Foods That Safely Reduce Blood GlucoseApril 2013
By Michael Downey
As we age, one of our priorities is maintaining optimal glucose levels to avoid heart disease, cancer, and diabetes.1-5
Fortunately, many Life Extension® members use supplements, hormones, and drugs to improve their insulin sensitivity, which facilitates the more efficient removal of glucose from the blood.6-12
Less well-known, however, is the fact that there are certain foods proven to decrease blood sugar levels!7,13-16 Specifically, barley and black beans have been extensively studied for their ability to maintain glycemic control.
In this article, you will learn how these two foods have been shown to lower blood sugar and inhibit diabetes and other glycemic-stress-related problems such as cardiovascular disease and obesity.Including these two glucose-lowering foods as part of your normal diet can help maintain better blood sugar levels.
Barley Lowers Blood Sugar and Insulin Levels
Excessive dietary carbohydrates, such as white rice and potatoes, trigger surges in blood glucose, a key factor in the worldwide epidemic of type II diabetes. 17,18 Aging increases this effect—beginning as early as age 20.17
National Institutes of Health data indicate that 35% of Americans aged 20 or older have abnormally high blood glucose levels—known as prediabetes—as do 50% of those aged 65 years or older!17
Fortunately, research has established that consumption of insoluble dietary fiber—which is found in certain whole grains, including barley19—is associated with a reduced risk of type II diabetes.20
Barley is also a rich source of soluble fiber.19
In fact, one study conducted on overweight women found significantly lower insulin and glucose responses following barley ingestion, compared to ingestion of oats.15 The researchers concluded that particle size—flour versus flakes—made little difference. The reduced glucose effect was determined to be the result of the higher content of the soluble fiber in the barley.15
Another study found that, by suppressing free fatty acid levels in the blood, whole barley regulates blood sugar better than other grains—and for up to 10 hours after consumption!21
Our bodies cannot digest the viscous soluble fiber in barley, which binds with water to slow food passage through the digestive system. This tempers the body’s glucose and insulin responses after a meal.22,23
Substantial research has demonstrated that the soluble fiber in barley lowers postprandial glucose and insulin.15,23-27 This has been demonstrated not only in the more common single-meal test studies of limited duration, but also in a 12-week study that pinpointed the longer-term effects of barley consumption on non-diabetic individuals on a weight-neutral diet.28
This prospective, randomized, placebo controlled, double blind trial evaluated 50 healthy subjects without prior diagnosis of diabetes. After 12 weeks, the scientists found that daily ingestion of soluble barley fiber significantly reduced fasting serum insulin values and, during oral glucose tolerance tests, significantly lowered blood glucose responses.28
The team concluded that soluble barley fiber “may slow the deterioration of insulin sensitivity for individuals at increased risk for diabetes mellitus.”28
Barley Effects Beyond Blood Sugar
Barley improves risk factors for cardiovascular disease and stroke.
Barley fiber increases the excretion of bile acids into the intestines. Since these acids are comprised of oxidized cholesterol, this lowers total serum cholesterol.29 Studies have confirmed that barley lowers cholesterol,30 low-density lipoprotein (LDL),31,32 and blood pressure.33
Barley is a rich source of soluble and insoluble fiber—both of which benefit gastrointestinal health.
The soluble fiber in barley binds with water, adding bulk to stools and promoting regular bowel movements.34 Some of the insoluble fiber in barley is digested by colonic bacteria to produce short-chain fatty acids, which may promote bowel health35 and accelerate repair of colonic mucosa in those with ulcerative colitis.35
Like other fiber-rich foods, barley is associated with weight control.Some trials have suggested that greater dietary fiber consumption increases satiety and decreases caloric intake.36-38 A diet high in protein and fiber—both found in barley—has been shown to minimize overall daily calorie ingestion.39,40
Black Beans Also Target Blood Sugar!
