Proof that dietary fiber boosts digestive health can be found in many current research studies. Rhonda Witwer, senior business development manager, nutrition, for Corn Products International/National Starch Food Innovation, Bridgewater, NJ, reports on several recent studies and their exciting results in Part 1 of an interview exclusive to Baking & Snack.

Baking & Snack: How does dietary fiber foster better digestive health in humans? Can you share recent research that supports this capability or describes mechanism for this activity?

Dan Gallaher at the University of Minnesota has published a 2-by-2 grid or matrix describing different mechanisms of dietary fiber (“Present Knowledge of Nutrition,” published by ILSI Press in 2006). It presents a simple way to describe mechanisms of all of the dietary fibers. He identified that there are three major mechanisms: bulking, fermentation and viscosity. He simplified it down to the following:

The bulking fibers are not fermented and occur on the bottom row. They hold a lot of water and promote regularity by helping to move the intestinal contents through the intestinal track. However, their benefits are limited because they are not fermented or are minimally fermented. For instance, wheat bran (cellulose) and psyllium produces the largest regularity effects because they hold the most water, but a recent clinical study found that people eating cereal high in psyllium required six months of daily consumption before the biomarkers for fermentation in their blood significantly changed (Wolever et al., American Journal of Clinical Nutrition 2002; 75:1023-30.) Benefits that are driven by fermentation will not be seen in people eating these types of dietary fibers.

Viscosity is the second major mechanism of dietary fiber. Highly viscous fibers slow the absorption of cholesterol and glucose because they thicken the intestinal contents and reduce the migration of these nutrients to the mucosal barrier, where they can be absorbed. Beta-glucan is well known for its cholesterol lowering effects, but low molecular weight beta-glucan which is lower in viscosity, does not deliver the benefit. (Wolever et al., American Journal of Clinical Nutrition, 2010 Oct; 92[4]:723-32.) However, viscous fibers present formulation difficulties and can interfere with taste, which limits their usage.

The third major mechanism of dietary fiber is fermentation. Research is overwhelmingly demonstrating that fermentation of indigestible carbohydrates triggers significant health benefits, including promoting the health and functioning of the digestive tract, supporting immune health and mineral absorption. Our ingredients deliver strong digestive health benefits because they are preferentially fermented by beneficial bacteria, producing short-chain fatty acids (SCFAs), which cause a biochemical cascade of positive effects. Different types of dietary fiber produce different ratios and amounts of SCFAs, which produce different physiological effects. There is a tremendous amount of research investigating the health effects of different ingredients with a wide variety of results. This area of research is quite robust right now as traditionally, the digestive system has been viewed as simply an extractor of nutrients, but the health effects of fermentation are demonstrating that the large intestine actively contributes to health (or the lack of health) via fermentation.

NutraFlora short-chain fructooligosaccharides

More than 200 studies have been published over the past 20 years showing the health effects of short-chain fructooligosaccharides (scFOS) NutraFlora scFOS is a natural prebiotic soluble fiber ingredient offered by Corn Products/National Starch with approximately 12 clinical trials published demonstrating its prebiotic effects. It is considered more prebiotic than inulin and oligofructose and preferentially fermented, becoming a food source for Bifidobacteria and Lactobacillus species within the large intestine. Increasing Bifidobacteria is dependent on chain length of the food source for them; NutraFlora scFOS has a short chain length and therefore preferentially fermented. Keeping these friendly bacteria healthy and happy helps them to defend the lower intestinal tract from pathogens — supporting immune health through pathogen inhibition (Hidaka et al 1986) and helps foster proper digestive function.

When NutraFlora scFOS supports probiotic bacteria in the intestine, these beneficial cultures produce SCFAs. These SCFAs are crucial for health. They increase calcium carriers in the intestine and keep calcium and magnesium in optimal solution for enhanced absorption (Ohta et al 1999 and Uenishi et al 2002). This is another important aspect of NutraFlora scFOS in that even if one was to eat a diet rich in calcium, it does not guarantee that their body will be able to perform adequate calcium absorption. The addition of NutraFlora scFOS provides assurance backed by published clinical studies that one is providing enough support for Calcium absorption via NutraFlora scFOS. Consumers can make sure that their body’s “bank” of calcium is well-stocked & deposited with the inclusion of NutraFlora scFOS.

