edited by
GEORGE8.
KAUFFMAN
California State University. Fresna Fresna, CA 93740
The Development of Olestra, a for Dietary Fat R. J. Jandacek Procter and Gamble Miami Valley Laboratories, Cincinnati, OH 45239
Dietary Fat-Culture and Calorles Fat in the diet has made the hit lists of the National Cholesterol Education Program, the American Surgeon General, and the American Heart Association (1-3). Each of these groups has recommended that the American public eat less fat. The food industry is beginning t o respond to concerns about dietary fat with the development of reduced-fat foods and substitutes for dietary fat that maintain taste and eating qualities of the foods they replace. A recent approach is the use of engineered fats that offer the potential to provide all of the advantages of conventional fats in food preparation without contributing calories or saturated fat. This paper reviews the properties and development of olestra, an example of these engineered fats. What is this substance calledfat thatweare being asked to remove fromour diets? Why do we like it somuch? How does it differ from carbohydrates? Does i t have any benefits? How does the body use fat? Is it possible for chemistry to provide the joys of fat-the cream in ice cream, the smooth melting of chocolate in the mouth, the crispness of a potato chip-without the concerns raised by today's nutritional guidelines? In this article I will try to answer some of these questions. Nearly all of the fat that we eat is in the form of triglycerides (Fig. I), the common term for glycerol esterified with three fatty acids, or triacylglycerol compounds. Unsaturated fatty acids with cis double bonds, such as oleic and linoleic acids, do not easily align to pack in a crystalline array and therefore melt at low temperatures. The long-chain saturated fatty acids more readily pack together and form higher melting crystals. The properties of a fat molecule are dependent on its constituent fatty acids. For example, oleic acidbased olive oil is a liquid while stearic acid-based tallow is a solid a t room temperature. The desirability of fatty foods is not a recent dietary development. Fat once ranked with silk, gold, and perfume among one's wish list. The promise in the Bible, "And ye shall eat the fat of the l a n d (Genesis 45:18), underscores fat's desirability in previous millennia when the fatted calf was a banquet's piPce de resistance. A brief look a t the human form as depicted by Rubens three centuries ago is further evidence that the transfer of fat from food to body insulation was desirable and considered a mark of beauty. So today we find ourselves carrying centuries of fat-loving culture and recipes into our diets and are faced with ever476
Journal of Chemical Education
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increasing amounts of evidence that too much fat in the diet, especially saturated fat from animal sources, increases the risks of developing atherosclerosis, heart disease, and other health problems. Additionally, the rounded figures of Ruhens have now been replaced by the trim figures of athletes as the paragons of the body beautiful and presumably healthful. In the United States fat tvoicallv accounts for a o ~ r o x i mately 37q of the energy (csioiiesj in the diet ( 4 ) compared with less than 10%in societies where rice is a maior comDo. nent of the diet (5).Although some fat in the diet is necessary for healthand development as a source of essential fatty acids, we consume more fat than that required for optimum health. Dietary guidelines promulgated by public health organizations call for a reduction of total calories from dietary fat to 30% and areduction of calories from saturated fat to 710%of total dietary calories (1-3). The attainment of a high level of dietary fat by affluent societies reflects an enjoyment of foods with high levels of fat. The change in the economic status of Japan has been accom~aniedbv a doubling of oer caoita fat intake from 1960 to 1985 (6j. The reasons behind o& taste for chocolate andFrench fries DerhaDs originated inlean times when energy-dense foods were a benefit to health and survival. Triglycerides make up nearly all of the body's mass of fatty tissue and its stored energy. When the body is in need. of energy not provided by its small carbohydrate stores, triglycerides are hydrolytically broken down by lipase enzymes to produce fatty acids. These fatty acids are enzymatically oxidized to release usable energy, carbon dioxide, and water. Because of the large number of oxidizable carbon atoms, triglycerides are excellent sources of energy. By contrast, the oxygen-bonded carbon atoms of carbohydrate
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Olestra has been shown to fulfill all of the requirements for the ideal fat suhstitute described above. Animal and human studies with olestra have confirmed its nonabsorhability and the similarity of its properties to those of vegetable oils and fats. Results of numerous short- and long-term studies in rats, dogs, monkeys, hamsters, and humans have shown that it is safe for use in foods. Further studies have shown that i t does not interfere with the utilization of macronutrients. minerals. or water-soluble vitamins. Olestra is supplemented t o replace vitamin E, which would be removed from the diet by replacing some vegetable oils with olestra, and to compensate for the loss of any vitamin that remains solubilized in olestra and is not available for absorvtion. 