The secret garden: digestive health is built upon the existence of intestinal microflora that require sustenance from prebiotic ingredients. However, regardless of the nutritional reality, if consumer education is not cultivated, consumers are unlikely to reap their bountiful benefits

Prepared Foods, August, 2005 by Marcia A. Wade

"In the antiseptic American culture, talking about healthy bacteria is an oxymoron," says Wendy Reinhardt Kapsak, MS, RD, director of health and nutrition at the International Food Information Council (IFIC, Washington). "Unaided, consumers do not mention prebiotics as a healthful ingredient; however, they do mention whole grain and other fibers as components beneficial to digestive health, likely because those foods are grounded in long-held associations," she says. She was summarizing findings from IFIC's May 2005 survey, "Consumer Attitudes toward Foods for Health."

A prebiotic is a non-digestible food ingredient that benefits the host by selectively stimulating the growth and/or activity of one or a limited number of bacteria in the colon and, thus, improves host health (Gibson, G.R. and Roberfroid, M.B. 1995. Journal of Nutrition). Some of the more common commercially available prebiotics are resistant maltodextrin, polydextrose and inulin. Prebiotics are fermented by bacteria into short-chain fatty acids (SCFA), the proliferation of which decreases pH.

"Prebiotics benefit both the bacteria in the product and in the colon," explains Hilary Hursh, a food and nutrition scientist at an inulin supply house. A study conducted by her company measured the viability and vitality of bacteria in symbiotic products (products containing both prebiotics and probiotics) using simulated digestion. In such products, more bacteria survived through the product's shelflife and simulated digestion, she summarizes.

Prebiotics have been shown to boost immunity, produce natural antibiotics and help decrease toxic substances in the body. Certain studies suggest inulin prevents the formation of colon cancer. In addition, prebiotics aid in overall digestive health by preventing the growth of pathogens and decreasing recovery time after diarrheal diseases.

Prebiotics help increase the concentration of SCFAs (by-products of fermentation), which, in turn, lowers the colonic pH. The lower pH is theorized to help increase the amount of soluble calcium that can be absorbed by the body. Also, inulin has reportedly stimulated beneficial bacteria that help mediate carbohydrate and lipid metabolism, reducing levels of LDL ("bad") cholesterol.

"Just talking about prebiotics does not help [promote] digestive health, because pre- and probiotics go hand in hand," says Reinhardt Kapsak. The popularity of probiotic products like Lifeway Foods' (Morton Grove, Ill.) kefir has helped gain awareness of digestive health. In fact, more probiotic products are now incorporating prebiotics. Although there is no official definition of probiotics for regulatory purposes, the Food and Agriculture Organization of the United Nations (FAO) defines probiotics as "live micro-organisms which, when administered in adequate amounts, confer a health benefit on the host."

Five years ago, Julie Smolyansky, president of Lifeway Foods, became aware of prebiotics and, in early 2005, decided to add inulin to Lifeway's low-fat and organic lines. "I expect that it is going to be a positive addition to Lifeway because it is a value-added nutrient that doesn't affect the taste or formulation of my products," considers Smolyansky.

Microflora Meals

Most prebiotics can be added to bread, ice cream, yogurt or meat. They generally are very soluble in water and can be added to water without producing any taste or appearance. They are very versatile and can be incorporated into any food product. "Consumers are looking to baked goods, but we have worked on confections, hard candy and chocolate as a novel way to supply people with prebiotic benefits," offers Hursh.

Polydextrose has been on the market for 25 years and has a proven history of use in a variety of food applications. Without having any sweetness, it can be used in combination with a high-intensity sweetener if sweetness is desired, and it is easy to incorporate at higher levels due to its neutral taste.

Compared to some other prebiotics, polydextrose is beneficial, as it is fermented throughout the entire length of the colon. Fermentation in the distal (or latter) part of the colon has been pinpointed as more beneficial to health, says Donna Brooks, product manager at a prebiotic sweetener company.

Since polydextrose is well-tolerated (at a mean laxative dose of 90g/day), it can be used in various applications such as ice cream, nutrition bars, confections, baked goods and beverages.

Lactitol is a polyol or sugar alcohol with many of the same physiological properties as sucrose, but is only 30%-40% as sweet as sugar. It can be added to replace the bulk of sugar, or it can be used to reduce the amount of sugar if less sweetness is desired, while still maintaining bulk for functionality. Lactitol is typically used in ice cream, chocolate, confections, cakes and cookies.

Inulin, a chicory root extract, is a broad term covering all of the degrees of polymerization (DP) of fructose polymers. Fructo-oligosaccharide (FOS) is a short-chain inulin that extends from 2-10 fructose units. Inulin stimulates the growth of the bifido species bacteria. There is a benefit from inulin at a usage level of as little as 1.25g-2g/serving. However, health benefits are dependent on the DP and the amount of the prebiotic in the product. Combinations of inulin and FOS, as with polydextrose, also can be digested along the entire length of the colon.