Research indicates that beta-1,3-glucan, a key factor for the cholesterol-lowering effect of oat bran, is very effective at activating white blood cells known as macrophages and neutrophils. These cells provide one of the immune system's first lines of defense against foreign invaders. A beta-glucan-activated macrophage or neutrophil can recognize and kill tumor cells, remove cellular debris resulting from oxidative damage, speed up recovery of damaged tissue, and further activate other components of the immune system . . .What Is Beta-Glucan?Beta-glucan
is a fiber-type polysaccharide (complex sugar) derived from the cell wall of baker's yeast, oat and barley fiber, and many medicinal mushrooms, such as maitake. In their natural state, yeast and mushrooms contain a mixture of beta-1,3-glucan and beta-1,6-glucan. Oats and barley contain a mixture of beta-1,3-glucan and beta-1,4-glucan. In addition to purified beta-1,3-glucan from these sources, you may see products listed as beta-1,3/1,6-glucan in the case of yeast-derived products and as beta-1,3/1,4-glucan when derived from oats. Similar (if not identical) properties have been shown for beta-glucanrich extracts and purified beta-glucan derived from oats, baker's yeast, and mushrooms. The two primary uses of beta-glucan are to enhance the immune system and to lower blood cholesterol levels.
Numerous experimental studies in test tubes and animals have shown beta-glucan to activate white blood cells.1 2 3 4 5
In fact, there have been hundreds of research papers on beta-glucan since the 1960s.6
The research indicates that beta-1,3-glucan, in particular, is very effective at activating white blood cells known as macrophages and neutrophils. These cells provide one of the immune system's first lines of defense against foreign invaders. A beta-glucanactivated macrophage or neutrophil can recognize and kill tumor cells, remove cellular debris resulting from oxidative damage, speed up recovery of damaged tissue, and further activate other components of the immune system.7 8
Although the research in test tube and animal studies is promising, many questions remain about the effectiveness of beta-glucan as an oral supplement to enhance immune function in humans.
Beta-glucan is the key factor for the cholesterol-lowering effect of oat bran.9 10 11 12 13
As with other soluble-fiber components, the binding of cholesterol (and bile acids) by beta-glucan and the resulting elimination of these moleculesin, the feces is very helpful for reducing blood cholesterol.14 15 16
Results from a number of double-blind trials with either oat- or yeast-derived beta-glucan indicate typical reductions, after at least four weeks of use, of approximately 10% for total cholesterol and 8% for LDL ("bad") cholesterol, with elevations in HDL ("good") cholesterol ranging from zero to 16%.17 18 19 20 21
Like other sources of soluble fiber, beta-glucan is, according to preliminary studies, helpful in reducing the elevation in blood sugar levels that typically follow a meal.22 23 24 25
Beta-glucan produces this effect by delaying gastric emptying so that dietary sugar is absorbed more gradually, as well as by possibly increasing the tissue sensitivity to insulin. These effects suggest possible benefit in blood sugar control in people with diabetes.Where is it found?
Beta-glucan is found in the cell walls of many yeast and cereal fibers, such as oats, wheat, and barley. As a dietary supplement, beta-glucan is available in liquid form as well as in capsules and tablets.
Beta-glucan has been used in connection with the following conditions:
- High cholesterol (Reliable and relatively consistent scientific data showing a substantial health benefit.)
Who is likely to be deficient?
- Immune enhancement (An herb is primarily supported by traditional use, or the herb or supplement has little scientific support and/or minimal health benefit.)
Because beta-glucan is not an essential nutrient, deficiencies do not occur.How much is usually taken?
For lowering cholesterol levels, the amount of beta-glucan used in clinical trials has ranged from 2,900 to 15,000mg per day. For enhancing immune function, an effective amount has not yet been determined due to the lack of studies in this application. However, manufacturers of beta-glucan products usually recommend between 50 and 1,000mg daily (to be taken on an empty stomach), although some products contain as much as 500mg per capsule.Are there any side effects or interactions?
No side effects have been reported.
At the time of writing, there were no well-known drug interactions with beta-glucan.References:
1. Czop JK. The role of beta-glucan receptors on blood and tissue leukocytes in phagocytosis and metabolic activation. Pathol Immunopathol Res 1986;5:28696.
2. Wakshull E, Brunke-Reese D, Lindermuth J, et al. PGG-glucan, a soluble beta-(1,3)-glucan, enhances the oxidative burst response, microbicidal activity, and activates an NF-kappa B-like factor in human PMN: evidence for a glycosphingolipid beta-(1,3)-glucan receptor. Immunopharmacology 1999;41:89107.