20th-Century Changes In Fat Consumptlon Olestra can perhaps be viewed as the next step in the evolution of dietary fats and oils. The direction of this evolution has been influenced by the results of medical research and eoidemioloeic data that have increased our understanding or the re1a;ion of nutrition t o health. Recognition of problems associated with the high caloric density of fat and with high levels of saturated fatty acids in the diet has been a strong driving force toward the developments of foods with reduced total and saturated fat. In 1911 Crisco shortening was introduced with an allvegetable, cottonseed oil-based formulation as a replacement for lard. Early Crisco products were developed to provide performance and flavor that were superior to those of lard. As the understanding of the relationshiv of saturated fats to plasma cholesterolievels became apparent, shortening formulation emphasized decreasing saturated fatty acids and increasing unsaturated fatty acids. Today the saturated fatty acid content of shortenings ranges from 20 to 25% c o m ~ a r e dwith the 40 and 60% levels of lard and butter. respectively. A second steo was the wide marketing of veeetable oils with low levels of saturated fats and high l;?vels ofunsaturated fatty acids. Consistent with today's recommendation for reductions in saturated fat in the diet, today's canola oil contains only 6% saturated fatty acids. Following the same theme, margarines were developed that replaced butter. Margarines are required by federal standard of identity to contain no less than 80%fat tomatch the level found in hutter. The earls margarines used high levels of animal fats that were later displaced by coconut GI. By the 1940's, however, the principal margarine fat source was that of domestic vegetable oil. The margarines of today may contain less than 20% saturated fatty acids-far less than butter. More recently the emphasis on the reduction of fat of all sortsin thediet~hasled f~otherder~elopments in foods. Lowfat or "lite" foods are common in today's uupermarketu. The uje of emulsifiers and water in plare of fat in margarine has resulted in the appearance of numerous low-fat bread soreads that ran contain as little as 209 total fat. Frozen desserts with carbohydrate-based thickeners mimic ice cream but are fat-free. A recent development in the fat suhstitute area has been the vrocessine of ege white or milk orotein to form soherical p a r ~ i r l e s o f a ~ p r o x ' ~ ~ a1t um e l y indiameter. When &ended in water these microspheres give the mouth the feeling of
Figure 6.The structural formula o f olestra.
a creamv emulsion. Simnlesse (Tradename used hv the Nutrasweet Company, Deerfield, IL), a suspension of protein microsnheres. has recentlv been aooroved hv the Food and Drug Administration (FDA) lor u&as an ex;ender and tex. turizer in low-fat frozen desserts. Althoueh it is not stable to the heat of normal cooking conditions, S'implesse will presumablv be adavtable for use as a fat substitute in emulsionbased foods such as dairy products, spreads, and salad dressings. Because of its physical similarity to triglycerides, olestra can be used in cooking applications that are not possible with the currently available fat substitutes, and it can be blended with triglycerides. Theoretically, it can he used interchangeably with triglyceride fats and oils in virtually any food, including baking and frying applications. Olestra and other nonabsorbahle fat re~lacementsmav represent a partial solution to the dilemAa posed by thk ovoosine forces of nutritional recommendations that call for r i d ~ c e d ' h i e t a fat r ~ and the palatability of foods that provide the lubricitv and richness associated with hieh-la1 com~ositions. ~ n i m aand l human testing results and"manufact&ing specifications for olestraare currently being reviewed by the FDA as part of a Food Additive Petition that proposes use of olestra as a partial replacement of the fat in shortenine and oil used in hbme cookkg as well as use in commercial pieparation of fried snack foods like potato chips and corn chips. Llterature Clted 1. The Suzeon General's Report on Nutrition and Health, DHHS ( P H s ) Publicstion No. 88~~20211.1988 2. Dietary Cuideline~for Healthy A m d c o n Adults. A Stofamant /or Physicions and Haolrh Professionals by the Nutrition Committee, American Heon A88ociot~on: Circulation 1988,77,72IA-724A. 3. Netionsl lnrtitutesof Health. Arch.Intern. Med. 1986.148.36-69. 4. Netional Research Council. Dirt and Heolih ImpIicaLiona /or Reducing Chronic on met and ~ ~ s l t ~ha.t i o n d~ ~ s d e m washington, r ~ i s a a s ~e i s k : ~ committee he --, laxu 5. Keys,A.,at al. Am. J.Epidemio1. 1986,124, 903-915. 6. Lands, W. E. M.; Hamskezi, T.;Yamakari, K.; Okuyama, H.; Saksi. K.: Goto. Y.; Hubbard,V. S . Am. J. Clin.Nufr. 1990.51.991-993, 7. White, A,; Handler. P; Smith. E. L. Prinriple8ofBioeh~mistry, 3rd ed.; MeGraw-Hill: New York. 196(: p 282. 8. Abram8.C. K.; Hsmosh,M.; Hubbard, V. S.; Outta, S.K.:Hemosh, P, J. Clin. Invest. 1984.73.374-382. 9. Cardell. R. R.; Badenhsusen,S.:Porfer, K. R. J . CdlBiol. 1961.34.123-155. 10. Mattson. F. H.;Volpenhein,R.A. J.Bio1. Chem. 1964.9.2772-2777. 11. Mattion, F H.: Volpenheln, R. A. J LipidRes. 1972.13.325.328 12. Mattson, F.H.:Volpenhein,R.A. J.Nulr. 1972.102.1177-1180. 13. Jandscek,R. J.: Webb, M. R.Chem.Phys.Lipids 1978,22, 163.176. 14. Rinzi,G. P.;Taylor. H. M. J. Am. Oil. Chem. S o c 1976.I5.B9%40L.
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Volume 68
Number 6
June 1991
479