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Beta Glucan

What are beta-glucans?

Beta-glucans are indigestible carbohydrates, polysaccharides composed of glucose. They are dietary fiber. Two types of beta-glucans are described below: beta 1,3/1,4 D-glucan (soluble fiber), and beta 1,3/1,6 D-glucan (insoluble fiber).

Food Sources of Soluble Beta 1,3/1,4 D-Glucan

Beta 1,3/1,4 D-glucans, found mainly in oats and barley, are soluble in water and fermentable: beneficial intestinal bacteria can break them (ferment) to short-chain fatty acids (SCFAs), which can be absorbed [1]. The digits 1,3 and 4 identify positions of carbon atoms in glucose molecules involved in bonds.

Foods high in beta 1,3/1,4 D-glucan [1]:

  • Whole oat foods: oat bran, rolled oats, whole oat flour. 1/2 cup or 120 mL of cooked oat bran, or 1 cup of cooked oatmeal contains 1.5 g of beta glucan (Soluble fiber, Chart 3)
  • Barley foods: whole grain barley, dry milled barley or pearl barley. 1/4 cup or 60 mL of dry pearl barley, which yields 1 cup or 237 mL of cooked barley contains about 2.5 g of beta-glucan [20].

Possible Beta 1,3/1,4 D-Glucan Benefits

Cholesterol Levels and Heart Disease

  • In various studies, consuming 3-6 g of oat-derived beta-glucan extract per day lowered total blood cholesterol and LDL cholesterol in individuals with normal or increased cholesterol levels for 5-9% for as long as beta-glucan was consumed, but did not lower triglycerides or raise HDL cholesterol [1,5,6,7,8]. The US Food and Drug Administration (FDA) allows the claim “may reduce the risk of heart disease” on the labels of certain oat and barley food products [9].
  • Oat bran and, at a lesser extent, oatmeal, can reduce the total and LDL cholesterol blood levels. In one study, consuming oat bran in a dose 2 oz  or 57 g dry, which is 1.5 cup or 355 mL cooked per day for six weeks lowered LDL cholesterol in individuals with increased cholesterol by 16% in average [10].
  • In another study, barley extract, pearl barley, barley bran flour or barley beverages, consumed in doses that provided 3-10 g beta-glucan/day for 4-12 weeks lowered the total and LDL cholesterol and triglycerides, but did not alter HDL cholesterol [14].

The cholesterol-lowering effect of beta-glucan may increase with its viscosity, solubility, dose and molecular weight (oat>barley glucan) and may gradually decrease after weeks/months of taking [1,10,18]. Beta-glucan added to juice may have greater effect than beta-glucan in bread or cookies [1,11]. Additionally, different people may respond differently to beta-glucan [1].

Supplements Containing Insoluble Yeast Beta 1,3/1,6 D-Glucan

Beta-glucan supplements in the EU and U.S. usually contain insoluble beta 1,3/1,6 D-glucan derived from baker’s yeasts (Saccharomyces cerevisiae). The digits 1,3 and 6 identify positions of carbons in glucose molecules involved in bonds.

In one study, yeast derived beta 1,3/1,6 glucan decreased blood LDL levels for 8% and increased HDL levels for 16%, but there was no control group involved, so the results are questionable [1]. Yeast-derived beta-glucan, which is insoluble and of low viscosity, does not likely significantly reduce glucose spikes after carbohydrate meals.

Supplements containing oat- and barley-derived beta-glucan are also available.

Insufficient Evidence

Insufficient studies have been done to prove the effect of beta-glucans from any source in prevention or treatment of obesity [8,18], cancer [8,12], upper respiratory tract infections (common cold, flu) [13], high blood pressure (except in obese people) [15], ulcerative colitis [16], high blood glucose levels  and diabetes [2,3,4,17], fibromyalgia, chronic fatigue syndrome (CFS), rheumatoid arthritis, HIV/AIDS, wrinkles, liver problems, multiple sclerosis, asthma, allergies or physical and emotional stress. There is insufficient scientific evidence about the effectiveness of medicinal mushrooms Maitake (Grifola frondosa) or Shiitake (Lentinula edodes), containing beta 1,3/1,6 D-glucan, in treatment of any disease [19,20]. There is insufficient evidence about the effect of beta glucan on weight loss [8,18].