Epidemiological studies showed a strong association between increased consumption of the common bean (Phaseolus vulgaris)—which includes black beans, pintos, and others—and a reduced risk of chronic diseases, including type II diabetes.41-44
In 2012, this was confirmed in two separate, randomized trials in which beans were demonstrated to significantly lower glycemic response in type II diabetics.16,45
Scientists believe that the compounds in beans may slow activity of the alpha-amylase enzymes that help break down starch into sugar. This would reduce or slow sugar release.
Also, beans have a low GI (glycemic index), which by definition means they produce a relatively low rise in blood glucose after a meal46-48—compared to high-glycemic index items such as white rice, which sharply elevate postprandial glucose and increase oxidative stress.49-51
The glucose-lowering effects of beans consumed alone has been well documented, although at least one study had measured this effect when beans were eaten as part of a meal.16,41,48,52 However, a large study recently published in the British Journal of Nutrition found that beans significantly reduce glycemic response even when combined with other—even higher glycemic index—foods.41
Also, a review and meta-analysis that examined 41 studies found that bean consumption—alone, or as part of a low-glycemic index or a high-fiber diet— improves markers of longer-term glycemic control in humans.46
Specifically, this review found that beans produced improvements in HbA1c (glycated hemoglobin) and fructosamine (glycated serum protein).46 Both are markers for longer-term plasma glucose concentration. These observed improvements indicate that beans deliver significant diabetic control over a prolonged period.46
These findings clearly demonstrate that aging individuals—both those with, and those at risk for, type II diabetes—can restore glycemic control with simple diet changes that increase intake of black beans and barley.
Black Beans Help Prevent Devastating DNA Damage
A study was designed to evaluate the toxicogenic (toxin-producing) versus protective effect of cooked and dehydrated black beans on bone marrow and peripheral blood cells of mice.
Remarkably, these scientists found that black beans significantly reduced the frequency of genetic damage induced by chemical mutagens in these types of cells!53
Although not originally part of the study, they also observed that black beans afforded leukocytes the same protection against induced DNA damage.53
Beans Lower Cardiovascular Disease Risk Factors
Research has shown that beans lower cholesterol.44,54-56 This effect is largely attributed to their high soluble-fiber content—a benefit also associated with other soluble-fiber-rich foods.
But beans deliver other cardiovascular effects that flow from their capacity to affect blood sugar.
Both elevated after-meal glucose and chronic hyperglycemia can increase oxidative stress, worsen endothelium-dependent vasodilation, and raise blood pressure—all serious factors in cardiovascular disease.50,57-59 However, by controlling after-meal glucose responses and promoting prolonged diabetic control, beans may help prevent these glucose-related cardiovascular risk factors.16,28,46
In fact, research has now confirmed that low glycemic index foods such as beans are associated with a lower risk for cardiovascular disease, even after accounting for known risk factors such as smoking, diabetes, obesity, and family history of heart disease.43-45,60
A High-Bean Diet Improves Biomarkers for Cancer Risk
Scientists have identified mechanisms by which increased insulin response raises cancer risk.61,62
Studies have found that higher bean intake, by reducing insulin, inflammatory markers, and altering cell signaling pathways, is associated with reduced cancer risk.63-65
Beans May Inhibit Obesity
Beyond evidence of decreased calorie ingestion with increased fiber diets,36-40 observational and controlled studies indicate that consumption of beans improves short-term satiety and weight loss, when combined with energy restriction.66,67
Black Beans Promote Healthy Gastrointestinal Function
The indigestible fraction—which is a measure of the level of indigestibility of a food—in black beans has been shown to be greater than the indigestible fraction in some other beans such as lentils and chickpeas.68 In fact, the indigestible fraction of black beans provides colonic bacteria with the perfect mixture of compounds to generate butyric acid, which is used by colon-lining cells called colonocytes to fuel their activity and keep the lower digestive tract functioning smoothly. It affects cellular proliferation, differentiation and apoptosis (programmed cell death), and has anti-inflammatory effects.69
Evidence strongly indicates that barley and black beans provide superior food options to help reduce blood sugar levels and offer protection from oxidative stress and chronic diseases. They can be substituted for unhealthy foods that have become so prevalent in Western diets.
