Dietary fat substitutes

Nutrition Research, Vol. 14, No. 10, pp. 1605--1619, 1994 Copyright 9 1994 Elsevier Science Ltd Printed in the USA. All rights reserved 0271-5317/94 $6.00 + .00

Pergamon

0271-5317(94)E00081-6

DIETARY FAT SUBSTITUTES Charles J. Glueck, M.D. I, Patricia A. Streicher, R.D., Ellen K. Illig, M.Ed., R.D., and Karen D. Weber, R.D. Cholesterol Center The Jewish Hospital of Cincinnati,

Inc.

ABSTRACT This paper discusses the role fat plays in the diet. It focuses on the types of fat substitutes, the appropriate foods for their use and the fat-like qualities they possess. Safety issues and the long term impact of fat replacers are also reviewed. KEY WORDS: Substitutes, Carbohydrate, Lipid

Guidelines,

Safety, Protein,

INTRODUCTION Historically, dietary fats and oils have been considered a primary source of energy without regard to the health effects of their specific complement of fatty acids and sterols. The term "fat substitute" implies that a substance has certain desirable physical or organic attributes of the fat that it replaces without any of the undesirable properties. Usually, a fat substitute is not a fat; however, the term has been used to describe fats that are not digestible or only partially digestible when consumed by humans (i). The impetus to research and develop fat substitutes has come from several different directions. In 1987, the National Center for Health Statistics listed ten leading causes of death in the United States. Of the ten, diet plays a part in five: heart disease, cancer, stroke, diabetes and atherosclerosis. In 1988, the Surgeon General's Report on Nutrition and Health suggested that most people reduce their consumption of fat and cholesterol (2). Also in 1988, the Nutrition Committee of the American Heart Association recommended that all healthy American adults should reduce their total fat intake from 37 percent to less than 30 percent of total calories in an effort to prevent heart and vascular diseases (3). HEALTH ISSUES The relationship of dietary fat and cholesterol to coronary heart disease is supported by extensive and consistent clinical, epidemiologic, metabolic and animal evidence. Studies strongly indicate that the formation of atherosclerotic lesions in coronary arteries is increased in proportion to the levels of total and low density lipoprotein (LDL) cholesterol in blood, which, in turn, are increased by diets high in total fat. Dietary intervention is now considered appropriate for persons with total serum cholesterol levels higher than 200 milligrams per deciliter (mg/dl). It is recommended that these individuals lower not only their intake of total and saturated fat, and cholesterol, but reduce their caloric iCorresponding author: Charles J. Glueck, Cholesterol Center, The Jewish Hospital, 3200 Burnet Ave., cincinnati, OH 45229, U.S.A. 1605

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intake as well. The National Cholesterol Education Program (NCEP), recognizing that obesity is associated with elevated levels of low density lipoprotein and is an independent factor for cardiovascular disease, suggests that caloric intake be adjusted to achieve and maintain a desirable weight (4). The Second R e p o r t o f the National Cholesterol Education Program Expert Panel on Detection, Evaluation and Treatment of High Cholesterol in Adults, as reported in the Journal of the American Medical Association (JAMA) in 1993, emphasizes the clinical approach in primary prevention of coronary heart disease. Dietary therapy remains their recommended first line of treatment of high blood cholesterol (5). Growing evidence also suggests that total fat and caloric intake may increase the risk of certain types of cancers and other diseases. High fat diets have been associated with breast, colorectal, endometrial and prostate cancers, as well as with the development of obesity. One-fourth of American adults are overweight and nearly one-tenth are severely overweight. It has also been reported that 22 percent of children in the United States between the ages of 12 and 17 are obese (6). since obesity is a risk factor for coronary artery disease and some types of cancers, as well as diabetes, hypertension, stroke and gall bladder disease, a reduction in the average weight of the general population would improve overall health

(2, 4). The public would benefit from increased availability of food and food products lower in calories, total fat, saturated fat, cholesterol, sodium and sugar. Food manufacturers can contribute to improving the quality of food intake by increasing the availability of palatable, easily prepared products that will help people follow a reduced fat diet. Because the public is becoming increasingly conscious of the role nutrition plays in good health, development of fat substitutes and low fat products should also benefit the food industry (2). FAT CONSUMPTION

AND DIETARY GUIDELINES

Fats, after water and carbohydrates, are the most plentiful nutrient in the typical American diet. Almost all foods contain at least traces of fat, often in the form of invisible oils. Exactly how much fat the average American consumes is open to debate, although experts agree that the majority probably consume too much. Nutrition surveys show that the average fat intake is well above the recommended levels. Although some fat is essential, only a very small amount is needed to meet basic nutritional needs. There is no RDA (recommended dietary allowance) for fats, but as little as one tablespoon a day of fat (polyunsaturated) can provide all of the essential fatty acids the body needs. Most experts agree, however, that more fat than this should be consumed, and there should be a balance of different kinds of fats. Even people who are trying to lose weight should get about 20 percent of their calories from fat. The 30 percent of calories recommended by the American Heart Association and other organizations (for adults and children over the age of two) is probably a more realistic goal. Any benefits of extremely low fat diets, except in unusual circumstances, are unproved and highly controversial (7). Dietary

