Barley

Scientific Name(s): Hordeum vulgare L. Family: Poaceae

Common Name(s): Barley , hordeum , Prowashonupana

Uses

Barley is a food staple and is also brewed into beer, fermented to make miso, and processed to yield malt sugar. Although there is not a consensus, some studies indicate that barley reduces cholesterol (to a similar degree as that of oats), and a few small studies demonstrated a possible protective role in hyperglycemia.

Dosing

The recommended intake of barley beta-glucan for cholesterol-lowering action is 3 g/day.

Contraindications

Patients with celiac disease should avoid consumption of barley products.

Pregnancy/Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking.

Interactions

None well documented.

Adverse Reactions

Hypersensitivity reactions may occur in sensitive individuals.

Toxicology

There is little or no information.

Botany

Barley is an annual grass grown in winter or spring. The winter annual is planted in the fall because it requires a period of exposure to cold in order to produce flowers and set seeds. It forms a rosette type of sprout in fall and winter, developing elongated stems and flower heads in early summer. Spring varieties do not have a typical rosette stage and are grown in areas with very cold winters. The stems are round and hollow between the nodes, and vary in length from 30 to 122 cm. The flowers and, later, the mature seeds are borne on spikes attached to the central stem. Depending on the variety and climatic conditions, the period from flowering until harvest lasts 40 to 55 days. 1 , 2

History

Barley is one of the first domesticated grains; the use of barley for food and medicinal purposes dates to antiquity. The ancient Greeks used the mucilage derived from the cereal (known as ptisane) to treat gastrointestinal (GI) inflammation. Gladiators ate barley for strength and stamina, and the Roman physician Gaius Plinius Secundus (known as Pliny the Elder, AD 23-79) used barley as part of a ritualized cure for boils. Barley is the fourth most important grain crop in the United States, and is used mainly as livestock feed. Although supplanted by wheat and rye in baking, barley is used extensively in soups, cereals, animal feed, and beer production. Protein extracted from the leaves is believed to be an adequate food supplement. Roasted seeds are used in making coffee, and fermented seeds are made into miso. Whole barley is used for animal feed and malting. For human consumption, the barley hull is removed by abrasion, producing pearl barley. 3 , 4 , 5

Chemistry

Barley contains about 3% to 11% dietary fiber made up of pentosans, beta-glucan, and cellulose. Beta-glucan is a highly viscous soluble polysaccharide, with a linear, unbranched structure composed of 4-O-linked beta-D-glucopyranosyl units and 3-O-linked beta-D-glucopyranosyl units; the molecular weight ranges from 0.4 to 2.3 × 10 6 Da. Beta-glucan is associated with the plant cell wall and is distributed throughout the kernel, with a slightly higher concentration in the outer portion. 6 , 7

The major nutrient in barley is starch, with smaller amounts of protein and fats also present. 8 About half of the total protein content is made up of storage proteins known as hordeins. These belong to the prolamin group and are closely related to the gluten found in wheat. Hypersensitivity to barley has been attributed to these proteins. 9 , 10 Barley bran flour consists of dried and milled brewers grain, the insoluble portion of malted barley after the removal of soluble carbohydrates. The flour contains only 1% to 3% soluble fiber, as most is lost in the processing.

Although some essential amino acids and vitamins found in the outer layers of the seed are lost during the pearling process, pearl barley is rich in B-group vitamins and is a good source of trace elements including iron, magnesium, zinc, selenium, and copper. 8 Chromium levels, up to 10 times higher than those found in brewer's yeast (generally regarded as the richest natural source of chromium), have been recorded in some cultivars. 11 Other components that have been associated with health benefits include tocotrienol, lignan, phytoestrogen, phenolic compounds, and phytic acid. 12 , 13 Barley is the source of a natural sweetener known as malt sugar or barley jelly sugar, which is high in maltose. 5

Uses and Pharmacology

Barley grass is consumed largely because of its nutritional content. Barley has been shown to lower cholesterol and has an effect on blood glucose and insulin levels. However, it is usually consumed in relatively small quantities, and incorporating sufficient barley into the diet to produce these effects is difficult. Additionally, the beta-glucan content of the grain depends on several factors, including the barley cultivar and food processing techniques. Possible methods for increasing intake of beta-glucans include the use of barley cultivars containing elevated content levels (eg, Prowashonupana barley), or encapsulation or incorporation of enriched barley flour fractions into products such as breads, pasta, and muffins. The physical form and treatment of the grain during processing appear to affect the digestion of the barley starch and the absorption of various trace elements, such as zinc. 7 , 14 , 15 , 16