If you have any questions on the scientific content of this article, please call a Life Extension® Health Advisor at 1-866-864-3027.
- Laukkanen JA, Mäkikallio TH, Ronkainen K, Karppi J, Kurl S. Impaired fasting plasma glucose and type 2 diabetes are related to the risk of out-of-hospital sudden cardiac death and all-cause mortality. Diabetes Care. 2012 Dec 17. [Epub ahead of print]
- Capaldo B, Di Bonito P, Iaccarino M, et al. Cardiovascular characteristics in subjects with increasing levels of abnormal glucose regulation: The Strong Heart Study. Diabetes Care. 2012 Dec 5. [Epub ahead of print]
- Lindkvist B, Almquist M, Bjørge T, et al. Prospective cohort study of metabolic risk factors and gastric adenocarcinoma risk in the Metabolic Syndrome and Cancer Project (Me-Can). Cancer Causes Control. 2013 Jan;24(1):107-16.
- Hirakawa Y, Ninomiya T, Mukai N, et al. Association between glucose tolerance level and cancer death in a general Japanese population: the hisayama study. Am J Epidemiol. 2012 Nov 15;176(10):856-64.
- Savill P. Identifying patients at risk of type 2 diabetes. Practitioner. 2012 Jul-Aug;256(1753):25-7, 3.
- Kandeil MA, Amin KA, Hassanin KA, Ali KM, Mohammed ET. Role of lipoic acid on insulin resistance and leptin in experimentally diabetic rats. J Diabetes Complications. 2011 Jan-Feb;25(1):31-8.
- Medjakovic S, Jungbauer A. Pomegranate: a fruit that ameliorates metabolic syndrome. Food Funct. 2013 Jan 19;4(1):19-39.
- Qin B, Nagasaki M, Ren M, Bajotto G, Oshida Y, Sato Y. Cinnamon extract prevents the insulin resistance induced by a high-fructose diet. Horm Metab Res. 2004 Feb;36(2):119-25.
- Villareal DT, Holloszy JO. Effect of DHEA on abdominal fat and insulin action in elderly women and men: a randomized controlled trial. JAMA. 2004 Nov 10;292(18):2243-8.
- Maneschi E, Morelli A, Filippi S, et al. v Testosterone treatment improves metabolic syndrome-induced adipose tissue derangements. J Endocrinol. 2012 Dec;215(3):347-362. Epub 2012 Oct 8.
- Bayrak A, Terbell H, Urwitz-Lane R, Mor E, Stanczyk FZ, Paulson RJ. Acute effects of metformin therapy include improvement of insulin resistance and ovarian morphology. Fertil Steril. 2007 Apr;87(4):870-5. Epub 2007 Jan 16.
- Basturk T, Unsal A, Ulas T, et al. Effects of rosiglitazone treatment on insulin resistance and TNF-alpha levels in patients with chronic kidney disease: a prospective study. Eur Rev Med Pharmacol Sci. 2012 Nov;16(11):1519-24.
- Roopchand DE, Kuhn P, Rojo LE, Lila MA, Raskin I. Blueberry polyphenol-enriched soybean flour reduces hyperglycemia, body weight gain and serum cholesterol in mice. Pharmacol Res. 2012 Dec 4;68(1):59-67.
- Taniguchi A, Yamanaka-Okumura H, Nishida Y, Yamamoto H, Taketani Y, Takeda E. Natto and viscous vegetables in a Japanese style meal suppress postprandial glucose and insulin responses. Asia Pac J Clin Nutr. 2008;17(4):663-8.
- Behall KM, Scholfield DJ, Hallfrisch J. Comparison of hormone and glucose responses of overweight women to barley and oats. J Am Coll Nutr. 2005 Jun;24(3):182-8.