fats contribute

more than twice as many calories

as equal

DIETARY FAT SUBSTITUTES

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a m o u n t s (by weight) of e i t h e r p r o t e i n or c a r b o h y d r a t e (9 c a l o r i e s per g r a m versus 4 c a l o r i e s per gram). Even t h o u g h excess c a l o r i e s from c a r b o h y d r a t e s and p r o t e i n end up as b o d y fat, a diet rich in fatty food is m o r e likely to r e s u l t in w e i g h t gain. R e c e n t studies also i n d i c a t e that c a l o r i e s f r o m fat m a y be m o r e fully s t o r e d as b o d y fat than c a l o r i e s from c a r b o h y d r a t e s or protein. C a l o r i e s can be b u r n e d at a h i g h e r rate w h e n a p e r s o n c o n s u m e s a h i g h c a r b o h y d r a t e d i e t i n s t e a d of a h i g h fat one (2, 7, 8). In t h e i r S t a t e m e n t for P h y s i c i a n s and H e a l t h P r o f e s s i o n a l s , the N u t r i t i o n C o m m i t t e e of the A m e r i c a n Heart A s s o c i a t i o n r e c o m m e n d e d several d i e t a r y m o d i f i c a t i o n s for all h e a l t h y A m e r i c a n adults. Total fat intake s h o u l d be less than 30 p e r c e n t of the total c a l o r i e s per day. S a t u r a t e d fat s h o u l d be less t h a n i0 p e r c e n t of c a l o r i e s and poly- u n s a t u r a t e d fat should not e x c e e d i0 p e r c e n t of calories. It was also r e c o m m e n d e d t h a t c a l o r i e intake should only be s u f f i c i e n t to m a i n t a i n r e c o m m e n d e d b o d y w e i g h t b a s e d on the M e t r o p o l i t a n T a b l e s of H e i g h t and W e i g h t (3). REGULATORY

ISSUES

A l t h o u g h the p r e v a i l i n g a t t i t u d e of the g e n e r a l p u b l i c is t o w a r d a h e a l t h i e r l i f e s t y l e and diet, there is r e s i s t a n c e to c h a n g e w i t h i n the r e g u l a t o r y and g o v e r n i n g agencies. For w h a t e v e r reasons, the move t o w a r d lower fat foods and the d e v e l o p m e n t of fat r e p l a c e m e n t s or s u b s t i t u t e s has b e e n a s l o w process. Part of the p r o b l e m has b e e n in the r e g u l a t i o n of fat substitutes. T h e r e are t h r e e w a y s for a m a n u f a c t u r e r to a p p r o v e the use and r e g u l a t i o n of fat substitutes. These include: i) c r e a t i n g a new molecule, 2) a p p l y i n g a n e w p r o c e s s to m a k e old m o l e c u l e s serve a new purpose, or 3) e x p a n d i n g upon the use of old p r o c e s s e s a p p l i e d to n e w molecules. If a n e w m o l e c u l e is developed, it m u s t be c l e a r e d as a food a d d i t i v e (Olestra, for example). M i l l i o n s of d o l l a r s and years of d e l a y can be involved. If a n e w p r o c e s s is a p p l i e d to an old molecule, a g e n e r a l l y r e g a r d e d as safe (GRAS) a f f i r m a t i o n p e t i t i o n w o u l d p r o b a b l y be r e q u i r e d by the Food and Drug A d m i n i s t r a t i o n (FDA). This takes a l m o s t as m u c h time and m o n e y as the c l e a r a n c e of a food additive. The a f f i r m a t i o n p r o c e s s also p u b l i c i z e s the t e c h n o l o g y and m a r k e t i n g s t r a t e g i e s of a company. This makes the p r o t e c t i o n of c o n f i d e n t i a l i n f o r m a t i o n v e r y difficult. Both the food a d d i t i v e c l e a r a n c e and a f f i r m a t i o n p e t i t i o n p r o c e s s e s are v e r y long. It is likely by the time the s u b m i t t e d t e c h n o l o g y is a p p r o v e d it will be obsolete. E a c h new, i m p r o v e d t e c h n o l o g y w o u l d have to go t h r o u g h the same procedure. The t h i r d option, e x p a n d i n g on the use of old p r o c e s s e s a p p l i e d to new molecules, is the m o s t used. The c u r r e n t g r o w t h of r e d u c e d - f a t foods a l r e a d y on the m a r k e t is proof of this. Existing technologies and uses of f a m i l i a r m o l e c u l e s are r e f i n e d and e x p a n d e d upon. By g o i n g this route, c o m p a n i e s can avoid the l e n g t h y p r e - c l e a r a n c e r e q u i r e m e n t s of the Federal G o v e r n m e n t (9). The e n a c t m e n t of the N u t r i t i o n L a b e l i n g and E d u c a t i o n A c t (NLEA) of 1990 will s u b j e c t all foods to new l a b e l i n g r e q u i r e m e n t s . Nutrition l a b e l i n g will be m a n d a t o r y on v i r t u a l l y all p a c k a g e d foods except those t h a t are not a m e a n i n g f u l source of n u t r i e n t s and t h o s e

