Olestra and Other Fat Substitutes
The idea behind all fat substitutes is to reduce a food’s fat and calories while maintaining the texture provided by fat. They often fall short, however. While most contain fewer calories than fat, they don’t withstand the cooking temperatures that natural fats do.
Olestra appears to be an exception. Because olestra is formed by chemical combination of sucrose (sugar) with fatty acids, it has properties similar to those of a naturally occurring fat. But, unlike the natural products, this synthetic substitute provides no calories or saturated fat because it is undigestible: It passes through the digestive tract but is not absorbed into the body.
Fat Substitutes – Health Concerns
As promising as that sounds, olestra and similar fat substitutes that may come along in the future raise new concerns: What effect can they have on the gastrointestinal system if they are not absorbed? Can they affect absorption of fat-soluble vitamins? Can they interfere with absorption of other nutrients or with drugs? What particular effects might they have in people with conditions that affect nutrition, such as intestinal disease?
Fat Substitutes – Toxic Effects?
Unlike other food additives, which make up only a minute amount of the diet, fat substitutes, such as olestra, have the potential to make up a substantial portion of the diet because they replace fat, a major dietary component. This raises another concern: how best to determine if there are possible toxic effects from such fat substitutes. The usual method for studying toxicity of food additives – giving upwards of 100 times the likely human intake of the substance to laboratory animals – is impractical for fat substitutes like olestra. It is not possible to feed laboratory animals the large amount of fat substitutes that would be required to conduct a traditional toxicology test as is done with other food additives to determine safety.
Fat in the Diet – Weight & Health Problems
Replacing fat in the diet is not as easy as it may sound. Contrary to public perception, natural fats actually have many useful roles in the diet. They are one of the nutrient categories essential for proper growth and development and maintenance of good health. They carry the fat-soluble vitamins A, D, E, and K and aid in their absorption in the intestine. They are the only source of linoleic acid, an essential fatty acid. And they are an especially important source of calories for people who are underweight and for infants and toddlers, who have the highest energy needs per kilogram of body weight of any age group.
Fat also plays important roles in food preparation and consumption. It gives taste, consistency, stability, and palatability to foods.
On the other hand, too much fat in the diet can be harmful. Fat is calorie-dense: It contains 9 calories per gram, compared to 4 calories per gram for protein and carbohydrates. So eating a lot of fat can result in excess calorie intake, which in turn can perhaps lead to undesirable weight gain.
Dietary Fats & Disease
Fat intake also is linked to several chronic diseases. There is some evidence of a link between high intakes of fat and a possible increased risk of certain cancers, such as breast, colon and prostate cancers. There also is a link between high intakes of saturated fat and cholesterol and an increased risk of coronary heart disease.
The Dietary Guidelines for Americans recommend that fat intake be limited to 30 percent or less of calories and saturated fat to less than 10 percent.
Many Americans are trying to reduce their fat intake. According to a survey by the Calorie Control Counci – an association of low-calorie and diet food manufacturers – nearly two-thirds of the adult U.S. population consume low- or reduced-fat or reduced-calorie foods and beverages, and two-thirds also believe there is a need for food ingredients that replace fat.
Manufacturers are responding by adding more and more reduced-fat foods to their product lines. These products often contain fat substitutes already approved by FDA.
Fat Substitutes – Types
Fat substitutes can be carbohydrate-, protein- or fat-based. The first type to reach the market contained carbohydrate as the main ingredient. Avicel, for example, is a cellulose gel introduced in the mid-1960s by FMC Corp., and N-Oil is a tapioca dextrin introduced in the early 1980s by National Starch and Chemical Co. These types of fat substitutes are used in a variety of foods today, including lunch meats, salad dressings, frozen desserts, table spreads, dips, baked goods, and candy.
Protein-based fat substitutes entered the market in the early 1990s. There are two that have been affirmed as “generally recognized as safe” (GRAS): microparticulated proteins from egg white or dairy protein and whey protein concentrate. Microparticulation is a process in which the protein is shaped into microscopic round particles that roll easily over one another. These fat substitutes give a better sensation in the mouth–“mouth feel” in industry parlance–than the carbohydrate-based ones and can be used in some cooked foods. However, they’re not suitable for frying.
Olestra Fat Substitute
Olestra is a fat-based fat substitute. Unlike the other fat substitutes, it provides zero calories. This is due to its unique configuration. Most fat substitutes mimic the molecular shape of fat – one molecule of glycerol attached to three molecules of fatty acids. With olestra, the glycerol molecule is replaced with sucrose and has six, seven or eight fatty acids attached. The fatty acids can come from a variety of vegetable oils, such as soybean, corn, palm, coconut, and cottonseed oils. The idea is that with this many fatty acids, digestive enzymes can’t get to the sucrose center in the time it takes for the substance to move through the digestive tract. The sucrose center is where breakdown of the substance for absorption into the body would take place.
Fat Substitutes- Olestra Studies
Since 1987, P&G has submitted to FDA more than 150 studies on olestra’s safety. These include:
- Animal and human studies to see whether olestra breaks down in the digestive tract.
- Animal studies to see how much, if any, olestra is absorbed into the body.
- Animal studies to see whether olestra can cause birth defects .
- Animal studies to see whether a diet containing olestra is associated with a higher incidence of cancer.
- Animal and human studies to determine olestra’s effects on absorption of the fat-soluble vitamins and five key water-soluble nutrients that are hard to absorb or are limited in the U.S. diet–folate, vitamin B12, calcium, zinc, and iron.
- Animal and human studies to determine whether adding fat-soluble vitamins to diets containing olestra can offset the losses of those vitamins that may occur with olestra consumption.
- Human studies to determine olestra’s potential to cause cramping, bloating, loose stools, diarrhea, and other gastrointestinal symptoms in healthy adults, healthy children, and adults with inflammatory bowel disease.
- Human studies to determine olestra’s effects on normal intestinal microflora functions.
- Animal and human studies to determine olestra’s effect on the absorption of drugs, especially those that attach to fat in the body, such as oral contraceptives.
Concerns About Olestra-Type Fat Substitutes Remain
Despite ongoing research and testing, concerns about olestra and olestra-type fat substitutes remain.
Diet Program can help you reduce your fat intake and lose weight. It also shows you how to eat sensibly and control your weight for life.