Polyols: Benefits Beyond Sweet Taste, Part 1

Weight-loss and weight-management products continue to be potent market contenders, as consumers report a desire for a greater variety of low- and reduced-calorie foods from which to choose. A group of reduced-calorie sweeteners known as polyols, or sugar alcohols, can assist in reducing the calories of foods and beverages to meet the strong consumer demand for these lighter foods and beverages.

In addition to their use in the production of low- and reduced-calorie foods, polyols are increasingly utilized for their functional benefits. This trend in increased usage reflects the wide range of benefits these bulk sweeteners offer for food production and food-product design. Polyols bring benefits to consumers that extend beyond sweet taste.

Investigating the basics 

Polyols are neither sugars nor alcohols. They are a group of low-digestible carbohydrates, which are similar in structure to sugar molecules, except for the substitution of a hydroxyl group in place of the aldehyde group found on sugars. This substitution is the reason polyols are commonly referred to as sugar alcohols. The substitution of a single hydroxyl group preserves enough of the chemical structure of sugar to give polyols many of the physical properties of sugars, so that polyols can often replace sugar and corn syrups in many food and beverage applications.

Many of the properties are analogous to the sweeteners they are derived from. However, structural differences impart unique functional and health benefits to polyol-containing products vs. their sugar conter-parts.

Polyols are generally made by the hydrogenation of sugars and sugar syrups. Erythritol is produced by fermentation. Polyols are used commercially in both foods and pharmaceuticals. In food applications, they are considered bulk sweeteners, as they can be used volume-for-volume (with the addition of high-intensity sweeteners to increase the sweetness, if needed) in place of sucrose or corn syrups. This is why polyols serve as useful alternatives to sugars in a wide range of products, including chewing gums, candies, ice cream, baked goods and fruit spreads. In addition, they function well in fillings and frostings, canned fruits, beverages, yogurt and tabletop sweeteners. They are also used in toothpastes, mouthwashes and pharmaceutical products, such as cough syrups and throat lozenges.

The term polyglycitols actually represents a wide range of products equivalent to the entire range of corn syrups and maltodextrins. Eight polyols are available for use in the United States: erythritol, polyglycitols or hydrogenated starch hydrolysates (HSH), isomalt, lactitol, maltitol, mannitol, sorbitol, and xylitol. Xylitol is approved for use in special dietary foods, mannitol has interim food additive status, and sorbitol has been affirmed GRAS by FDA. Erythritol, isomalt, lactitol, maltitol and polyglycitols are all self-affirmed GRAS.

Polyols may be listed in the Nutrition Facts panel on food labels as sugar alcohols or, if only one polyol is present in the product, by the specific name of the polyol. Listing in the Nutrition Facts panel, however, is voluntary, except when a claim is made about polyols or sugars when polyols are present in the product.

Digesting the message 

The body metabolizes polyols differently than sugars, with differences among the individual polyols themselves. Due to their unique molecular structure, polyols are incompletely absorbed by the body, with the exception of erythritol. Portions of the polyols that are absorbed are either metabolized (generally by insulinindependent mechanisms) or excreted via urine. In the large intestine, bacteria metabolize a significant amount of the unabsorbed portion into short-chain fatty acids and gases. Erythritol is completely absorbed and excreted unchanged.

Incomplete absorption may cause some people to experience gastrointestinal symptoms, including laxative effects, similar to reactions to beans, cabbage and certain high-fiber foods. Such symptoms are dependent upon an individuals sensitivity and the other foods eaten along with the polyol-containing product. Any gastrointestinal symptomssuch as a feeling of fullness or laxationfrom consuming foods with polyols, if they occur at all, are usually mild and temporary.

The degree of the laxation effect of the individual polyols varies. The statement excess consumption may have a laxative effect is required on the label of a food whose daily consumption might exceed 20 grams of mannitol or 50 grams of sorbitol. The statement is not required on xylitol-containing products. Since regulations have not been codified for the other polyols, they require no such statement. However, food manufacturers are advised to inform consumers of possible gastrointestinal effects through appropriate product labeling.

Multiple health benefits 

With current consumer demand for low-calorie, sugar-free products, as well as the increased availability of polyols and innovations in food technology, additional good-tasting sugar-free and reduced-calorie products are expected to be available. In addition to their clean, sweet taste and unique functional properties, polyols offer important health benefits. For example, they are reduced in calories and do not cause sudden increases in blood sugar levels.

Due to their different metabolic fate, polyols provide significantly less than the traditional four calories per gram assigned to carbohydrates in general. Because they are metabolized differently, the caloric contribution varies by the specific sweetener. FDA allows the use of caloric values shown for the various polyols in Table 1.

A significant body of data suggests that slowly absorbed carbohydrates may have health advantages over those that are rapidly digested and absorbed.

Polyols, for example, elicit a reduced glycemic response and reduce the glycemic load of the diet. Polyols and associated specialty carbohydrates, therefore, can have a useful role in reducing the overall glycemic load of the diet and, in so doing, may help to reduce the risk of a variety of lifestyle-related diseases. (See Glycemic Response, in the July 2006 special supplement of Food Product Design, or on the web at www.foodproductdesign.com/articles/671sup3.html, for more information about glycemic response and polyols effect.) In addition to calorie control, polyols are not readily converted to acids by bacteria in the mouth that cause plaque buildup and dental caries. Thus, FDA has authorized the use of the does not promote tooth decay health claim for sugar-free food products sweetened with polyols (21 CFR 101.80). The American Dental Association, Chicago, has adopted a position statement recognizing the role of sugarfree foods and medications in maintaining good oral health.

Research has shown that polyols and polyol-containing products offer significant health benefits to consumers. Among the major health benefits, the use of polyols may assist consumers in maintaining good oral health, maintaining or reducing weight, and reducing total glycemic load of their diets.

In addition to the health benefits, polyols provide numerous functional benefits to foods, including improved sensory characteristics such as flavor and mouthfeel, increased temperature stability, enhanced moisture control, precise crystallization properties and longer shelf stability. These will be discussed in Part 2 of this article, scheduled for publication in the Oct. 2007 issue of Food Product Design. 

Robin Steagall, R.D., L.D., M.S.P.P.M., serves as manager of nutrition communications for the Calorie Control Council. After completing a degree in industrial management at North Carolina State University and a masters degree in public policy and management at Carnegie Mellon University, she received a degree in dietetics from Georgia State University. Her current responsibilities include crisis management, public relations and communicating the Councils messages on health, fitness and weight management. 

Lyn Nabors, B.S., president, Calorie Control Council, serves in leadership, strategic and administrative capacities for the Council, especially scientific and health issues. She has spearheaded many of the Councils activities on health, fitness and weight management. Editor of Alternative Sweeteners, a textbook on a broad range of sweeteners, she also has authored numerous book chapters and journal articles on low-calorie foods and beverages, sweeteners and fat replacers. She is a Phi beta Kappa graduate of the University of Kentucky with a degree in Public Health. 

For more information on polyols, visit the Calorie Control Councils website, www.caloriecontrol.org, and its polyol website, www.polyol.org.