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produced by small businesses. The NLEA requires that nutrition labels include total calories, and the amount of total fat, saturated fat, protein, carbohydrates, and fiber. The new law also states that all foods must have ingredient statements and that claims for nutrient content or diet-disease relationships be defined by regulation. In response to the new law, the FDA has proposed to define nutrient content claims such as fat-free, low-fat, and reduced-fat. Proposals have also been published to permit health claims for a relationship between dietary fats and cardiovascular disease, as well as dietary fats and cancer. Although labeling regulations do not require a specific listing of fat substitutes, the amount of fat substitutes added to foods will effect labeling information. Fat substitutes, like all other ingredients, must be listed in order of predominance in the list of ingredients. The number of calories listed in the nutrition label must equal the digestible calories contained in a serving of food. If an ingredient is nondigestible, the manufacturer must have data to demonstrate the level of digestible calories. The amount of nondigestible fat substitutes, although listed as ingredients, would not be included in total fats. The use of fat substitutes may qualify a food for the label of fat-free, low-fat, or reduced-fat, provided that the product complies with established definitions. Reductions in total fat or saturated fat made possible by the use of fat substitutes may also qualify a product to be labelled with an appropriate health claim (i). SAFETY ISSUES Fat replacements are so new that independent research results on usage, efficacy and safety in broad scale, public diet modification programs are not yet available (i0). It is important to realize that for each new fat substitute, a unique safety evaluation program must be developed, taking into consideration the chemistry and properties of the substance in question. Like other macronutrients, noncaloric fat substitutes need to possess a well-defined product specification that provides assurance of both its chemical stability and its presumed metabolic outcome, and ensures that it is free of potentially toxic impurities. In toxicological studies, the focus must be on the gastrointestinal tract. Factors to be considered include potential adverse effects of unabsorbed fat substitutes on lymphatic and gastrointestinal tissues and bile acids. Researchers must also question what the effect would be of lipid-like fat substitutes on the absorption of fat soluble vitamins and drugs, and the digestion and utilization of macronutrients (ii). Ingredients that are not digested as they proceed through the gastrointestinal tract might contribute to intestinal blockage. Of special concern are substances that have a tendency to clump when changes in moisture or acidity occur. An additional important consideration of nondigested ingredients is their possible laxative effect. This can cause a reduction in the absorption of certain nutrients (i).

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It is a s s u m e d that fat s u b s t i t u t e s will be s e l e c t e d for h i g h usage by i n d i v i d u a l s t r y i n g to lose w e i g h t a n d / o r reduce their r i s k for heart disease. Some of the s a f e t y c o n c e r n s for these h i g h usage people include those m e n t i o n e d above and an i n c r e a s e d c o n s u m p t i o n of p r o t e i n and c a r b o h y d r a t e s r e s u l t i n g in h i g h e r intake of total calories. The e x i s t e n c e of c a l o r i e - f r e e c a r b o h y d r a t e substitutes, as well as fat substitutes, poses the p o s s i b i l i t y of i n c r e a s e d intake of n o n n u t r i e n t foods w h i c h m i g h t have serious h e a l t h c o n s e q u e n c e s . In a d d i t i o n to these p h y s i c a l concerns, there are some p s y c h o l o g i c a l issues to consider. W h a t effect, if any, will these fat s u b s t i t u t e s h a v e on e a t i n g - d i s o r d e r e d p e o p l e or on the b e h a v i o r m o d i f i c a t i o n of dieters? Will f a t - s u b s t i t u t e d foods s a t i s f y the p s y c h o l o g i c a l craving for fat (i, i0, ii)? IMPACT W h e n an individual c o n s u m e s a f a t - s u b s t i t u t e d food in an e f f o r t to m o d i f y the fat in t h e i r diet, do t h e y u n c o n s c i o u s l y add fat and/or c a l o r i e s b a c k into their diet? One s t u d y done in 1982 by G l u e c k et al. r e p o r t e d only partial c a l o r i e r e p l a c e m e n t u s i n g s u c r o s e p o l y e s t e r (SPE) as the fat s u b s t i t u t e (20 to 25 p e r c e n t of the calories) c o m p a r e d to the control g r o u p (35 to 40 percent). T h e y also found this s u b s t i t u t i o n to be e f f e c t i v e in m o d i f y i n g s e r u m lipids (12). Conversely, w i t h a d e c r e a s e in fat, there m i g h t be a c o m p e n s a t o r y increase in c a r b o h y d r a t e and p r o t e i n (13). Therefore, the use of fat s u b s t i t u t e s in foods does not n e c e s s a r i l y make the total d i e t a r y intake lower in calories. C o n s u m e r e d u c a t i o n plays a key role in the e f f e c t i v e use of these foods in a w e i g h t control regimen. Without p r o p e r e d u c a t i o n about d i e t a r y fats, p a t i e n t s are likely to m a k e i n c o r r e c t s u b s t i t u t i o n s for h i g h fat foods. CHARACTERISTICS

