Prebiotics are those substances that promote the growth or activity of a limited number of bacterial species in the gut known as probiotics. The ingredients that fall into the prebiotic category have some chemical similarities, but also very different fermentation profiles as well as application advantages.
There are three major categories of prebiotic products. These include short chain fructooligosaccharides (scFOS™), inulin and oligofructose. Currently, these are the most meticulously studied prebiotic ingredients and are the only products on the market that are promoted primarily for the purpose of supporting the growth of beneficial microflora in the gut.
To understand the role of prebiotics in promoting health, one must first learn about the different types, their origins, structures and functions. This is the basic foundation, which will support good choices for formulators and consumers alike.
scFOS, Oligofructose & Inulin
The label “fructooligosaccharides,” or FOS, has been used almost universally when describing the prebiotic category. However, this label is not entirely accurate and a general misunderstanding has occurred, primarily because the differences between the three prebiotic categories are not yet fully understood. scFOS is a specific, defined mixture of glucose-terminated fructose chains with a maximum chain length of 5 units, and 95% pure active prebiotic. It is derived from sugar cane by a natural fermentation process.
Oligofructose, a mixed FOS, is the enzymatic hydrolysis product of inulin. It consists of mixed glucose and fructose-terminated chains, varying in length from 2-7. Inulin is not a fructooligosaccharide because the majority of its chains exceed 10 units.
Among prebiotics, scFOS has a vast array of scientific studies supporting its benefits to health. Originally discovered and produced in Japan, scFOS is a FOSHU—or food for specified health use—ingredient. In Japan and Europe, scFOS is used in hundreds of products in almost every food category. scFOS is mildly sweet, about 30% as sweet at sucrose, provides flavor masking and enhancement advantages and has 1.5 calories per gram.
scFOS can be useful in promoting the growth of probiotic gut microflora, exerting positive effects on digestive health and regularity, improving mineral absorption, enhancing immune function and promoting overall health.
The glucose terminals and short chain length are extremely important to the fermentation profile and ingredient functionality. The chemical structure and relative chain length of a prebiotic will determine how easily probiotic bacteria can use it. As a prebiotic, the 95% active content of scFOS supports the growth of a wide variety of Bifidobacteria and Lactobacilli strains, and does not support the growth of pathogens, in vivo.
Inulin is primarily a long chain, glucose terminated polysaccharide mixture that has a prebiotic effect and is an attractive fat mimetic and bulking agent. Often mistakenly referred to as FOS, inulin is prized for its ability to hold water, replace fat and contribute minimal calories. It is also hailed for its bland flavor profile. It is found in and extracted from a variety of plants and commercially produced from chicory root. Typically composed of approximately 10% oligosaccharides, the long chain polysaccharide structure of inulin gives the substance water-holding abilities, enabling its application in a wide variety of products where a bulking agent can add processing functionality and help consumers meet their daily need for fiber.
Inulin has also been studied by the scientific community for its fermentation profile, ability to stimulate the growth of probiotic gut microflora and potential health benefits. Its predominantly long chain structure ensures long fermentation times in the colon.
Oligofructose is a pleasantly sweet hydrolysis product of native inulin and is found in the market as an oligosaccharide. It consists mostly of linked fructose units, with some glucose-terminated chains. The unbound fructose chains have been shown by science to have prebiotic properties, and impart the ability of oligofructose to brown extensively under heated conditions, unlike inulin.
Oligofructose has a different fermentation profile than either inulin or scFOS, and is known and used as a prebiotic ingredient. Oligofructose is fermented by a wider variety of probiotic bacteria than inulin. It is also available as a mixture with inulin to reduce the amount of non-glucose terminated chains. Oligofructose is about 30-60% as sweet as sugar, and contributes 1.5 kcal/gram to food formulations.
Prebiotic Fiber’s Role in Health Promotion
As a group, prebiotics have been shown to enhance health in a number of ways through the support of probiotic bacteria in the gut. The probiotic bacteria, principally Bifidobacteria and Lactobacilli, exert various beneficial effects on health, both through their direct interactions with the gut, and in their metabolic products. For example, short chain fatty acids (SCFAs) are products of prebiotic fermentation by these gut microflora and are crucial for human health and well being.
The probiotic bacteria and their SCFAs restrict the growth and activity of less beneficial species, including putrefactive and disease-causing bacteria and yeast. The effect of probiotics crowding out bad or less beneficial species is known as competitive exclusion. Competitive exclusion is essentially the good bacteria restricting the bad ones. The SCFAs produced by probiotic strains makes the gut environment less friendly to harmful strains. In addition, there is limited food and space in the colon, so the provision of a food source that is preferred by the good bacteria helps ensure they will have the competitive advantage.
The SCFAs, in particular, are crucial to gut integrity and function, immune system modulation, calcium absorption and cholesterol maintenance. In fact, most of the energy required by the colon is provided directly by SCFAs. If the colon does not have enough SCFAs to provide energy needs, decreased integrity and function may follow. Various “starved bowel” disorders, such as those known collectively as irritable bowel syndrome (IBS), are generally thought to be linked to inadequate SCFA production and a poor balance of gut microflora. The important point about SCFAs is that they are totally provided by probiotic fermentation of prebiotic fibers in the gut. So, the critical nature of adequately nourishing the probiotic bacteria through providing effective prebiotic support is clear.