Hyperlipidemia

A final ruling on permissible health claims for the role of barley soluble fiber in reducing the risk of cardiovascular disease was issued by the Food and Drug Administration in August 2008, and barley now joins oats and other soluble fibers regarded as low-density lipoprotein (LDL), cholesterol-lowering agents. 17 Although the precise mechanism is unclear, it is thought that beta-glucan regulates the rate and site of lipid and carbohydrate digestion and absorption. Postulated mechanisms include increased viscosity in the GI tract, delay in cholesterol absorption, and increased conversion of cholesterol into bile acids. The cholesterol-lowering activities of barley are usually attributed to the beta-glucan fraction of the grain; however, barley oil also has shown cholesterol-lowering properties. 18

Animal data

Concentrated beta-glucan preparations from barley lowered serum cholesterol in animal models. The effects of concentrated beta-glucan on plasma lipids and lipoprotein, hepatic cholesterol, fecal excretion of neutral steroids, and atherogenesis were studied in hamsters consuming a hypercholesterolemic diet. 19 Improvements in all parameters occurred and were dose dependent. Lipid metabolism was significantly better in diabetic rats fed a barley diet than those receiving low fiber, rice, or cornstarch diets in another study. 20 The fiber content of the barley diet was very high (1.79 g/day); this corresponds to a human dosage of about 42 to 73 g/day.

Clinical data

The results of clinical studies have been mixed, but largely demonstrate positive findings. Reductions in LDL and total cholesterol, as well as reductions in cholesterol and high-density lipoprotein ratios, have been shown in a number of trials conducted in hypercholesterolemic patients. 16 , 18 , 21 , 22 , 23 However, a number of studies have been unable to demonstrate changes in lipid profiles. 24 , 25 , 26 One reason proposed for the negative findings is the molecular weight of the beta-glucan used in the trial, with positive results being attributed to higher molecular weight glucan content. 24 , 27

Diabetes mellitus

Meals high in soluble fiber reduced the rise in postprandial blood glucose and insulin concentrations. These effects were attributed to an increase in the viscosity of the contents of the stomach and small intestine, thus reducing the absorption rate of the digested nutrients. 6 , 16

Animal data

Long-term improvements in glucose tolerance, fasting plasma glucose, and glycosylated hemoglobin levels were demonstrated in diabetic rats receiving a barley diet for 9 months, and attributed to the high fiber content of the barley diet. Results from rats fed rice and cornstarch diets that differed from the test diet only in fiber content were worse after the third month of the study. 20

Clinical data

Few trials have been conducted using barley beta-glucan in diabetic populations, with most available data based on trials in healthy volunteers.

Most trials evaluated the postprandial effect of a barley-enriched breakfast meal (30% of the carbohydrates in the control diet were replaced by barley) and consistently found positive effects on blood glucose and insulin responses. 28 , 29 , 30 , 31 , 32 , 33 , 34 Similarly, trials conducted in patients with type 2 diabetes have shown reduced glycemic responses to barley-enriched breakfast meals. 16 , 35 A limited number of trials have not established a positive response, notably when using barley beta-glucan as a drink rather than a grain-based meal. 12 , 24 , 35

Other uses
GI effects

Beta-glucan is fermented by the intestinal microflora to form short-chain fatty acids important for the protection of colonic mucosa. Additionally, the starch in barley is an important precursor of butyric acid, a substance that has an essential function in maintaining the health of the colonic mucosa, particularly against inflammatory conditions and those associated with abnormal cell proliferation. 24 Limited trial data exist to support GI therapeutic claims. 12 , 36

Prostate

A diet high in soluble fiber, including barley, resulted in a small but statistically significant reduction in serum prostate specific antigen in healthy men with hyperlipidemia. 37 The test diet consisted of precooked barley, dried lentils, peas, and beans, plus oat bran and a commercial breakfast cereal enriched with psyllium.

Dosage

Most trials evaluating effects on cholesterol have used dosages ranging from 3 to 10 g/day barley beta-glucan. 16 An intake of at least 3 g/day of barley beta-glucan is suggested for lowering cholesterol. 6

Pregnancy/Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking.

Interactions

None well documented.

Adverse Reactions

Several cases of hypersensitivity to barley have been reported, including dermatitis, asthma, and life-threatening recurrent anaphylaxis. 38 , 39 , 40 , 41

Urticaria from beer is an immunoglobulin E–mediated hypersensitivity reaction induced by a protein component of approximately 10 kDa derived from barley. 42 Beer contains hordein at a concentration of 1.12 g/serving, 43 an amount sufficient to exacerbate symptoms of celiac disease in some individuals.

Like gluten, hordein belongs to the group prolamins, a family of cereal grain storage proteins rich in glutamine and proline. Cross-reactivity between gluten peptides and related hordein peptides has been established. 9 , 10 Hordeins have been implicated as a trigger for celiac disease, and barley should be avoided by people with this disorder.