OF FAT

Why does the a v e r a g e A m e r i c a n diet d e r i v e 37 p e r c e n t of total calories from fat? W h y are fats so d i f f i c u l t to give up? American e a t i n g h a b i t s h a v e b e e n c h a n g e d by several factors, such as the increase of w o m e n in the w o r k force, a m o r e casual lifestyle, m o r e after school and e v e n i n g activities, and h i g h e r d i s p o s a b l e incomes. The variety, a v a i l a b i l i t y and a f f o r d a b i l i t y of c o n v e n i e n c e and fast foods have i n c r e a s e d d r a m a t i c a l l y , and m a n y of these foods c o n t a i n large a m o u n t s of fat. F a s t food e n t r e e s often c o n t a i n 40 to 50 p e r c e n t of their c a l o r i e s from fat b e c a u s e of the i n c l u s i o n of h i g h fat i n g r e d i e n t s and the f r e q u e n t use of frying (4). The n u t r i t i o n a l role of fats is to p r o v i d e a c o n c e n t r a t e d source of e n e r g y and to s u p p l y e s s e n t i a l fatty acids and fat soluble v i t a m i n s to the d i e t (14). The p r e f e r e n c e for h i g h fat foods, however, relates m o r e to the s e n s o r y p r o p e r t i e s of fats w h i c h give foods t h e i r a p p e a l i n g flavor, aroma and t e x t u r e (4, 14, 15). Fat also effects crispness, tenderness, body, s m o o t h n e s s and a p p e a r a n c e of a product. It c o n t r i b u t e s to the m o i s t n e s s and rich m o u t h f e e l of foods (16). Fats in foods p r o v i d e a w i d e v a r i e t y of oral sensations. Smoothness in ice c r e a m comes from d a i r y fat w h i c h p r e v e n t s the f o r m a t i o n of large ice crystals. The s e n s a t i o n of f r e s h n e s s and m o i s t u r e in b a k e r y goods r e s u l t s f r o m the w a t e r - b i n d i n g p r o p e r t i e s of fats. The m a r b l i n g of m e a t c o n t r i b u t e s to its tenderness. C r i s p or c r u n c h y t e x t u r e s in p o t a t o chips or fried p o t a t o e s are d e r i v e d from frying in fat w h i c h brings foods to t e m p e r a t u r e s above the b o i l i n g point of water. R e m o v i n g the fat from food r e d u c e s the oil s o l u b l e flavor

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sensations and alters the perception of fat. Texture can also be greatly influenced by the fat content of foods. Cookies and crackers made without fat tend to be stiff and difficult to handle. Low fat meats and cheese toughen if they are heated. When describing foods, people often use key words defining the texture, such as hard, soft, juicy, chewy, oily, greasy, viscous, slippery, elastic, flaky, creamy, crisp, crunchy, and brittle, rather than terms describing taste or flavor (14, 17). ~AT REPLACERS In order to effectively mimic fat, a fat substitute must produce the perception of all the above attributes. Reducing the particle size of a fat substitute, for example, can create the impression of creaminess and enhance the perception of fat. Hydrocolloids can give a creamy mouthfeel to salad dressings and can be used as stabilizers in frozen desserts. Many of the fat-reduced products on the supermarket shelves are the result of commercial techniques of heating, acidifying, and blending common food ingredients, such as carbohydrates, milk and egg proteins, and/or water, to copy the texture of fat. Other processes use enzymes to produce fat-free products similar in taste and texture to the high fat original. If standard ingredients and processing methods are used, their incorporation into the food supply does not require FDA approval. Examples of products in which such ingredients or processing methods are used include cheese, processed cheese products, fat-free bakery goods, frozen desserts, and yogurt. The primary categories of fat replacers differ in their physiological effects. Most of the carbohydrate and protein-based substitutes are partially or fully digested and absorbed. They still produce a lower calorie product because of their low energy density. The lipid-based replacers are resistant to digestive enzymes and are largely excreted with minimal change. These are the four general categories of fat substitutes that will be discussed: i) carbohydrate-based, 2) protein-based, 3) fat-based, and 4) mixed blends. The types, properties, functions and applications in food products for each category will be reviewed. CARBOHYDRATE-BASED FAT SUBSTITUTES: The carbohydrate-based fat substitutes include polydextrose, altered sugars, starch derivatives, and cellulose and gums (see Table i). They can also be made from rice, wheat, corn, oats, tapioca or potato, and can replace from 50 to i00 percent of the fat in foods (17). Polydextrose is made of glucose polymers, sorbitol and citric acid. It was developed initially as a bulking agent to be used with nonnutritive sweeteners (Litesse) and can be used to maintain texture, body and mouthfeel usually associated with sugar and fat in a variety of low calorie products (18). It was approved as a food additive by the Food and Drug Administration in 1981. Polydextrose can also be used as a humectant to replace sugar or fat in baked goods and mixes, chewing gum, salad dressings, frozen desserts, gelatins, puddings, candies, confections and frostings. It may replace up to one half of the fat in a food product.

DIETARY FAT SUBSTITUTES TABLE CARBOHYDRATE-BASED

I

CATEGORY Starch

NonStarch

TYPE

1 FAT REPLACERS

SOURCE/ MISC.

