Scientific Name(s): Hordeum vulgare L.
Common Name(s): Barley, Hordeum, Prowashonupana
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.PLANTS 2009, Purdue 2009
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.Facciola 1990, Reader's Digest 1986, Schauenberg 1990
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 × 106 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.Würsch 1997, Keagy 2001
The major nutrient in barley is starch, with smaller amounts of protein and fats also present.NutritionData 2009 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.McGough 2005, Vader 2003 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.NutritionData 2009 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.Mahdi 1995 Other components that have been associated with health benefits include tocotrienol, lignan, phytoestrogen, phenolic compounds, and phytic acid.Li 2003, Madhujith 2007 Barley is the source of a natural sweetener known as malt sugar or barley jelly sugar, which is high in maltose.Facciola 1990
Uses and Pharmacology
Barley grass is consumed largely because of its nutritional content. Barley has been shown to lower cholesterol and to have 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 and starch content of the grain depends on several factors, including the barley cultivar and food processing techniques. Possible methods for increasing intake of beta-glucans and low-glycemic starch (ie, amylose) include the use of barley cultivars containing elevated content levels (ie, Prowashonupana barley and genotype SH99250, respectively), or encapsulation or incorporation of enriched barley flour fractions into products such as breads, pasta, tortillas, 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. Ames 2008, Ames 2015, Fredlund 2003, Keagy 2001, Livesey 1995
A ground, roasted barley soup prepared with milk and honey (Talbinah), used historically by Arabs to relieve depression, was evaluated in a 7-week randomized cross-over trial for its effects in 30 depressed (Geriatric Depression Scale-Residential 3 or higher) elderly subjects in a long-term care facility. Depressive symptoms, mood disturbances, and changes in mood were assessed using interview-based validated scales; standard institutional meals were given alone or with Talbinah (25 g per 100 mL water once daily). Statistically significant improvements were documented in 9 of the 11 mean scores measuring depression, stress, anxiety, and mood disturbances.Badrasawi 2013
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.Ames 2008, Würsch 1997
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.Li 2003
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.Alminger 2008, Bourdon 1999, Casiraghi 2006, Granfeldt 1994, Jang 2001, Liljeberg 1994, Poppitt 2007 Similarly, trials conducted in patients with type 2 diabetes have shown reduced glycemic responses to barley-enriched breakfast meals.Ames 2008, Rendell 2005 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.Biörklund 2005, Li 2003, Rendell 2005
The ability of a variety of oat and barley food products to lower postprandial blood glucose was evaluated in a 2013 meta-analysis of 34 human studies; patients with type 2 diabetes mellitus (including noninsulin-dependent diabetes mellitus) were excluded as were trials that employed low viscosity extracts or deliberately depolymerized beta-glucan. A dose of at least 3 g beta-glucan per meal of intact oats or barley (cooked or fermented), or at least 4 g soluble beta-glucan (with a molecular weight greater than 250,000 g/mol) in processed oat and barley food products, which provided 30 to 80 g of available carbohydrate, was sufficient to produce a physiologically relevant reduction (at least −27 mmol min/L) in postprandial blood glucose. Glycemic response was greater for intact grains than for processed foods. The efficacy rate and average reduction in area under the curve (AUC), respectively, were as follows: intact kernel foods (96%, −99 mmol min/L); raw flours, flakes and bran in beverages or puddings (75%, −75 mmol min/L); muffin batter (92%, −60 mmol min/L); dry cereal products (82%, −32 mmol min/L); and breads (64%, −29 mmol min/L). Oat and barley products were not significantly different with respect to average reduction in AUC or glycemic index.Tosh 2013
The effect of fiber and/or starch composition in barley tortillas on postprandial glucose and insulin as well as satiety hormones (ie, incretin glucagon-like peptide-1 [GLP-1] and peptide YY [PYY]) was evaluated in a randomized, double-blind, controlled trial in healthy young adults (n = 12). A consistent carbohydrate content of 50 g was provided in each tortilla; fiber and starch levels were varied as follows: amylose (0% and 42%), beta-glucan (4.5 g, 7.8 g, and 11.6 g), and insoluble fiber (7.4 g and 19.6 g). Neither the amylose (starch) nor insoluble fiber variations altered postprandial glucose or insulin; however, high beta-glucan tortillas significantly reduced incremental AUC of postprandial glucose and insulin compared with those with low beta-glucan. Additionally, tortillas with high insoluble fiber caused a higher AUC for GLP-1 compared with the low insoluble fiber ones. No significant effects were documented for PYY.Ames 2015
Data from studies assessing oat and barley beta-glucan effects on blood glucose levels, as well as cholesterol levels, were analyzed in a 2011 meta-analysis that included subjects with or without health conditions. Of the 126 eligible studies, 44 studied barley beta-glucan. Daily beta-glucan doses ranged from 2 to 14 g/day. Analysis revealed a significant reduction in blood glucose (−2.58 mmol/L); heterogeneity was high. A beta-glucan dose of 1 g/day resulted in a change in blood glucose of −0.084 mmol/L, but showed uncertain changes in blood glucose levels with changes in beta-glucan dosage.Tiwari 2011
