Digestive Health

Digestive health is now on the radar of the federal government. In September, National Institutes of Health (NIH; Bethesda, MD) director Elias Zerhouni, MD, announced that the newly formed National Commission on Digestive Diseases is ready to assess state-of-the art science to address the needs of gastroenterologists and their patients.

“The creation of the National Commission on Digestive Diseases is a landmark event in the advancement of the science and practice of gastroenterology,” says David Peura, MD, president of the American Gastroenterological Association (Bethesda, MD). “Our goal in proposing the commission was to obtain the funds and focus needed to increase the rate of discovery and to translate advances into clinical practice.”

The commission, charged with the task of identifying areas of research opportunity, should galvanize scientific efforts to learn more about digestive health. In addition to identifying new pharmaceutical treatments, researchers have also been studying whether other approaches, such as nutritional intervention and supplementation, may be beneficial for people with digestive health concerns.

BENEFICIAL BACTERIA

One of the most promising areas of nutrition research for digestive health involves gut microflora. Scientists are learning more about how beneficial probiotic strains of bacteria and prebiotic fibers that enhance the growth of those bacteria can improve digestive health. Researchers are also investigating how genetics may play a role in the way probiotics function in the digestive tract.

For example, researchers from Washington University (St. Louis) reported in the March 25, 2005, issue of the journal Science that a common bacteria in the human gut activates more than a quarter of its genes when its host switches from eating simple sugars to complex carbohydrates. The bacteria, Bacteriodes thetaiotamicron (B. theta), normally helps the body break down indigestible carbohydrates.

The Washington University researchers inoculated special germ-free mice that had no intestinal bacteria with B. theta and fed them diets that were either high in simple sugars or complex carbohydrates. After 10 days, 1237 of the bacteria’s 4779 genes were highly active in the complex carbohydrate group, compared with the genes in the simple sugar group. Most of the activated genes were involved in the digestive process, according to the researchers. “In mice fed complex carbohydrates, we found that the microbes attached to small food particles in the intestine,” says Jeffrey Gordon, MD, director of Washington University’s Center for Genome Sciences. “These carbohydrate-rich particles are the bacteria’s dining room table. By generating a series of carbohydrate-binding proteins on its outer surface, B. theta is able to hold onto a seat at the table.” Gordon added that enzymes produced by the bacteria act like utensils that break the carbohydrates into “bite-sized” pieces.

Meanwhile, researchers from the University of Alberta (Edmonton, AB, Canada) have found that a mixture of several different bacteria dubbed VSL#3 may offer some relief to people with ulcerative colitis. In the July 2005 issue of the American Journal of Gastroenterology, the Canadian researchers reported that 86% of those treated with VSL#3 felt relief of mild to moderate symptoms after six weeks. However, the open-label study was preliminary and only involved 30 subjects. According to Richard Fedorak, MD, a professor of gastroenterology at the University of Alberta, VSL#3 one day may be of use to people who don’t respond to conventional therapy.

FUNCTIONAL FIBERS

New studies on prebiotic fibers are also proceeding apace. Research conducted in Europe recently led AFSSA, France’s food safety agency, to approve a health claim for food products containing native chicory inulin, according to Steve Snyder, vice president of sales and marketing at Cargill Health & Food Technologies (Minneapolis), which offers an inulin ingredient called Oliggo-Fiber.

Snyder also notes that a randomized, double-blind, placebo-controlled trial submitted to international authorities by Cargill’s inulin supplier, the Cosucra Group (Warcoing, The Netherlands), demonstrated that inulin supports digestive health. “Inulin is a very versatile ingredient with many health-promoting benefits,” says Snyder, adding that data from the European studies suggest that 2.5 g of inulin twice a day can promote the growth of beneficial bacteria.

Pam Stauffer, marketing programs manager at Cargill, adds that inulin provides several functional benefits in addition to its health benefits. For instance, Oliggo-Fiber can mimic fat, replace carbohydrates, modulate flavors, and extend shelf life. “Oliggo-Fiber inulin provides a unique opportunity to increase soluble dietary fiber content in a range of great-tasting, mainstream foods and beverages,” Stauffer says.

Another prebiotic fiber, Orafti’s (Malvern, PA) Raftilose Synergy 1, an oligofructose-enriched inulin, was the subject of a recent study on calcium absorption and bone mineralization in young adolescents by researchers at Baylor College of Medicine (Houston) and the Texas Children’s Hospital (Houston).