FOR USE IN:

IPolydextrose

Modified Glucose Polymers

Bakery Goods, Candy, Frozen Desserts, Dairy Products

Starch Derivatives

Modified Tapioca, Corn, Potato, Rice Starches

Altered Sugars

Cellulose and Gums

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Cakes, Cheese, Sour Cream, Dairy Desserts, Frozen Dairy Desserts, Salad Dressings, Margarine

Inulin

S u g a r and/or Fat Replacers; Frozen Desserts, Candy, Bakery Goods

(Bulking Agent)

Salad Dressings, Bakery Goods, Cheese, Frozen D a i r y Desserts, Meat, Icings

KCAL/I GRAM

1-4

Polydextrose has high stability. It has a caloric value of 1 kilocalorie (kcal) per gram which means it contributes 25 percent of the caloric value of sucrose or ii percent of the energy of fat. A drawback of this substitute is the laxative effect when consumed in large quantities. Studies show that polydextrose does not interfere with absorption or utilization of essential vitamins, minerals or amino acids. Polydextrose improves the mouthfeel and viscosity of food products. Because it can absorb moisture, polydextrose is used in dry mixes to prevent lumping. Polydextrose is currently being used in bakery goods and baking mixes. It lowers the calories in these products while improving textural qualities without the use of sucrose. This fat substitute is also used in hard and soft candies and in frostings to partially replace either sugar or fat. One of the problems encountered when modifying the sugar and fat content of frozen desserts and dairy products is the altered freezing point. The use of polydextrose as a substitute counteracts this effect. It also contributes to the creamy, smooth mouthfeel of the product. Polydextrose cannot be used in yeast breads if all the fermentable sugars are replaced unless enzymes are added. It is also not suitable for use at very high temperatures as in deep frying. Altered Sugars are another type of carbohydrate-based fat substitute. While polydextrose is a nonsweet starch polymer, the altered sugars provide some sweetness and other properties of sucrose. Strictly speaking, they are fibers but their use is similar to that of a sugar and/or fat substitute. Inulin is the altered sugar to be discussed here because it is used as a fat substitute as well as a sugar replacer. It is refined from

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tubers and has a s w e e t e n i n g power 30 to 65 p e r c e n t m o r e than sucrose. Inulin's e f f e c t on f r e e z i n g point is s i m i l a r to glucose. It has b e e n u s e d in ice c r e a m as a r e p l a c e m e n t for b o t h sugar and fat t h e r e b y r e d u c i n g the c a l o r i e s by m o r e t h a n 50 percent. It c o u l d also be u s e d in c a n d y and b a k e r y products. Starch derivatives include m a l t o d e x t r i n s , dextrins and m o d i f i e d starches. T h e y are used as e i t h e r sugar or fat replacers. M a l t o d e x t r i n s and d e x t r i n s are m e t a b o l i z e d s i m i l a r l y to s t a r c h and can be u s e d by diabetics. S u b s t i t u t e d on an equal w e i g h t basis, t h e y p r o v i d e 4 k i l o c a l o r i e s per g r a m (kcal/g). W h e n r e p l a c i n g fat only, t h e y are m i x e d w i t h w a t e r p r o d u c i n g a gel w i t h less t h a n 1 kcal/g. These fat s u b s t i t u t e s are u s e d in a v a r i e t y of p r o d u c t s p e r f o r m i n g a w i d e range of functions. These include bulking, r e s i s t a n c e to caking, a d d i n g t e x t u r e and body, f o r m i n g films, b i n d i n g flavor and fat, a d d i n g n u t r i t i v e value, s e r v i n g as o x y g e n b a r r i e r s and a i d i n g d i s p e r s i b i l i t y and s o l u b i l i t y (17). S t a r c h d e r i v a t i v e s have a low s w e e t n e s s level and a b l a n d f l a v o r t h a t w o n ' t m a s k other flavors. P r o c e s s i n g t h e m to m a i n t a i n small, s w o l l e n starch g r a n u l e s is t h o u g h t to be one m e t h o d to d u p l i c a t e the m o u t h s e n s a t i o n of fat. M a l t o d e x t r i n s can be u s e d as fat or sugar r e p l a c e r s in b a k e r y goods. Their role appears to be p r i m a r i l y w a t e r - b i n d i n g . As a r e p l a c e m e n t for m i l k f a t in cheeses, sour creams and d a i r y desserts, m a l t o d e x t r i n s w o r k well b e c a u s e t h e y m i m i c the m o u t h f e e l and c o n s i s t e n c y of the fat. A v a r i e t y of m a l t o d e x t r i n gels are u s e d in r e d u c e d - f a t frozen d a i r y desserts. These are e f f e c t i v e s u b s t i t u t e s in frozen food p r o d u c t s in part because, again, t h e y p r o d u c e a s i m i l a r m o u t h f e e l to that of milkfat. M a l t o d e x t r i n s r e p l a c e oils in salad dressings, dips and i m i t a t i o n mayonnaise. In these products, the fat s u b s t i t u t e s u s e d g i v e the t e x t u r e of the oil but o n l y one third of the calories. In margarine, m a l t o d e x t r i n s give the flavor, m o u t h f e e l and s p r e a d i n g p r o p e r t i e s of a soft m a r g a r i n e w i t h about half of the calories. Cellulose a n d g u m ~ are the last c a t e g o r y of c a r b o h y d r a t e - b a s e d r e p l a c e r s to be discussed. Gums can p r o v i d e the b u l k i n g p r o p e r t i e s of sugar and fat and can be u s e d as a p a r t i a l r e p l a c e m e n t for flour to h e l p r e d u c e calories. In addition, gums have p o t e n t i a l h e a l t h b e n e f i t s by p r o v i d i n g d i e t a r y fiber. C e l l u l o s e is white, tasteless, and has little or no food energy. C o l l o i d a l grades, such as Oatrim, p r o d u c e a gel t h a t works well as a fat substitute. O a t r i m is b e i n g u s e d in foods c u r r e n t l y on the market, i n c l u d i n g cookies, muffins, f a t - f r e e cheese, extra lean g r o u n d beef, bologna, and hot dogs. It c o n t r i b u t e s body, stability, creaminess, m o u t h f e e l and the g l o s s y a p p e a r a n c e of high fat. In some applications, cellulose is not technically a "fat substitute". W h e n u s e d as a c o a t i n g and b a t t e r for foods t h a t are d e e p fried, it r e d u c e s the oil a b s o r p t i o n t h e r e b y r e d u c i n g the fat content. Flour

