Beans and Heart Disease

Andrea M. Hutchins, Ph.D., RD

Dr. Hutchins is an Associate Professor of Nutrition at the University of Colorado at Colorado Springs and is a member of the Bean Institute Editorial Board.  She can be reached at ahutchin@uccs.edu

Legumes or dry beans have been shown to improve serum lipid profiles in patients with coronary heart disease (CHD) 1, 2 and a growing body of evidence supports the positive effects dietary legume consumption confers on health, particularly in relation to risk for CHD.

The current recommendations from the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III) include the use of functional foods such as legumes, oats, and margarines containing plant stanols/sterols in the Therapeutic Lifestyles Diet recommendations 3. The NCEP Adult Treatment Panel III (ATP III) guidelines identify legumes as a good low saturated fat protein source and also recognize their contribution to viscous fiber intake in the diet. One-half cup of legumes supplies 5.5 – 8 grams of total fiber including 1 – 3.5 grams of viscous fiber or 10-35% of the 5 – 10 grams of daily viscous fiber intake recommended by the NCEP ATP III.

Research
Epidemiologic studies support the cardioprotective effects of legumes as part of a healthy diet. In particular, one study examined the relationship between bean consumption and occurrence of cardiovascular disease (CVD) and reported that 1 serving per day of beans was associated with a 38% lower risk of myocardial infarction 4. A second study 5 reported that individuals consuming legumes at least 4 times per week had a 22% lower risk of heart disease than individuals consuming legumes less than once per week.

The number of randomized, crossover research studies that have examined the effects of legumes on cholesterol concentrations is increasing. Many of the initial trails included legumes as only one part of a high-plant, low-cholesterol-type diet. However, more recent studies have focused on the hypocholesterolemic effects of legumes as part of a controlled or normal diet. Overall, data from these studies indicate that consumption of canned or cooked beans 6-18 will lower total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) levels.

The amount of legumes used in these studies has generally ranged from ½ cup to 1 cup per day, which fits within the NCEP ATP III guidelines. Reductions in TC and LDL-C have varied from 5-8% in the studies that had participants consume ½ cup of legumes 9, 17 to 19-24% when 1 cup was consumed 10, 18.

Several possible mechanisms of action exist which may explain the hypocholesterolemic effects of legumes. These mechanisms include fat displacement from the diet, direct binding of dietary cholesterol by viscous fiber in the intestine, interruption of bile acid enterohepatic circulation, and inhibition of endogenous cholesterol synthesis by short chain fatty acids (SCFA). However, it has yet to be determined which mechanism or combination of mechanisms is responsible for the hypocholesteremic effects of legumes.

Take Home Message
Overall, research studies support the hypocholesterolemic effects of legumes. Reductions in blood cholesterol due to consuming beans may be considered modest by the medical community (typically in the 6 – 10% range). However, due to the fact that many legume types are inexpensive, readily available and widely accepted among the US population, implementation of dietary changes that include increased legume consumption to improve risk for CHD appears realistic in comparison to other, more traditional interventions, namely conventional drug therapy. Although it cannot be argued that some individuals, particularly those with excessively elevated serum lipoprotein profiles and genetic predisposal to lipid abnormalities, require the help of medications such as statins, to achieve normal, healthy serum lipoprotein profiles, this type of therapy does not appear to be optimal for everyone due to safety concerns and cost constraints 3. Therefore, individuals who do not require the use of such medications should be encouraged to make reasonable diet and physical activity behavior change modifications that are generally safer, offer fewer side effects, are more affordable and provide more widespread health benefits. Additionally, eating beans may provide protection from CVD beyond what can be explained by a small depression in blood cholesterol 4. It is possible that the wide variety of phytochemicals in beans provide protection against developing CVD and studies are beginning to explore these additional protective properties. Thus, it is essential that the current recommendations established by governmental agencies for increased, frequent legume consumption be conveyed to the public, who can use this simple dietary modification to improve their health.