In the study, 100 volunteers received either 8 g of Raftilose Synergy 1 with breakfast each day or a placebo for a year. Before the study, the researchers measured bone mineral content and density using X-ray body scans. The researchers also repeated the same tests after two months and at the end of the study. According to the researchers, the study data confirmed the results of an earlier study that found that Raftilose Synergy 1 increased calcium absorption by 20%.

“This study is an exciting step forward, advancing the science and reconfirming the dramatic effect of Raftilose Synergy 1 on bone health,” says Kathy Niness, vice president of marketing and sales at Orafti. “It adds to the strong body of scientific evidence already proving that Raftilose Synergy 1 increases calcium absorption and confirms that it also increases bone density over the long term. This is the first study of its kind proving this effect for any prebiotic ingredient, and we are pleased it was conducted with Raftilose Synergy 1 at the prestigious USDA Center for Human Nutrition at Baylor University in Texas.”

Although most of the new research has been positive, at least one recent study on probiotics and prebiotics has sparked controversy. In April, a team of Dutch scientists suggested in an article in the Journal of Nutrition that fructooligosaccharides (FOS) may raise the risk of salmonella infection in rats by increasing intestinal permeability.

But according to Linda Douglas, PhD, scientific affairs manager at GTC Nutrition, which supplies NutraFlora short-chain FOS derived from sugar, not all prebiotics are the same.

“This recent study was conducted with chicory oligofructose,” Douglas says. “To attribute the results of this study to prebiotic ingredients in general is inappropriate, given the significant differences among prebiotic products. A body of scientific evidence demonstrates that NutraFlora helps to prevent salmonella infections.”

Jim Low, general manager of GTC Nutrition, adds that the company currently holds two U.S. patents for the use of short-chain FOS to inhibit salmonella infections. “We are committed to communicating the scientifically and clinically proven benefits of NutraFlora,” Low says.

FUNGAL FACTS

Mushrooms, which are well known for their contribution to international cuisine, are also a little-known source of dietary fiber. Several varieties of mushrooms are rich in nutrients, particularly the fibers chitin and beta glucan, according to researchers from the University of Illinois at Urbana-Champaign. The new data, which were published in the February 2005 issue of the Journal of Agricultural and Food Chemistry, provide complete carbohydrate profiles, including digestible carbohydrates, starches, and fermentable fibers.

The researchers analyzed white button, crimini, and portabella mushrooms, which are different forms of Agaricus bisporus; as well as maitake (Grifola frondosa), shiitake (Lentinus edodes), and enoki (Flammulina velutipes) mushrooms. High-performance liquid chromatography was used to determine the chitin levels in the mushrooms, while a spectrophotometer was used to analyze beta glucan levels and quantify the amount of total dietary fibers.

“The maitakes and shiitakes tended to be very similar in their nutrient concentrations, and quite a bit different than the others,” says lead author Cheryl Dikeman. “Portabellas were off on their own in terms of their contents of oligosaccharides, beta glucans, and chitin.”

Chitin concentrations were 8% in raw, mature portabellas and 6% in raw, immature ones. Chitin content dropped after cooking to 2.7% in both types. Meanwhile, beta glucan was highest in raw, mature portabella mushrooms, which had levels of 0.2%. The same mushrooms also had high levels of oligosaccharides, averaging about 5272 µg/g. Cooking the mushrooms appeared to raise total dietary fiber content.

The Mushroom Council (Dublin, CA) provided funding and samples for the research, which will be incorporated into the U.S. Department of Agriculture’s (USDA; Washington, DC) National Nutrient Database.

OTHER RESEARCH

Prebiotics and probiotics may be taking the lion’s share of research headlines, but scientists are also studying a variety of other ingredients that may contribute to digestive health.

One unusual ingredient that might turn out to be beneficial is grapeseed extract (GSE). Grapefruit is acidic, but it also contains antioxidant and antibacterial compounds that may actually soothe, rather than irritate, the gastrointestinal tract. According to research presented at Digestive Disease Week, a conference held May 14–19 in Chicago by several medical societies, GSE may accelerate ulcer healing through a mechanism that involves COX-1 and COX-2 activity. In a study conducted by researchers from Jagiellonian University (Krakow, Poland), researchers induced gastric ulcers in rats and then administered graded doses of GSE ranging from 2 to 20 mg/kg. Rats that received 10 mg/kg experienced a 50% reduction in gastric acid secretion, along with a progressive reduction in the area of gastric ulcers as the study progressed.