- Thompson SV, Winham DM, Hutchins AM. Bean and rice meals reduce postprandial glycemic response in adults with type 2 diabetes: a cross-over study. Nutr J. 2012;11:23.
- Wylie-Rosett J, Segal-Isaacson CJ, Segal-Isaacson A. Carbohydrates and increases in obesity: Does the type of carbohydrate make a difference? Obesity Research. 2004 Nov;12(S):124S-9S.
- Available at: http://diabetes.niddk.nih.gov/DM/PUBS/statistics/#youngpeople. Accessed December 1, 2012.
- Available at: http://barleyworld.org/sites/default/files/what_barley_foods_can_do_you.pdf. Accessed December 28, 2012.
- Weickert MO, Pfeiffer AFH. Metabolic effects of dietary fiber consumption and prevention of diabetes. J Nutr. 2008 Mar;138(3):439-42.
- Nilsson A, Granfeldt Y, Ostman E, Preston T, Björck I. Effects of GI and content of indigestible carbohydrates of cereal-based evening meals on glucose tolerance at a subsequent standardised breakfast. Eur J Clin Nutr. 2006 Sep;60(9):1092-9.
- 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 May;59(5):1075-82.
- Anderson JW, Baird P, Davis RH, et al. Health benefits of dietary fiber. Nutr Rev. 2009;67(4):188-205.
- 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.
- Casiraghi MC, Garsetti M, Testolin G, Brighenti F. Post-prandial responses to cereal products enriched with barley beta-glucan. J Am Coll Nutr. 2006;25(4):313-20.
- Keogh JB, Lau CW, Noakes M, Bowen J, Clifton PM. Effects of meals with high soluble fibre, high amylose barley variant on glucose, insulin, satiety and thermic effect of food in healthy lean women. Eur J Clin Nutr. 2007;61(5):597-604.
- Kim H, Stote KS, Behall KM, Spears K, Vinyard B, Conway JM. Glucose and insulin responses to whole grain breakfasts varying in soluble fiber, beta-glucan: a dose response study in obese women with increased risk for insulin resistance. Eur J Nutr. 2009;48(3):170-5.
- Bays H, Frestedt JL, Bell M. Reduced viscosity Barley beta-glucan versus placebo: a randomized controlled trial of the effects on insulin sensitivity for individuals at risk for diabetes mellitus. Nutr Metab (Lond). 2011;8:58.
- Pedersen JI. Peroxisomal oxidation of the steroid side chain in bile acid formation. Biochimie. 1993;75(3-4):159-65.
- Behall KM, Hallfrisch JG. Effects of barley consumption in CVD risk factors. Cereal Food World. 2006;51:12-5.
- AbuMweis SS, Jew S, Ames NP. β-glucan from barley and its lipid-lowering capacity: a meta-analysis of randomized, controlled trials. Eur J Clin Nutr. 2010 Dec;64(12):1472-80
- Keenan JM, Goulson M, Shamliyan T, et al. The effects of concentrated barley beta-glucan on blood lipids in a population of hypercholesterolaemic men and women. Br J Nutr. 2007 Jun;97(6):1162-8.
- Hallfrisch JG, Scholfield DJ, Behall KM. Blood pressure reduced by whole grain diet containing barley or whole wheat and brown rice in moderately hypercholesterolemic men. Nutr Res. 2003;23:1631-42.
- Chutkan R, Fahey G, Wright WL, McRorie J. Viscous versus nonviscous soluble fiber supplements: mechanisms and evidence for fiber-specific health benefits. J Am Acad Nurse Pract. 2012 Aug;24(8):476-87.
- Kanauchi O, Iwanaga T, Andoh A, et al. Dietary fiber fraction of germinated barley foodstuff attenuated mucosal damage and diarrhea, and accelerated the repair of the colonic mucosa in an experimental colitis. J Gastroenterol Hepatol. 2001 Feb;16(2):160-8.