derivatives

and rice,

wheat,

corn,

oat,

and p o t a t o

have b e e n

DIETARY FAT SUBSTITUTES

1613

used as fat replacers in items as diversified as meat products replacing some of the fat. Flavoring systems are added to improve consumer satisfaction. Starches, such as tapioca, have also been used as "extenders" in meat products. Gums (guar, locust bean, xanthan, etc.) are frequently used in low levels to provide viscosity to foods. They are used as thickening agents in sauces and puddings or contribute viscosity in sugar-free beverages and light (reduced sugar) syrups. Gums are often used to provide functional properties of fat when water is used to replace fat in foods. They are also added to the dry ingredients in bakery products as bulking agents (carrageenan, for example). Locust bean, guar and xanthan gums are used as stabilizers in whipped products, cake batters and pourable salad dressings. Gums are not digested except by bacteria in the lower intestine so their calories are negligible (16, 17). PROTEIN-BASED FAT SUBSTITUTES: TABLE 2 PROTEIN-BASED REPLACERS I

liso cE Milk Solids

FOR USE

OIS V ^G

KC IG--il

Dairylight Frozen Desserts, Not

Corn Protein Lita

1.5

Dairy Products, suitable Egg White and Milk Protein

simplesse

Margarine, for

1-2

Mayonnaise, frying Salad Dressing

Whey Protein

simplesse i00

Some of the sources for the modified protein fat substitutes are milk, corn, egg white and whey (see Table 2). The proteins are prepared using physical aggregation without chemical breakdown so the nutritional value is retained. These substitutes can replace 75 to i00 percent of the fat. Because the modified proteins have uniformly small particles called "ball bearings", they are perceived as a creamy fluid. Modified proteins make suitable substitutes for fat in dairy products, including frozen desserts, margarine, salad dressings and mayonnaise. Proteins are subject to heat denaturation so the replacers made from egg whites change when exposed to heat in food processing. The substitutes made from whey and corn proteins are more suitable for use in products requiring heat, but not the extreme heat of fried foods. Simplesse, a low calorie protein-based fat substitute, was introduced in 1988. The FDA confirmed GRAS status in 1990. Simplesse is produced from milk and/or egg protein by a heating and blending process called "microparticulation". Proteins coagulate as they are heated. Normally, heat-coagulated proteins form large particles of

1614

C.J. GLUECK et al.

gel which feel rough in the mouth. The microparticulated process shapes the protein gel into particles so small that the tongue sees them as fluid and feels the richness and creaminess associated with fat. By using Simplesse, 1 gram of protein (4 kcal/g) and 2 grams of water replaces 3 grams of fat (9 kcal/g). This means that 27 calories from fat are replaced with 4 calories from protein. Simplesse can be used for frozen desserts, yogurt, cheese spread, cream cheese, sour cream and coffee creamer, as well as oil-based products such as salad dressing, mayonnaise and margarine. Simplesse can not be used in cooking oils or in foods that require frying. The high heat level would cause the proteins to coagulate which would destroy the fat-like mouthfeel (19, 20). Some lower heat baked items such as pizza, lasagna and cheesecake, however, can be prepared from cheeses made with Simplesse (16). Three forms of Simplesse are currently available. These include Simplesse i00, an opaque, viscous fluid, simplesse Dry i00, a white free-flowing powder that can be easily rehydrated, and Simplesse 300, a viscous, plastic-like fluid (18). Although there is no evidence to suggest that Simplesse produces adverse effects in normal persons, anyone allergic to milk or eggs should avoid it (21). Recent studies (22, 23) have shown that the microparticulated process does nothing to destroy the allergenic components of cows' milk and egg. It is important that food products containing microparticulated proteins, such as simplesse, be clearly labelled to indicate the presence of egg white and cows' milk, and that food-allergic patients be advised of the composition of Simplesse. If Simplesse were used exclusively in all potential applications, it would replace about 14 percent of total dietary fat intake. This would reduce total fat intake, currently at about 37 percent of calories, to about 32 percent of total calories. It would, however, increase protein intake from 16 percent to 17 percent of caloric intake, and carbohydrate from 48 percent to 52 percent of caloric intake (23). LIPID-BASED AND MIXED BLEND REPLACERS: Both lipid-based and mixed blend fat replacers are either emulsifiers or fat analogs that have been modified or synthesized so that they are no longer metabolized completely (see Table 3). Chemically altered lipids provide fewer calories because they are not metabolized and they can be used in high temperature applications such as frying (17). They can replace 35 to i00 percent of the fat. Caprenin is derived from glycerol and a mixture of synthetic fatty acids (21). It uses a less digestible fatty acid to replace one of the more digestible ones. Because it is only partially absorbed, Caprenin supplies 5 kcal per gram instead of 9 kcal per gram for other dietary fats. Caprenin is very similar to cocoa butter and is intended to replace it in soft candy and chocolate confectionery coatings. It has FDA GRAS approval and is currently being used in

