastrointestinal effects, depletion of fat-soluble vitamins and other nutrients, and a lack of data to show that there are health benefits to olestra (1).
Olestra has been shown to have no effect on the absorption of macronutrients (protein, carbohydrate, and fat are all absorbed normally in the presence of olestra) (2). It has been shown to cause a decrease in vitamin E (3). The FDA requires that the fat-soluble vitamins A, D, E, and K be added to olestra-containing snacks.
But there are also concerns about the potential depletion of carotenoids, micronutrients that are supplied in the diet by fruits and vegetables. There is evidence that dietary carotenoids help prevent cancer and heart disease. Also, a diet deficient in carotenoids may over time cause an irreversible eye disease called macular degeneration (1,4). One clinical study showed a significant decrease in carotenoids among study subjects who consumed low and high doses of olestra for 4 weeks (5).
With regard to the gastrointestinal effects, there is a consensus that some individuals who consume olestra do experience mild diarrhea and cramping. One study of olestra among healthy (non-obese) men reported no intestinal effects (6). Another study reported an increase in gut rumbling, cramps, flatulence and diarrhea among the group consuming olestra, but the olestra group reported an equal "feeling of well being" (7). Two studies that measured the effect of olestra on gastrointestinal transit time reported conflicting results: one reported no effect on gastric emptying time, and a slight increase in speed of transit in the small and large bowels (8), and the other reported accelerated gastric emptying and slower small bowel transit time (9).
With regard to the potential benefits of olestra, most authors cite the strong evidence that high dietary fat and overweight/obesity are associated with chronic disease such as heart disease, diabetes, and certain types of cancer. Consumers find it difficult to comply with low-fat diets because fat adds significantly to the pleasure of eating for many people (10). Therefore, a non-caloric fat replacer like olestra has the potential to provide a great benefit to consumers who wish to limit their fat intake.
Several clinical studies have addressed the question of whether a person who consumed olestra instead of fat will eat more to compensate for lost energy intake (6,7,11,12). Although these studies had varying results, they found that the compensating increase in energy consumed tended to be in the form of carbohydrates rather than fat, so that olestra in the diet did result in a lowering of the percent of total calories from fat. In addition, olestra does have a small beneficial effect on blood cholesterol (3,13).
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Prepared Summer 1997 by Bernadene Magnuson, Ph.D.
University of Idaho, Dept. of Food Science and Toxicology - EXTOXNET FAQ Team.