Beta-Glucan Safety

Beta-glucan derived from mushrooms [21] and barley [24] is Generally Considered As Safe (GRAS) by the US Food and Drug Administration (FDA); FDA has not determined the GRAS status for baker’s yeast [22] and oat bran [23], but it has approved its use.

During Pregnancy

Not enough studies have been done to determine safety of beta-glucan during pregnancy and breastfeeding [19].

Side Effects

When consuming in high amounts, beta-glucan may cause mild abdominal bloating and excessive gas (flatulence) [24]. Allergic reactions to beta-glucan are possible [24].

Frequently Asked Questions

1. Is barley vegan and gluten-free?

  • Yeast-derived beta-glucan is not vegan but is gluten-free.
  • Barley-derived beta-glucan is vegan but may not be gluten-free.
  • Oat-derived beta-glucan is vegan and, when not contaminated by wheat during processing, should be gluten-free.

Related Nutrients

  1. Kim SJ, 2006, Biomedical Issues of Dietary fiber β-Glucan  PubMed Central
  2. Braaten JT et al, 1994, High beta-glucan oat bran and oat gum reduce postprandial blood glucose and insulin in subjects with and without type 2 diabetes  PubMed
  3. Keogh GF et al, 2003, Randomized controlled crossover study of the effect of a highly β-glucan–enriched barley on cardiovascular disease risk factors in mildly hypercholesterolemic men  The American Journal of Clinical Nutrition
  4. McIntosh GH et al, 1991, Barley and wheat foods: influence on plasma cholesterol concentrations in hypercholesterolemic men  The American Journal of Clinical Nutrition
  5. Naumann E et al, 2006, β-Glucan incorporated into a fruit drink effectively lowers serum LDL-cholesterol concentrations  The American Journal of Clinical Nutrition
  6. Braaten JT et al, 1994, Oat beta-glucan reduces blood cholesterol concentration in hypercholesterolemic subjects  PubMed
  7. Wolever TMS et al, 2010, Physicochemical properties of oat β-glucan influence its ability to reduce serum LDL cholesterol in humans: a randomized clinical trial  The American Journal of Clinical Nutrition
  8. Chan GFC et al, 2009, The effects of β-glucan on human immune and cancer cells  PubMede Central
  9. 2013, Guidance for Industry: A Food Labeling Guide (11. Appendix C: Health Claims)  US Food and Drug Administration
  10. Davidson MH et al, 1991, The hypocholesterolemic effects of beta-glucan in oatmeal and oat bran. A dose-controlled study  PubMed
  11. Daniëlle AJM Kerckhoffs et al, 2003, Cholesterol-lowering effect of β-glucan from oat bran in mildly hypercholesterolemic subjects may decrease when β-glucan is incorporated into bread and cookies  The American Journal of Clinical Nutrition
  12. Maitake Mushroom  American Cancer Society
  13. Nieman DC et al, 2008, Beta-glucan, immune function, and upper respiratory tract infections in athletes  PubMed
  14. Talati R et al, 2009, The Effects of Barley-Derived Soluble Fiber on Serum Lipids  PubMed Central
  15. Maki KC, 2007, Effects of consuming foods containing oat beta-glucan on blood pressure, carbohydrate metabolism and biomarkers of oxidative stress in men and women with elevated blood pressure  PubMed
  16. Nyman EM, 2003, Importance of processing for physico-chemical and physiological properties of dietary fibre  PubMed
  17. Chen J et al, 2008, Beta-glucans in the treatment of diabetes and associated cardiovascular risks  PubMed Central
  18. El Khoury et al, 2012, Beta Glucan: Health Benefits in Obesity and Metabolic Syndrome  PubMed Central
  19. Beta-glucans  WebMD
  20. Barley facts  Barleyfoods.org
  21. US Food and Drug Administration
  22. US Food and Drug Administration
  23. US Food and Drug Administration
  24. US Food and Drug Administration

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