A meta-analysis of randomized controlled trials has assessed the effect of beta-glucan extract on glycemic control and insulin sensitivity in patients with or without diabetes. A total of 18 trials met inclusion criteria; 7 trials (N=423) utilized beta-glucan extract. All 7 studies used beta-glucan extracted from cereals (oats, oat bran, barley) and the dose of the extract ranged from 3 to 10 g/day for up to 8 weeks. Significant heterogeneity was observed among the studies and subgroup analysis found the variability in study results to be impacted by study location (significant benefit associated with studies conducted in Asian but not Western countries), type of study (benefit in parallel but not crossover designs), participant health status (benefit in type 2 diabetics and hyperlipidemics), and duration of intervention (less than 8 weeks vs 8 weeks). Overall, beta-glucan extract was not as effective as whole oats in reducing HbA1c, fasting blood glucose, or insulin sensitivity.He 2016
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.Biörklund 2005 Limited trial data exist to support GI therapeutic claims.Li 2003, Lupton 1993
A 2013 randomized crossover trial evaluated the effects of 60 g/day of whole-grain barley, brown rice, or a combination of the 2 grains on fecal microbial ecology, inflammation, glucose, and lipid metabolism in 28 healthy, nonvegetarian volunteers. All end points were significantly improved, especially with consumption of whole-grain barley as well as the combination of the 2 grains. Fecal bacterial diversity was increased by all 3 treatments; however, the interindividual variation was substantial. Changes in gut microbiota coincided with improvements in metabolic and immunological processes. The anti-inflammatory effect was confirmed with a significant reduction in plasma interleukin (IL)-6, which was greatest in overweight individuals, and was decreased significantly in women by all 3 test meals. The greatest IL-6 reductions were associated with significantly higher proportions of Dialister species and lower proportions of Coriobacteriaceae in the gut (bacterial groups that have been linked to chronic inflammation). Additionally, the presence of Ruminococcaceae in the gut was negatively correlated with inflammation markers and was observed to be more dominant in subjects who were not overweight. Glucose metabolism also improved significantly, especially in obese subjects and female subjects, and total cholesterol was significantly reduced in women.Martínez 2013
A randomized controlled trial in 41 ulcerative colitis patients in remission documented significant reductions in pro-inflammatory cytokines (IL-6 and IL-8) when standard therapy was supplemented with 30 g/day of germinated barley foodstuff for 2 months while levels of these cytokines increased in the control group.Faghfoori 2011
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.Shuren 2009 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.Lupton 1994
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.Delaney 2003 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.Li 2003 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.
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.Ames 2008, Behall 2004, Keenan 2007, Lupton 1994, Shimizu 2008 However, a number of studies have been unable to demonstrate changes in lipid profiles.Biörklund 2005, Ikegami 1996, Keogh 2003 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.Biörklund 2005, Smith 2008
In a 2011 meta-analysis that included subjects with or without health conditions, significant reductions occurred in total cholesterol, LDL, and triglycerides/triacylglycerol after beta-glucan consumption. Of the 126 eligible studies, 44 studied barley beta-glucan. Daily beta-glucan doses ranged from 1.2 to 10 g/day in total cholesterol studies. Analysis revealed a significant dose-response reduction in total cholesterol with 1 g/day yielding a −0.079 mmol/L change, but no significant dose-response relation was noted for LDL, high-density lipoprotein, or triglycerides/triacylglycerol.Tiwari 2011 Other meta-analyses of randomized clinical trials conducted in hypercholesterolemic and healthy participants support significant reductions in total cholesterol and LDL with supplementation of barley and/or beta-glucan from barley into food products, regardless of dietary backgrounds.AbuMweis 2010, Talati 2009 Additionally, in a randomized, controlled crossover trial, a 4-week diet enriched with 274 g/day of barley kernels (whole-grain kernels and kernel bread) plus 168 g/day of legumes significantly improved a number of cardiometabolic risk factors in overweight healthy women over 50 years of age. Significantly greater improvements in total and LDL-cholesterol were documented with this whole-grain barley kernel plus legume diet than the energy and macronutrient matched wheat-based diet.Tovar 2014
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.Tariq 2000 The test diet consisted of precooked barley, dried lentils, peas, and beans, plus oat bran and a commercial breakfast cereal enriched with psyllium.
Most trials evaluating effects on cholesterol have used dosages ranging from 3 to 10 g/day barley beta-glucan.Ames 2008 An intake of at least 3 g/day of barley beta-glucan is suggested for lowering cholesterol.Würsch 1997
Pregnancy / Lactation
Information regarding safety and efficacy in pregnancy and lactation is lacking.
None well documented.
Urticaria from beer is an immunoglobulin E–mediated hypersensitivity reaction induced by a protein component of approximately 10 kDa derived from barley.Curioni 1999 Beer contains hordein at a concentration of 1.12 g/servingDenke 2000 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.Vader 2003, McGough 2005 Hordeins have been implicated as a trigger for celiac disease, and barley should be avoided by people with this disorder.
There is little or no information regarding the toxicology of barley.
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