3. Czop JK, Kay J. Isolation and characterization of beta-glucan receptors on human mononuclear phagocytes. J Exp Med 1991;173:151120.
4. Czop JK, Puglisi AV, Miorandi DZ, Austen KF. Perturbation of beta-glucan receptors on human neutrophils initiates phagocytosis and leukotriene B4 production. J Immunol 1988;141:31706.
5. Estrada A, Yun CH, Van Kessel A, et al. Immunomodulatory activities of oat beta-glucan in vitro and in vivo. Microbiol Immunol 1997;41:9918.
6. Ooi VE, Liu F. Immunomodulation and anti-cancer activity of polysaccharide-protein complexes. Curr Med Chem 2000;7:71529 [review].
7. Ross GD, Vetvicka V, Yan J, et al. Therapeutic intervention with complement and beta-glucan in cancer. Immunopharmacology 1999;42:6174.
8. Di Renzo L, Yefenof E, Klein E. The function of human NK cells is enhanced by beta-glucan, a ligand of CR3 (CD11b/CD18). Eur J Immunol 1991 Jul;21:17558.
9. Bell S, Goldman VM, Bistrian BR, et al. Effect of beta-glucan from oats and yeast on serum lipids. Crit Rev Food Sci Nutr 1999;39:189202 [review].
10. Bell S, Goldman VM, Bistrian BR, et al. Effect of beta-glucan from oats and yeast on serum lipids. Crit Rev Food Sci Nutr 1999;39:189202 [review].
11. Behall KM, Scholfield DJ, Hallfrisch J. Effect of beta-glucan level in oat fiber extracts on blood lipids in men and women. J Am Coll Nutr 1997;16:4651.
12. Braaten JT, Wood PJ, Scott FW, et al. Oat beta-glucan reduces blood cholesterol concentration in hypercholesterolemic subjects. Eur J Clin Nutr 1994;48:46574.
13. Davidson MH, Dugan LD, Burns JH, et al. The hypocholesterolemic effects of beta-glucan in oatmeal and oat bran. A dose-controlled study. JAMA 1991;265:18339.
14. Wood PJ. Physicochemical properties and physiological effects of the (1----3)(1----4)-beta-D-glucan from oats. Adv Exp Med Biol 1990;270:11927.
15. Uusitupa MI, Miettinen TA, Sarkkinen ES, et al. Lathosterol and other non-cholesterol sterols during treatment of hypercholesterolaemia with beta-glucan-rich oat bran. Eur J Clin Nutr 1997;51:60711.
16. Lia A, Hallmans G, Sandberg AS, et al. Oat beta-glucan increases bile acid excretion and a fiber-rich barley fraction increases cholesterol excretion in ileostomy subjects. Am J Clin Nutr 1995;62:124551.
17. Bell S, Goldman VM, Bistrian BR, et al. Effect of beta-glucan from oats and yeast on serum lipids. Crit Rev Food Sci Nutr 1999;39:189202 [review].
18. Nicolosi R, Bell SJ, Bistrian BR, et al. Plasma lipid changes after supplementation with beta-glucan fiber from yeast. Am J Clin Nutr 1999;70:20812.
19. Behall KM, Scholfield DJ, Hallfrisch J. Effect of beta-glucan level in oat fiber extracts on blood lipids in men and women. J Am Coll Nutr 1997;16:4651.
20. Braaten JT, Wood PJ, Scott FW, et al. Oat beta-glucan reduces blood cholesterol concentration in hypercholesterolemic subjects. Eur J Clin Nutr 1994;48:46574.
21. Uusitupa MI, Ruuskanen E, Makinen E, et al. A controlled study on the effect of beta-glucan-rich oat bran on serum lipids in hypercholesterolemic subjects: relation to apolipoprotein E phenotype. J Am Coll Nutr 1992;11:6519.
22. Braaten JT, Scott FW, Wood PJ, et al. High beta-glucan oat bran and oat gum reduce postprandial blood glucose and insulin in subjects with and without type 2 diabetes. Diabet Med 1994;11:3128.
23. Wood PJ. Physicochemical properties and physiological effects of the (1----3)(1----4)-beta-D-glucan from oats. Adv Exp Med Biol 1990;270:11927.
24. Bourdon I, Yokoyama W, Davis P, et al. Postprandial lipid, glucose, insulin, and cholecystokinin responses in men fed barley pasta enriched with beta-glucan. Am J Clin Nutr 1999;69:5563.
25. Pick ME, Hawrysh ZJ, Gee MI. Oat bran concentrate bread products improve long-term control of diabetes: a pilot study. J Am Diet Assoc 1996;96:125461.
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