- Schroeder N, Gallaher DD, Arndt EA, Marquart L. Influence of whole grain barley, whole grain wheat, and refined rice-based foods on short-term satiety and energy intake. Appetite. 2009 Dec;53(3):363-9.
- Vitaglione P, Lumaga RB, Stanzione A, Scalfi L, Fogliano V. beta-Glucan-enriched bread reduces energy intake and modifies plasma ghrelin and peptide YY concentrations in the short term. Appetite. 2009 Dec;53(3):338-44. doi: 10.1016/j.appet.2009.07.013. Epub 2009 Jul 23.
- Vitaglione P, Lumaga RB, Montagnese C, Messia MC, Marconi E, Scalfi L. Satiating effects of a barley beta-glucan-enriched snack. J Am Coll Nutr. 2010;29(2):113-21.
- Samra RA, Anderson GH. Insoluble cereal fiber reduces appetite and short-term food intake and glycemic response to food consumed 75 min later by healthy men. Am J Clin Nutr. 2007 Oct;86(4):972-9.
- Weigle DS, Breen PA, Matthys CC, et al. A high-protein diet induces sustained reductions in appetite, ad libitum caloric intake, and body weight despite compensatory changes in diurnal plasma leptin and ghrelin concentrations. Am J Clin Nutr. 2005 Jul;82(1):41-8.
- Hutchins AM, Winham DM, Thompson SV. Phaseolus beans: impact on glycaemic response and chronic disease risk in human subjects. Br J Nutr. 2012 Aug;108 Suppl 1:S52-65.
- Darmadi-Blackberry I, Wahlqvist ML, Kouris-Blazos A, et al. Legumes: the most important dietary predictor of survival in older people of different ethnicities. Asia Pac J Clin Nutr. 2004;13(2):217-20.
- Bazzano LA, He J, Ogden LG, et al. Legume consumption and risk of coronary heart disease in US men and women. Arch Intern Med. 2001;161:2573-8.
- Zhu Z, Jiang W, Thompson HJ. Edible dry bean consumption (Phaseolus vulgaris L.) modulates cardiovascular risk factors and diet-induced obesity in rats and mice. Br J Nutr. 2012 Aug;108 Suppl 1:S66-73.
- Jenkins DJ, Kendall CW, Augustin LS, et al. Effect of legumes as part of a low glycemic index diet on glycemic control and cardiovascular risk facts in type 2 diabetes mellitus: A randomized controlled trial. Arch Intern Med. 2012 Oct 22:1-8.
- Sievenpiper JL, Kendall CW, Esfahani A, et al. Effect of non-oil-seed pulses on glycaemic control: a systematic review and meta-analysis of randomised controlled experimental trials in people with and without diabetes. Diabetologia. 2009;52:1479-95.
- Brand-Miller J, Hayne S, Petocz P, Colagiuri S. Low-glycemic index diets in the management of diabetes: a meta-analysis of randomized controlled trials. Diabetes Care. 2003;26:2261-7.
- Bornet FRJ, Costagliola D, Rizkalla SW, et al. Insulinemic and glycemic indexes of six starch-rich foods taken alone and in a mixed meal by type 2 diabetics. Am J Clin Nutr. 1987;45:588-95.
- Atkinson FS, Foster-Powell K, Brand-Miller JC. International tables of glycemic index and glycemic load values: 2008. Diabetes Care. 2008;31:2281-3.
- O’Keefe JH, Bell DSH. Postprandial hyperglycemia/hyperlipidemia (postprandial dysmetabolism) is a cardiovascular risk factor. Am J Cardiol. 2007;100:899-904.
- Lavi T, Karasik A, Koren-Morag N, et al. The acute effect of various glycemic index dietary carbohydrates on endothelial function in nondiabetic overweight and obese subjects. J Am Coll Cardiol. 2009;53:2283-7.