Trends & Issues
The top trend on the consumer end of functional foods, according to Dr. Elizabeth Sloan, Sloan Trends and Solutions, Escondido, CA, is that people want to manage their health through the foods they eat. This trend is more important to consumers than the fat or nutrient content of foods. People are choosing foods that offer health benefits, and a majority seeks out fortified and enhanced foods. Foods that communicate healthy messages, while delivering taste and convenience with a natural focus will continue to attract consumers.
Another important trend in food products involves the huge youth segment. Rising rates of obesity and its effects on young consumers has been brought to national attention and is driving the need for improved nutritional profiles and products that can deliver a combination of benefits. Youth diets are largely deficient in fiber, calcium, fruits, vegetables and milk. So traditional fortification will remain important, but the use of novel ingredients to improve health, such as prebiotics, will abound. It is also suggested that there will be an increase in fortified and modified products in the snack and confectionery segments.
The belief that consumers have varying individual needs is an important element that is driving the market for functional foods in general, and prebiotics specifically. New products are employing several nutritional approaches to address the needs of singular groups. For example, products are being offered for female-related health issues that may include a combination of herbs, soy, prebiotics and mineral fortification. Many of these are targeted directly toward menopausal women. Bone health is also an ever-growing concern. Formulating for bone health with prebiotics is scientifically sound and presents important synergies with the dairy and supplement sectors.
Synbiotic products—those that combine prebiotics with probiotics for enhanced health benefits—are the major new trend in the dairy sector. Synbiotic yogurts are promising enhanced health benefits, such as improved immune function and increased calcium absorption in addition to overall health benefits. These products are at the forefront in providing consumers with a combination of health benefits in the tasty, convenient forms they enjoy and currently purchase.
Other emerging domestic products incorporating prebiotic fibers include kefir, yogurt and other dairy drinks, sports products, functional waters, nutrition bars, weight loss products, soymilk, green foods, probiotic supplements, mineral supplements, medical foods and pet foods. These products incorporate prebiotic fibers for various health benefits, including enhanced mineral and isoflavone absorption, fiber contribution, gut integrity, immune function and cholesterol control.
Internationally, prebiotic fibers are successfully marketed for the improvement of health through the promotion of a proper balance of gut microflora. Prebiotics are available in almost every product imaginable and are eagerly sought out by consumers looking for healthy options.
The international consumer is well aware of prebiotics, gut integrity, probiotic microflora and their respective roles in health maintenance. Domestically, however, the concept of prebiotics is relatively new to the marketplace, with consumers just becoming aware of their importance. Consumer demand will continue to grow due to familiarity with probiotics and recent product introductions including prebiotics in the yogurt segment. Instructive and fun to read labels on new products will lead the consumer education effort, as food producers using prebiotics are eager to communicate the benefits of these ingredients and explain how they enhance the value of their products.
Internet, print media and joint marketing campaigns have been instituted by the major providers of prebiotic fibers and are critical for informing producers and consumers about the gut’s impact on health and the new ingredients available that build wellness from the inside out. In addition, as healthcare professionals become more aware of prebiotics, they are prompting their patients and clients to seek out appropriate products. This is the result of professional information provided by prebiotic suppliers who currently conduct education campaigns in the healthcare arena for this purpose.
Predictions for the Future
In the future, prebiotic fibers will have a strong position in the nutraceuticals industry. As people increasingly seek simple solutions to wellness issues, they will become even more scrupulous in their choices. The move toward products that provide a combination of benefits with ingredients that have sound, scientific support will explode. For the interests of consumers to be served, the food industry and the scientific community must provide accurate information in order to promote good choices. Communication through all avenues, especially the food label, will be critical for the necessary transfer of knowledge to take place.
Health conscious consumers have been the first to realize the many benefits of prebiotics. A growing population is seeking out and using products that contain prebiotics. These are the consumers that will buy a product for the health benefits and are the easiest target for functional foods.
The larger segment, the group that does not buy primarily for health reasons, will go through a shift based on a new environment that is being created in the market. The FDA’s recognition of the need for increased label communications is resulting in new opportunities for food producers to broadcast the health benefits of their products in a responsible, but highly accessible way. This, combined with the most recent reports of soaring obesity and degenerative disease rates and the threat of litigation against the food industry, has created an environment of formulating for health previously unknown.
Prebiotic enhancement is a valuable tool for food companies looking for a competitive edge in this changing playing field. The best players will ensure their products are fortified with a prebiotic that is effective, while also adding to the sensorial enjoyment of everyday foods.
About the author: Linda Douglas, PhD, RD, is manager of technical affairs at GTC Nutrition, Golden, CO. She can be reached at 303-216-2489; Fax: 303-216-2477; E-mail: [email protected]; Website: www.gtcnutrition.com.