The Buzz on Beta-Glucans

The Buzz on Beta-Glucans

By Sharon Palmer, R.D.
Contributing Editor

Arebeta-glucans poised to be the next it ingredient? A growing body ofscience indicates that beta-glucans promote health in a number of importantways. Some scientists even believe that beta-glucans show promise in reducing therisk of metabolic syndrome, a cluster of conditionsincluding obesity, highblood sugar, dyslipidemia and high blood pressurethat often occur togetherand can lead to heart disease. Since about 25% of Americans suffer frommetabolic syndrome (a number thats expected to double over the next 15years), and coronary heart disease is the leading cause of death and permanentdisability in the United States, beta-glucan is big news. Its going totake some long-term studies to pull some of this information out, but I seebarley and oats incorporated into an overall healthy diet that is high in beta-glucans as having a positive impact on metabolic syndrome, saysChristine Fastnaught, Ph.D., barley food consultant, Fargo, ND.

In December 2005, FDA amended its regulation authorizing a health claim onthe relationship between oat beta-glucan soluble fiber and reduced coronaryheart disease by adding whole grain barley and certain drymilled barley grainproducts as additional eligible sources of that same fiber. The health claim isbased on consuming 3 grams of beta-glucan soluble fiber daily; that can bedivided into sub-doses as small as 0.75 grams each.

Up close 

Beta-glucans occur in the bran of grasses such as barley,oats, rye and wheat, in amounts of about 7%, 5%, 2% and less than 1%,respectively. Yeast and mushrooms also contain this fiber. Glucans are polysaccharides madeup of chains of glucose molecules. The term beta refers to the stericposition of the glucose hydroxyl group involved in the chain formation. Theterms beta-1,3- and beta-1,6-glucans are often used, with the numbers referringto the positions on the glucose molecules that link them together. Beta-glucansare considered to be water-soluble fiber in the diet and are non-digestible, dueto the absence in the human body of an enzyme capable of hydrolyzing the beta-glucosidic linkage.

Disease busters 

Dietary oats, oat bran, purified beta-glucans fromyeast, and barley beta-glucans have been studied for their hypocholesterolemiceffects. Proposed mechanisms that may account for their cholesterol-loweringproperties include: reducing the intestinal absorption of cholesterol and bileacids by binding to glucans; shifting the liver from cholesterol syntheses tobile acid production; and fermentation by intestinal bacteria to short-chainfatty acids, which are absorbed and inhibit hepatic cholesterol syntheses.

Various studies have also shown that oat beta-glucans blunt the glycemic andinsulin response. Oat extracts rich in beta-glucans were found to improveglucose tolerance and lower insulin output in moderately hypercholesterolemic men and womenconsuming a normal diet. In another study, oat beta-glucan reduced the glycemicindex (GI) of a 50-gram carbohydrate portion by 4 units for each gram of beta-glucan.Modulating blood glucose concentrations following consumption of acarbohydrate-containing meal is another potential benefit area which holdspromise for beta-glucans, says Mark Andon, Ph.D., director of nutrition atQuaker/Tropicana/Gatorade, Chicago.

In addition, beta-glucans have been linked to enhanced macrophage, Blymphocyte and suppressor T cell action, and increased non-specific-hostresistance to a variety of bacterial, viral, fungal and parasitic infections.Beta-glucans have also been linked to reducing blood pressure and inducingsatiety that can lead to weight loss.

Three grams 

Will the day come when beta-glucans are splashed on foodlabels as prominently as antioxidants? While Quaker extols the heart-healthybenefits of oats on product labels, they have steered clear of the word betaglucan,instead choosing the term soluble fiber as easier to mentally digest.Lisa Carlson, M.S., R.D., director of professional marketing at Quaker, believesthat consumers understand the message that soluble fiber helps lowercholesterol, but most dont understand the benefits of beta-glucans.

Much of the evidence on beta-glucan promotes a food-based approach ofincreasing whole-grain cereal consumption for heart-disease prevention. Beta-glucan supplements will not deliver the same benefits as consumingbeta-glucan-containing whole foods, such as oatmeal, says Andon. Old-fashioned oats contain about 2 grams of soluble fiber in 12 cup(uncooked), and steel-cut oatmeal contains about 2 grams of soluble fiber in 14 cup (uncooked).

Upping the beta-glucan ante 

Manufacturers can rely on ingredientssuch as barley flour or oat bran to pump beta-glucan levels in foods. A numberof new products are poised to push beta-glucans even further. Cargill, Minneapolis, announced its new barley product,Barliv, with a 70%concentration of beta-glucans. George E. Inglett, an Agricultural Research Service chemist at the NationalCenter for Agricultural Utilization Research in Peoria, IL, recently developed abarley and oat bran ingredient called Nutrim. ARS scientists at North DakotaAgricultural Experiment Station, North Dakota State University, published theirjoint registration of HiFi, a new spring oat cultivar with 50% more beta-glucanthan regular oats. Nutritech International, Kristianstad, Sweden, launched Aktiv barley powder.OatVantage, made by Nurture, Inc., Missoula, MT, is an oat-bran concentratecontaining 54% beta-glucans. Cevena, Edmonton, Alberta, created Viscofiber, a barley concentrate with 60%beta-glucans, or oat concentrate with 50% beta-glucans. Takeda-Kirin Foods Corporation, Tokyo, developedPureglucan® curdlan, whichhas a minimum content of 90% beta-glucans derived from microbial fermentation ofglucose.

While research has focused primarily on the health benefits of beta-glucansfrom whole foods, some scientists are now exploring the effects of betaglucan-enriched products. Researchers from Lund University, Sweden, isolated beta-glucan from oats andincorporated it into three foods that do not normally contain beta-glucans:fruit beverages, readymeals and feta cheese. Results indicated that the isolatecould be used in low amounts in such foods.

In a study performed at Maastricht University, Netherlands, researchersconcluded that beta-glucan lowers serum concentrations of total and LDLcholesterol when incorporated into a fruit drink, without affecting plasmaconcentration of lipid-soluble antioxidants.

Beta-glucan appears to have all the earmarks of a winning functional foodingredient, as long as consumers are ready to recognize it by name.

Sharon Palmer is a registered dietitian and freelance writer living insouthern California with 16 years of foodservice and clinical nutritionexperience.