- Olmedilla-Alonso B, Pedrosa MM, Cuadrado C, Brito M, Asensio-S-Manzanera C, Asensio-Vegas C. Composition of two Spanish common dry beans (Phaseolus vulgaris), ‘Almonga’ and ‘Curruquilla’, and their postprandial effect in type 2 diabetics. J Sci Food Agric. 2012 Aug 30. doi: 10.1002/jsfa.5852. [Epub ahead of print]
- Azevedo L, Gomes JC, Stringheta PC, et al. Black bean (Phaseolus vulgaris L.) as a protective agent against DNA damage in mice. Food Chem Toxicol. 2003 Dec;41(12):1671-6.
- Winham DM, Hutchins AM. Baked bean consumption reduces total cholesterol in mildly hypercholesterolemic men and women. Nutr Res. 2007;27:380-6.
- Winham DM, Hutchins AM, Johnston CS. Pinto bean consumption reduces biomarkers for heart disease risk. J Am Coll Nutr. 2007;26:243-9.
- Anderson JW, Gustafson NJ, Spencer DB, et al. Serum lipid response of hypercholesterolemic men to single and divided doses of canned beans. Am J Clin Nutr. 1990;51:1013-9.
- Davignon J, Ganz P. Role of endothelial dysfunction in atherosclerosis. Circulation. 2004;109:III-27-32.
- Hu Y, Block G, Norkus EP, et al. Relations of glycemic index and glycemic load with plasma oxidative stress markers. Am J Clin Nutr. 2006;84:70-6.
- Ceriello A, Esposito K, Piconi L, et al. Glucose “peak” and glucose “spike”: impact on endothelial function and oxidative stress. Diabetes Res Clin Pract. 2008;82:262-7.
- Hu FB, Rimm EB, Stampfer MJ, et al. Prospective study of major dietary patterns and risk of coronary heart disease in men. Am J Clin Nutr. 2000;72:912-21.
- Stoll BA. Western nutrition and the insulin resistance syndrome: a link to breast cancer. Eur J Clin Nutr.1999;53:83-7.
- Kaaks R. Nutrition, hormones, and breast cancer: is insulin the missing link? Cancer Cause Control. 1996;7:605-25.
- Thompson MD, Mensack MM, Jiang W, et al. Cell signaling pathways associated with a reduction in mammary cancer burden by dietary common bean (Phaseolus vulgaris L.). Carcinogenesis. 2012 Jan;33(1):226-32.
- Thompson MD, Thompson HJ. Physiological effects of bean (Phaseolus vulgaris L.) consumption on cellular signaling in cancer. Cell Cycle. 2012 Mar 1;11(5):835-6.
- Potischman N, Swanson CA, Coates RJ, et al. Intake of food groups and associated micronutrients in relation to risk of early-stage breast cancer. Int J Cancer. 1999;82:315-21.
- McCrory MA, Hamaker BR, Lovejoy JC, et al. (2010) Pulse consumption, satiety, and weight management. Adv Nutr. 2010;1:17-30.
- Leathwood P, Pollet P. Effects of slow release carbohydrates in the form of bean flakes on the evolution of hunger and satiety in man. Appetite. 1988 Feb;10(1):1-11.
- Hernandez-Salazar M, Osorio-Diaz P, Loarca-Piña G, Reynoso-Camacho R, Tovar J, Bello-Pérez LA. In vitro fermentability and antioxidant capacity of the indigestible fraction of cooked black beans (Phaseolus vulgaris L.), lentils (Lens culinaris L.) and chickpeas (Cicer arietinum L.). J Sci Food Agric. 2010 Jul;90(9):1417-22.
- Immerseel FV, Ducatelle R, De Vos M, et al. Butyric acid-producing anaerobic bacteria as a novel probiotic treatment approach for inflammatory bowel disease. J Med Microbiol. 2010 Feb;59(Pt 2):141-3.