Toxicology

There is little or no information regarding the toxicology of barley.

Bibliography

1. Hordeum vulgare . USDA, NRCS. 2009. The PLANTS Database ( http://plants.usda.gov , March 2009). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.
2. Barley. Purdue University Center for New Crops and Plants Products. http://www.hort.purdue.edu/newcrop/Crops/Barley.html . Updated February 18, 1999. Accessed July 24, 2009.
3. Schauenberg P, Paris F. Guide to Medicinal Plants . New Canaan, CT: Keats Publishing; 1990.
4. Magic and Medicine of Plants . Pleasantville, NY: Readers Digest Association; 1986.
5. Facciola S. Cornucopia: A Source Book of Edible Plants . Vista, CA: Kampong Publications; 1990.
6. Würsch P, Pi-Sunyer FX. The role of viscous soluble fiber in the metabolic control of diabetes. A review with special emphasis on cereals rich in β-glucan. Diabetes Care . 1997;20(11):1774-1780.
7. Keagy PM, Knuckles BE, Yokoyama WH, Kahlon TS, Hudson CA. Health-promoting properties of a high beta-glucan barley fraction [Grains symposium, part two]. Nutr Today . 2001;36(3):121-123.
8. Nutrition facts and food composition analysis for barley, pearled, cooked. NutritionData.com. http://www.nutritiondata.com/facts/cereal-grains-and-pasta/5680/2 . Accessed July 24, 2009.
9. Vader LW, Stepniak DT, Bunnik EM, et al. Characterization of cereal toxicity for celiac disease patients based on protein homology in grains. Gastroenterology . 2003;125(4):1105-1113.
10. McGough N, Cummings JH. Coeliac disease: a diverse clinical syndrome caused by intolerance of wheat, barley and rye. Proc Nutr Soc . 2005;64(4):434-450.
11. Mahdi GS. Barley as high-chromium food. J Am Diet Assoc . 1995;95(7):749.
12. Li J, Kaneko T, Qin LQ, Wang J, Wang Y. Effects of barley intake on glucose tolerance, lipid metabolism, and bowel function in women. Nutrition . 2003;19(11-12):926-929.
13. Madhujith T, Shahidi F. Antioxidative and antiproliferative properties of selected barley ( Hordeum vulgarae L.) cultivars and their potential for inhibition of low-density lipoprotein (LDL) cholesterol oxidation. J Agric Food Chem . 2007;55(13):5018-5024.
14. Livesey G, Wilkinson JA, Roe M, et al. Influence of the physical form of barley grain on the digestion of its starch in the human small intestine and implications for health. Am J Clin Nutr . 1995;61(1):75-81.
15. Fredlund K, Bergman EL, Rossander-Hulthén L, Isaksson M, Almgren A, Sandberg AS. Hydrothermal treatment and malting of barley improved zinc absorption but not calcium absorption in humans. Eur J Clin Nutr . 2003;57(12):1507-1513.
16. Ames NP, Rhymer CR. Issues surrounding health claims for barley. J Nutr . 2008;138(6):1237S-1243S.
17. Shuren J; US Department of Health and Human Services. Federal register final rule 73 FR 47828 August 15, 2008: food labeling: health claims; soluble fiber from certain foods and risk of coronary heart disease. US Food and Drug Administration Web site. http: / / www.fda.gov / Food / LabelingNutrition / LabelClaims / HealthClaimsMeetingSignificantScientificAgreementSSA / ucm074245.htm . Published August 15, 2008. Updated April 30, 2009. Accessed August 3, 2009.
18. Lupton JR, Robinson MC, Morin JL. Cholesterol-lowering effect of barley bran flour and oil. J Am Diet Assoc . 1994;94(1):65-70.
19. Delaney B, Nicolosi RJ, Wilson TA, et al. β-glucan fractions from barley and oats are similarly antiatherogenic in hypercholesterolemic Syrian golden hamsters. J Nutr . 2003;133(2):468-475.
20. Li J, Kaneko T, Qin LQ, Wang J, Wang Y, Sato A. Long-term effects of high dietary fiber intake on glucose tolerance and lipid metabolism in GK rats: comparison among barley, rice, and cornstarch. Metabolism . 2003;52(9):1206-1210.
21. Behall KM, Scholfield DJ, Hallfrisch J. Lipids significantly reduced by diets containing barley in moderately hypercholesterolemic men. J Am Coll Nutr . 2004;23(1):55-62.
22. Keenan JM, Goulson M, Shamliyan T, Knutson N, Kolberg L, Curry L. The effects of concentrated barley β-glucan on blood lipids in a population of hypercholesterolaemic men and women [published correction in Br J Nutr . 2007;98(2):445]. Br J Nutr . 2007;97(6):1162-1168.