“Because grapefruit is acidic in nature, people with ulcers might assume that they should not include the fruit in their diet,” says Thomas Brzozowski, MD, PhD, lead author of the study. “However, this research suggests the exact opposite. The antioxidant properties found in grapefruit and the ability of this fruit extract to limit oxidative stress in the ulcerative gastric mucosa have therapeutic properties that, when combined with additional therapies, can be especially beneficial for healing of gastric ulcers.”

Another ingredient under discussion is vitamin B6. Researchers from the Karolinska Institutet (Stockholm) reported in the June 2005 issue of the journal Gastroenterology that women with high dietary intake of vitamin B6 had a decreased risk of colorectal cancer, and women who consumed moderate to high amounts of alcohol along with the vitamin B6 had more than a 70% reduced risk of developing colorectal cancer. To write the study, the researchers used data from the Swedish Mammography Cohort, which contains data from nearly 67,000 women.

“Consuming a diet high in vitamin B6 may reduce the risk of colorectal cancer in women, more specifically, those who consume alcohol,” says Susanna Larsson, MSc, the study’s lead author. “Inadequate vitamin B6 status may lead to the development of cancerous polyps in the colon, so it is important for women to maintain a normal to high intake of vitamin B6.” However, the researchers added that further confirmation in large prospective cohort or intervention studies is needed. Moreover, the vitamin B6 intake measured in the study was from food sources rather than supplements.

NEW PRODUCTS

Although the latest research on natural digestive health ingredients is still unfolding, food and supplement manufacturers have been using existing research to improve products that are already on the market. For instance, Nutraceutix (Redmond, WA) recently teamed with General Nutrition Centers Inc. (Pittsburgh) to reformulate GNC’s Natural Brand line of probiotics. Nutraceutix helped by supplying GNC with its LiveBac manufacturing process, which extends the shelf life of probiotics by minimizing the effects of air, heat, and moisture. GNC’s Natural Brand products also make use of Nutraceutix’s patent-pending Bio-Tract gastric-acid bypass technology, which delivers ingredients to the gastrointestinal tract over an extended time frame.

“GNC recognized the barriers to effective probiotic supplementation early in the game,” says Randy Schoenfeldt, vice president of business development at Nutraceutix. “GNC knows what makes a good probiotic supplement and, after learning of our capabilities, challenged us to help them develop a superior line of probiotic products for their savvy customers.”

Chr. Hansen Inc. (Milwaukee) and Tetra Pak (Vernon Hills, IL) have also been working together to develop innovative probiotic products. In September, Chr. Hansen announced that its new Direct Liquid Inoculation system enables manufacturers to add beneficial bacteria to milk or juice after heat treatment in a closed and sanitary system. Under normal processing conditions, heat treatment of beverages kills the fragile bacteria.

“Researchers and food companies all over the world have long been looking for a way to overcome this obstacle, but so far without much luck,” says Hans Christian Bejder, marketing manager for probiotics at Chr. Hansen. “I am very pleased that we became the first to present a suggestion for a viable solution. The door is now open to a whole new range of possibilities for food producers around the world.”

Another probiotic supplier, Nebraska Cultures (Walnut Creek, CA), is attempting to reach consumers through a different venue: publishing. In January, the company noted that Cultivate Health from Within: Dr. Shahani’s Guide to Probiotics, a book written by Nebraska Cultures founder Khem Shahani, PhD, had received favorable reviews from best-selling authors Frederic Vagnini, MD, and Christiane Northrup, MD.

Innovation is also coming from a new source: the U.S. government. Scientists from USDA’s Agricultural Research Service (ARS) are behind the creation of a new fiber ingredient called C-Trim, which contains 20–50% beta-glucan sourced from whole oats and barley. C-Trim has 5–10 times the soluble fiber of regular milled oats, flour, and oatmeal, but is low in calories. Attendees at a recent meeting of the American Chemical Society (Washington, DC) sampled cookies, trail mix, chocolate, smoothies, and peanut butter made with the novel ingredient. ARS scientists avoided using chemical solvents by developing a new method that relies on mechanical shearing, centrifugation, steam-jet cooking, and drum drying to extract the beta-glucan. According to ARS, FutureCeuticals (Momence, IL) has licensed the extraction method.

Last but not least, demand for new fiber products is also causing suppliers to ramp up their production efforts. In August, Orafti announced that Chilean president Ricardo Lagos had visited the construction site of the company’s new processing plant located in San Pedro, 400 km south of the Chilean capital, Santiago. The factory, which cost about $202 million, will produce the company’s Raftilose oligofructose and Raftiline inulin. Orafti expects construction of the plant to be completed in February 2006.