DIETARY FAT SUBSTITUTES

1615

TABLE 3 LIPID-BASED & MIXED BLEND REPLACERS

EXAMPLE Fat Derivatives

Fat Extenders

FOR USE IN:

NOTE

Caprenin

Replaces cocoa butter in soft candy

Currently used in Milky Way II candy bars

Olestra

Replaces oil & shortening in baking and deep fat frying

Not yet approved

Emulsifiers

Bakery Goods, Frozen Desserts

KCAL/GM JJ

Calories same as fat but less used thus fewer calories

a candy bar (16, 17, 24, 25). Olestra, formerly called sucrose polyester (SPE), is a substitute for fat made of a mixture of fatty acids derived from edible oils such as soybean, corn and cottonseed, and a sucrose core that is common table sugar. It does not hydrolyze in the presence of pancreatic lipase. It has the physical and culinary properties similar to dietary fats but is totally non-absorbed. It can be used in place of standard fats and oils (4, 26). As shown in a placebo-controlled study with hypercholesterolemic outpatients, the addition of SPE to the diet can produce small reductions in both total and LDL cholesterol. Additional studies have shown significant reductions in total and LDL cholesterol by using SPE as a substitute for conventional dietary fat (27). Unlike gums, modified starches, and microparticulated proteins, which are used to preserve the mouth feel properties of reduced-fat foods but are destroyed by heat, Olestra can be used in cooking. It has the capacity to serve as a non-caloric fat replacement with a wide range of potential uses (15). It is a good candidate as a cooking "oil" for potato chips, French fries, and other fried favorites. The proposed levels of substitution are up to 35 percent of the fat used in shortenings and cooking oils for home use and up to 75 percent of the fat used in commercial deep-fat fryers and in fried snack foods (21, 28). Many laboratory studies and clinical investigations have been completed to date. Because Olestra is not absorbed or metabolized by humans, it does not appear to be toxic, carcinogenic or mutagenic. Rat studies during growth, mating, and gestation showed no effect on fertility and no birth defects. Olestra consumption did not interfere with the absorption of macronutrients, minerals, vitamins or medications, including aspirin, diazepam, and propranolol, or lipophilic drugs such as oral contraceptives (4). There are questions, however, that Olestra may inhibit the absorption of vitamin E. Consideration is being given

1616

C.J. GLUECK et al.

to fortifying olestra with small amounts of this vitamin

(21).

Emulsifiers and emulsified blends have been suggested for use as fat extenders. Their calorie content is the same as fat, but because 25 to 78 percent less is needed to produce fat-like characteristics, the calories decrease. These emulsifiers cost less than fats, retain moisture and increase volume in food products. They are currently being used in bakery products and frozen desserts. MIXED BLENDS: TABLE 4 MIXED BLENDS EXAMPLES

FOR USE

IN:

Carrageenan and Dairy Protein

Bindex

Meats

Emulsion of Fat with Polydextrose

Veri-Lo with Litesse

Fat and sugar replacers; misc. products

Egg Albumen and Xanthan Gum

Trailblazer

Fro2en Desserts

Most of these blends were reviewed as individual fat substitutes. Combinations of fat substitutes, such as sucrose polyester mixed with protein, have applications in frozen desserts, salad dressings, margarine, sauces, snacks and bakery goods. Carrageenan, combined with dairy protein, can be used in low fat meats (see Table 4) (17). SUMMARY The effectiveness of any fat replacer is reflected in its sensory properties. The appearance, mouthfeel, and flavor of the altered product must at least be acceptable. The product must also be stable with good shelf-life. As these fat-free and lower-fat foods become increasingly available, the potential exists to help people significantly moderate their fat intake. It has been proposed that incorporating these foods into the average diet would reduce the fat intake f r o m the current 37 percent to the recommended 30 percent of total energy (16, 23). But for all the potential benefits, there are potential risks. These fat replacements are so new that only relatively limited long term, large scale human ingestion data are currently available. The reduction of fat projected with the use of these fat replacers could have a modest impact on the level of obesity. But how effective these low calorie, low fat foods will be on weight control when part of an overall weight control program remains to be seen. It has yet to be determined whether the fat substitutes will be able to satisfy the psychological need for fat and whether a diet including these

DIETARY FAT SUBSTITUTES

1617

replacers will stimulate any digestive and/or appetite mechanisms that will result in food cravings. The long term impact of fat replacers in people's diets includes some other concerns. The use of the protein-based fat replacers may increase the protein intake in a diet already too high in protein, posing a risk for kidney disease in some susceptible subjects (i0). Large scale introductions of fat substitutes into foods may have unanticipated effects on food selection and nutrient intake. Consideration for these issues should focus on groups with special dietary needs (children and the elderly) or those who might be expected to incorporate fat-substituted foods into their diets at high levels (teenage girls). Although, in general, fat substitutes appear to pose little risk, there is too little data to verify the possible benefits under conditions of normal consumer use (29). The American Dietetic Association emphasizes the need for public education in the appropriate use and amounts of these foods. The principles of balance, variety, and moderation should apply to the use of all foods, regardless of their nutrient profile. Guidelines for daily food consumption should emphasize nutrient-rich foods, including whole grains, fresh fruits and vegetables, while limiting intake of fats, sweets and alcohol. The American Dietetic Association further encourages manufacturers of reduced-fat and fat-free foods to participate in nationwide education efforts to help Americans safely and expeditiously implement dietary recommendations that promote optimal health throughout life (16). REFERENCES i.

