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By Mark Anthony, Ph.D. | 09/01/2006
Denis Burkitt, M.D., a legend for identifying and treating cancer of the lymphatic system (Burkitt’s Lymphoma), was also a pioneer in fiber research. His “fiber hypothesis,” developed with fellow researcher Hugh Trowell in the late 1960s, stemmed from their research in Uganda. They observed that Ugandan patients living on a native diet rich in plant food and high in fiber rarely developed colon cancer, heart disease or diverticulitis.
This was in sharp contrast to the British residents of Uganda living on a low fiber diet rich in meat and refined white bread. Burkitt’s book “Don’t Forget the Fiber in Your Diet” marked the official beginning of the fiber revolution. High fiber diets relieve constipation and help lower cholesterol.
Some fibers decrease transit time, reducing the exposure of potential carcinogens to the gut wall. From the 1970s on, soluble and insoluble fibers were hot ingredients and getting them into the diet drove the recommendations to increase the consumption of fiber-containing foods.
The gastrointestinal tract is also one of the body’s first lines of defense against disease. The gut is assaulted daily by invading pathogens, toxins and other disease-causing agents and carcinogens.
“Numerous studies have investigated the beneficial effect of probiotics in preventing and treating digestive illnesses through the modulation of bacteria present in the gastrointestinal tract,” notes Joe O’Neill, vice president for sales and marketing for Orafti Active Food Ingredients (www.orafti.com), Malvern, Pa. “Additional studies are demonstrating the immune-system modulating effects of the prebiotics inulin and oligofructose.”
We share our most personal space with a massive population of bacteria. An estimated 500 to 1000 different species have taken up residence in each one of us. In addition to the study of gut microbes that can harm us — Escherichia coli, Salmonella, Helicobacter pylori and Clostridium difficile — we’re now focusing attention on the friendly bacteria, ones that allow us to extract maximum benefit from our diet by breaking down substances that otherwise would be indigestible.
Inulin is a fashionable functional fiber suitable for bars, baked goods, yogurt products or smoothies.
Today, research on diet and intestinal health has entered a new phase where attention is focused on the microbial populations that reside in the gut.
The influence of healthy gut bacteria extends to immune enhancement, tissue repair and even the health of the neurons that control gut motility. Healthy bacteria convert plant-lignan precursors to the animal lignans enterolactone and enterodiol. Like isoflavones, these lignans may protect against hormone-sensitive cancers such as those of the breast and prostate. We pay for this service by providing a safe, nutrient-rich environment in which beneficial microbes can multiply and pursue happiness.
Probiotics (beneficial gut microbes) and prebiotics (the food the microbes ferment for energy) are now big buzzwords in health ingredients. It has becomes increasingly apparent health is inseparable from friendly gut bacteria.
Chr. Hansen (www.chr-hansen.com), Milwaukee, is one of the leading providers of healthy probiotics. The company supplies most of the major manufacturers of yogurt and yogurt products with a full range of good bugs. Among the company’s proprietary, clinically documented strains are BB-12 (Bifidobacterium), LA-5 (Lactobacillus acidophilus) and L.casei 431 (Lactobacillus casei). Hansen also provides other probiotic strains of lactobacillus, bifidobacterium, and streptococcus.
Like all critters, healthy gut microbes have to eat. And their table manners can provide us with some pretty valuable leftovers, depending on how they’re fed. These insatiable creatures ferment indigestible carbohydrates –fibers and resistant starches – into the short chain fatty acids acetate, butyrate, and propionate.
Acetate and propionate provide energy for the muscles, including the heart. Propionate is also helpful in controlling inflammation of mucosal cells. Butyrate feeds cells of the colon wall, but more importantly the chemical may modify lifespan, proliferation and differentiation of cancer cells, reducing the risk of colon cancer.
The fermentation of carbohydrates into short-chain fatty acids acidifies the colon environment and may stimulate the absorption of minerals such as calcium. Calcium, well-known for bone health, has experienced a wealth of new research into possible cancer preventive characteristics.
Care in feeding microbes is important. In the absence carbohydrates, microbes such as clostridia ferment protein for energy, leaving behind harmful nitrogenous metabolites such as biologic amines, indoles, and ammonia, all of which could increase the risk of cancer.
The term prebiotics was introduced in a 1995 as “non-digestible food ingredients that beneficially affect the host by selectively stimulating the growth and/or activity of one or a limited number of bacteria in the colon.” Prebiotics have some inherent advantages for maintaining a healthy gut. By feeding beneficial bacteria in the gut, you avoid the problems of trying to passively keep probiotics – good microbes – alive. Prebiotics can be added to a much broader range of foods than probiotics. Adding prebiotics imitates what the body already does when it produces endogenous prebiotics.
Not all dietary fibers are prebiotics. Some fibers may be fermented by a large variety or gut microbes or, depending on their properties, may avoid fermentation completely. Prebiotics are fermented by a select group of colonic microbes. Presently, substrates for prebiotics include polymers of fructose, such as inulin, or carbohydrates such as polydextrose, galacto-oligosaccharides, xylo-oligosaccharides and others.
Mixtures of different prebiotics may be used to support a beneficial balance of microbes, rather than a specific genus. For example, fermentation occurs at different rates, depending on the characteristics of the prebiotic. Fast-fermenting prebiotics – which may not reach the distal colon – may be complemented with slower fermenting polymers to deliver beneficial products throughout the colon.
Sensus America (www.sensus.us) produces and markets both Frutafit and Frutalose. These inulin and fructo-oligosaccharide products, extracted from chicory, a major source of the prebiotic ingredients used in food and beverage processing. Sensus recommends, “A daily intake of 5 grams of inulin or fructo-oligosaccharides significantly increases positive gut bacteria (bifidobacteria and lactobacilli).”
“The most important things to consider when developing new pre- and probiotic combinations is determining whether or not the balance between the two types will remain stable,” says Donna Brooks, product manager for Danisco Sweeteners (www.danisco.com/sweeteners), Elmsford, N.Y. “Exposure to acid conditions, within either the food system or the stomach is important, as well as stability under systems with higher water activity.” Danisco makes Litesse polydextrose, a prebiotic fiber that highly stable over a broad pH range and variety of processing and storage conditions.
“The future for pre- and probiotic research will focus on the combination of prebiotics and probiotics to determine potential synbiotic effects,” adds Brooks. “Danisco has already begun to look at Litesse in combination with our probiotics in several application areas. There’s a growing opportunity for the use of both, as this concept is in its infancy in the U.S. market.”
Brooks believes additional interest by consumers in gut health will drive new innovation for pre and probiotics and ultimately lead to new product development both inside and outside of the dairy segment.
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