Lastly, NutraFlora scFOS can have a positive impact on digestive discomfort. A 2008 study involving 105 individuals with functional bowel disorders (abdominal bloating, rumbling, occasional constipation and/or diarrhea, abdominal pains and flatulence) found that regular consumption of 5 g of NutraFlora scFOS significantly improved performance in daily activities and increased digestive comfort in a working population with mild digestive issues (not requiring medical treatment). (Paineau D, et al., "The effects of regular consumption of short-chain fructooligosaccharides on digestive comfort of subjects with minor functional bowel disorders," British Journal of Nutrition (2008) 99:311-318).

Purimune galactooligosaccharides

Galactooligosaccharide (GOS) is the third largest solid component of breast milk (after lactose and fat). It reaches the large intestine and is selectively fermented by Lactobacillus and Bifidobacteria, which lowers the intestinal pH. Purimune GOS, a product of Corn Products and National Starch, also prevents the adhesion of pathogenic bacteria to the colonic cell wall. As a result, the pathogenic bacteria wash out and are reduced in number. Two studies have shown that GOS is effective in improving symptoms in individuals with irritable bowel syndrome as well as ulcerative colitis (described below).

A March 2009 study found that GOS improved the symptoms in individuals with irritable bowel syndrome (IBS). The three classic symptoms were measured: abdominal pain or discomfort, bloating or distension, and bowel movement difficulty. Individuals consuming 3.5 g GOS per day significantly increased Bifidobacteria and reduced Clostridium perfringens and Bacteroides species. They also experienced significant improvements in stool consistency, flatulence and bloating. The authors concluded: “The galactooligosaccharide acted as a prebiotic in specifically stimulating gut bifidobacteria in IBS patients and is effective in alleviating symptoms. These findings suggest that the prebiotic has potential as a therapeutic agent in IBS.” (Silk DBA, Davis A, Vulevic J, Tzortzis G, Gibson GR. "Clinical trial: the effects of a trans-galactooligosaccharide prebiotic on faecal microbiota and symptoms in irritable bowel syndrome." Alimentary Pharmacology & Therapeutics. March 2009, 29[5]:508-518. doi: 10.1111/j.1365-2036.2008.03911.x)

Another recent study found that GOS combined with a probiotic improved the clinical conditions of patients with mild to moderate ulcerative colitis (UC). A total of 41 patients with mild to moderate ulcerative colitis participated in this study. Half received symbiotic ingredients while half received placebos. At the end of one year, colonoscopies revealed that the UC patients receiving GOS and probiotics were significantly improved: the fecal counts of Bacteriodaceae and fecal pH were reduced as were other biomarkers of ulcerative colitis. (Hideki Ishikawa, Satoshi Matsumoto, Yuji Ohashi, Akemi Imaoka, Hiromi Setoyama, Yoshinori Umesaki, Ryuichiro Tanaka, Toru Otani. Beneficial Effects of Probiotic Bifidobacterium and Galactooligosaccharide in Patients with Ulcerative Colitis: A Randomized Controlled Study, Digestion April 2011; 84:128-133 (doi: 10.1159/000322977).

Finally, a newly published 2011 study found that healthy students with a healthy weight consuming short-chain GOS (Puimune brand) during times of stress (undergoing finals) experienced 40% fewer colds and flu compared to students consuming a placebo They also had fewer gastrointestinal distress symptoms (diarrhea, constipation, abdominal pain and indigestion). (Hughes C, Davoodi-Semiromi Y, Colee JC, Culpepper T, Dahl WJ, Mai V, Christman MCC, Langkamp-Henken B. "Galactooligosaccharide supplementation reduces stress-induced gastrointestinal dysfunction and days of cold or flu: a randomized, double-blind, controlled trial in healthy university students." American Journal of Clinical Nutrition June 2011; 93[6]: 1305-11. doi: 10.3945/ajcn.111.014126). This study confirms that immune health is intimately related to gastrointestinal health and that dietary consumption of Purimune GOS supports digestive health and provides immune enhancing benefits.

Hi-maize resistant starch

Resistant starch is simply starch that reaches the large intestine. Intact whole grains, beans, under-ripe bananas and lentils provide large quantities of resistant starch in our diet. Hi-maize resistant starch [a product of Corn Products and National Starch] is starch from high-amylose corn, which also naturally resists digestion. It has a strong advantage in food processing because it is a white powder with a bland taste which easily replaces flour for an invisible fiber boost. Over the past 20 years, more than 150 studies have demonstrated digestive health benefits of Hi-maize resistant starch. It is fermented by the resident bacteria in the large intestine and produces more butyrate than any other fiber tested. Butyrate helps keep colonic mucosal cells healthy and functioning properly.

Editor’s note: This discussion continues in "Improving digestive health, part 5."