Vanderveen JE, Glinsmann WH. Fat substitutes: A regulatory perspective. Annu Rev Nutr 1992; 12:473-487.

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Nutrition Committee, American Heart Association. Dietary guidelines for healthy American adults, circulation 1988; 77:721A-724A.

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Ruoff GE. Reducing fat intake with fat substitutes. Physician 1991; 4443:1234-42.

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Summary of the Second Report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel II). JAMA 1993; 269:3015-23.

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Harris RB. Growth measurements in Sprague-Dawley rats fed diets of very low fat concentration. J Nutr 1991; 121: 1075-80.

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Brown WV. Fats and cholesterol. In: Herbert V, Subak-Sharp G, eds. The Mount Sinai School of Medicine Complete Book Of

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Harris RB. Physiological response of mature rats to replacement of dietary fat with a fat substitute. J Nutr 1991; 121:1109-16.

9.

Thompson MS. Issues associated with the use and regulation fat substitutes. Crit Rev Food Sci Nutr 1992; 32:123-6.

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i0. Foreyt JP, Goodrick GK. Potential impact of sugar and fat substitutes in American diet. Journ Natl Cancer Inst Monogr 1992; 12:99-103. ii. Munro IC. Issues to be considered in the safety evaluation fat substitutes. Fd Chem Toxic 1990; 28:751-3.

of

12. Glueck CJ, Hastings MM, Allen C, Hogg E, Baehler L, Gartside PS, Phillips D, Jones M, Hollenbach EJ, Braun B, Anastasie JV. Sucrose polyester and covert caloric dilution. Am J clin Nutr 1982; 52:969-81. 13. Beaton GH, Tarasuk V, Anderson GH. Estimation of possible impact of non caloric fat and carbohydrate substitutes on macronutrient intake in the human. Appetite 1992; 19:87-103. 14. Drewnowski A. Sensory properties Nutr Rev 1992; 50:17-20.

of fats and fat replacements.

15. Rolls BJ, Pirraglia PA, Jones MB, Peters JC. Effects of Olestra, a noncaloric fat substitute, on daily energy and fat intakes in lean men. Am J Clin Nutr 1992; 56:84-92. 16. Hudnall MJ, Connor SL, Connor WE. Position of The American Dietetic Association: Fat Replacements. J Am Diet Assoc 1991; 91:1285-8. 17. Setser CS, Racette WL. Macromolecule replacers in food products. Crit Rev Food Sci Nutr 1992; 32:275-97. 18. Pszczola DE, ed. New ingredients 1992 January; 129-48. 19. Anonymous.

Fat substitute

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and applications.

Food Tech 1990 March;

20. Lynch PM. Sugar and fat substitutes: The challenge and tomorrow. Diabetes Educ 1990; 16:101-5. 21. Cerrato PL. Fat substitutes-a

Food Tech

closer

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92-7.

for today

56:67-70.

22. Sampson HA, Cooke S. The antigenicity and allergenicity of macroparticulated proteins: Simplesse. Clin Exp Allergy 1992; 22:963-9. 23. Gaull GE. Role of microparticulated protein fat substitutes food and nutrition. Ann N Y Acad Sci 1991; 623:350-5. 24. Webb DR, Sanders RA. Caprenin i. Digestion, absorption, and rearrangement in thoracic duct-cannulated rats. J Am Coll Toxicol 1991; 10:325-39. 25. Peters JC, Holcombe

BN, Hiller LK, Webb DR.

Caprenin

3.

in

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Absorption and caloric value in adult humans. J Am Coll Toxicol 1991; 10:357-67. 26. Jandacek RJ, Ramirez MM, Crouse JR. Effects of partial replacement of dietary fat by Olestra on dietary cholesterol absorption in man. Metabolism 1990; 39:848-52. 27. Glueck CJ, Jandacek R, Hogg E, Allen C, Baehler L, Tewksbury M. Sucrose polyester: substitution for dietary fats in hypocaloric diets in the treatment of familial hypercholesterolemia. Am J Cli Nutr 1983; 37:347-54. 28. The American Dietetic Association. Sports and Cardiovascular Nutritionists. Diet and CHD: Summary of the literature: Fat replacement. In: Kris-Etherton PM, Volz-Clarke P, Clark K, Dattilo A, eds. Cardiovascular Disease: Nutrition For Prevention and Treatment. American Dietetic Association, 1990; 48-50. 29. Mela DJ. Nutritional implications of fat substitutes. J Am Diet Assoc 1992; 92:472-6.

Accepted for p u b l i c a t i o n January 7, 1994.