23. Shimizu C, Kihara M, Aoe S, et al. Effect of high β-glucan barley on serum cholesterol concentrations and visceral fat area in Japanese men—a randomized, double-blinded, placebo-controlled trial. Plant Foods Hum Nutr . 2008;63(1):21-25.
24. Biörklund M, van Rees A, Mensink RP, Onning G. Changes in serum lipids and postprandial glucose and insulin concentrations after consumption of beverages with β-glucans from oats or barley: a randomized dose-controlled trial. Eur J Clin Nutr . 2005; 59(11):1272-1281.
25. Keogh GF, Cooper GJ, Mulvey TB, et al. Randomized controlled crossover study of the effect of a highly β-glucan-enriched barley on cardiovascular disease risk factors in mildly hypercholesterolemic men. Am J Clin Nutr . 2003;78(4):711-718.
26. Ikegami S, Tomita M, Honda S, et al. Effect of boiled barley-rice-feeding in hypercholesterolemic and normolipemic subjects. Plant Foods Hum Nutr . 1996;49(4):317-328.
27. Smith KN, Queenan KM, Thomas W, Fulcher RG, Slavin JL. Physiological effects of concentrated barley β-glucan in mildly hypercholesterolemic adults. J Am Coll Nutr . 2008;27(3):434-440.
28. Liljeberg H, Björck I. Bioavailability of starch in bread products. Postprandial glucose and insulin responses in healthy subjects and in vitro resistant starch content. Eur J Clin Nutr . 1994;48(3):151-163.
29. Granfeldt Y, Liljeberg H, Drews A, Newman R, Björck I. Glucose and insulin responses to barley products: influence of food structure and amylose-amylopectin ratio. Am J Clin Nutr . 1994;59(5):1075-1082.
30. Bourdon I, Yokoyama W, Davis P, et al. Postprandial lipid, glucose, insulin, and cholecystokinin responses in men fed barley pasta enriched with β-glucan. Am J Clin Nutr . 1999;69(1):55-63.
31. Jang Y, Lee JH, Kim OY, Park HY, Lee SY. Consumption of whole grain and legume powder reduces insulin demand, lipid peroxidation, and plasma homocysteine concentrations in patients with coronary artery disease: randomized controlled clinical trial. Arterioscler Thromb Vasc Biol . 2001;21(12):2065-2071.
32. Alminger M, Eklund-Jonsson C: Whole-grain cereal products based on a high-fibre barley or oat genotype lower post-prandial glucose and insulin responses in healthy humans. Eur J Nutr . 2008;47(6):294-300.
33. Poppitt SD, van Drunen JD, McGill AT, Mulvey TB, Leahy FE. Supplementation of a high-carbohydrate breakfast with barley β-glucan improves postprandial glycaemic response for meals but not beverages. Asia Pac J Clin Nutr . 2007;16(1):16-24.
34. Casiraghi MC, Garsetti M, Testolin G, Brighenti F. Post-prandial responses to cereal products enriched with barley β-glucan. J Am Coll Nutr . 2006;25(4):313-320.
35. Rendell M, Vanderhoof J, Venn M, et al. Effect of a barley breakfast cereal on blood glucose and insulin response in normal and diabetic patients. Plant Foods Hum Nutr . 2005;60(2):63-67.
36. Lupton JR, Morin JL, Robinson MC. Barley bran flour accelerates gastrointestinal transit time. J Am Diet Assoc . 1993;93(8):881-885.
37. Tariq N, Jenkins DJ, Vidgen E, et al. Effect of soluble and insoluble fiber diets on serum prostate specific antigen in men. J Urol . 2000;163(1):114-118.
38. Varjonen E, Vainio E, Kalimo K. Life-threatening, recurrent anaphylaxis caused by allergy to gliadin and exercise. Clin Exp Allergy . 1997;27(2):162-166.
39. Pereira F, Rafael M, Lacerda MH. Contact dermatitis from barley. Contact Dermititis . 1998;39(5):261-262.
40. Vidal C, González-Quintela A. Food-induced and occupational asthma due to barley flour. Ann Allergy Asthma Immunol . 1995;75(2):121-124.
41. Armentia A, Rodríguez R, Callejo A, et al. Allergy after ingestion or inhalation of cereals involves similar allergens in different ages. Clin Exp Allergy . 2002;32(8):1216-1222.
42. Curioni A, Santucci B, Cristaudo A, et al. Urticaria from beer: an immediate hypersensitivity reaction due to a 10-kDa protein derived from barley. Clin Exp Allergy . 1999;29(3):407-413.
43. Denke MA. Nutritional and health benefits of beer. Am J Med Sci . 2000;320(5):320-326.

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