References
1.    Anderson JW, Major AW. Pulses and lipaemia, short- and long-term effect: Potential in the prevention of cardiovascular disease. Br J Nutr. 2002;88(Suppl 3):S263-S271.
2.    Bazzano LA, Thompson AM, Tees MT, Nguyen CH, Winham DM. Non-soy legume consumption lowers cholesterol levels: a meta-analysis of randomized controlled trials. Nutr Metab Cardiovasc Dis. 2009;epub ahead of print doi:10.1016/j.numecd.2009.08.012.
3.    National Cholesterol Education Program Expert Panel on Detection E, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III),. Third Report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III), Final Report. Washington, D.C.: National Heart, Lung and Blood Institute of the National Institutes of Health; September 2002. NIH Publication No. 02-5215.
4.    Kabagambe EK, Baylin A, Ruiz-Narvarez E, Siles X, Campos H. Decreased consumption of dried mature beans is positively associated with urbanization and nonfatal acute myocardial infarction. J Nutr. 2005;135(7):1770-1775.
5.    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(21):2573-2578.
6.    Anderson JW, Ratliff P. High-carbohydrate, high-fiber diets decrease insulin requirements of type-1 diabetic individuals. Clin Res. 1987;35(6):A898-A898.
7.    Anderson JW, Smith BM, Washnock CS. Cardiovascular and renal benefits of dry bean and soybean intake. Am J Clin Nutr. 1999;70(3):464S-474S.
8.    Shutler SM, Bircher GM, Tredger JA, Morgan LM, Walker AF, Low AG. The effect of daily baked bean (Phaseolus vulgaris) consumption on the plasma lipid levles of young, normo-cholesterolemic men. Br J Nutr. 1989;61:257-265.
9.    Winham DM, Hutchins AM, Johnston CJ. Pinto bean consumption reduces biomarkers for heart disease risk. J Am Coll Nutr. 2007;26(3):243-249.
10.    Anderson JW, Gustafson NJ, Spencer DB, Tietyen J, Bryant CA. Serum lipid response of hypercholesterolemic men to single and divided doses of canned beans. Am J Clin Nutr. 1990;51:1013-1019.
11.    Bingwen L, Zhaofeng W, Wanzhen L, Rongjue Z. Effects of bean meal on serum cholesterol and triglycerides. Chinese Med J. 1981;94:455-458.
12.    Finley JW, Burrell JB, Reeves PG. Pinto bean consumption changes SCFA profiles in fecal fermentations, bacterial populations of the lower bowel, and lipid profiles in blood of humans. J Nutr. 2007;137(11):2391-2398.
13.    Jenkins DJA, Wolever TMS, Jenkins AL, et al. The glycemic index of foods tested in diabetic-patients – a new basis for carbohydrate exchange favoring the use of legumes. Diabetologia. 1983;24(4):257-264.
14.    Jimenez-Cruz A, Turnbull WH, Bacardi-Gascon M, Rosales-Garay P. A high-fiber, moderate-glycemic-index, Mexican style diet improves dyslipidemia in individuals with type 2 diabetes. Nutr Res. 2004;24(1):19-27.
15.    Simpson HCR, Lousley S, Geekie M, et al. A high-carbohydrate leguminous fiber diet improves all aspects of diabetic control. Lancet. 1981;1(8210):1-4.
16.    Winham DM, Hutchins AM. Baked bean consumption reduces total cholesterol in mildly hypercholesterolemic men and women. Nutr Res. 2007;27:380-386.
17.    Jenkins DJ, Wong GS, Patten R, et al. Leguminous seeds in the dietary management of hyperlipidemia. Am J Clin Nutr. 1983;38:567-573.
18.    Anderson JW, Story L, Sieling B, Chen W-JL, Petro MS, Story J. Hypocholesterolemic effects of oat-bran or bean intake for hypercholesterolemic men. Am J Clin Nutr. 1984;40:1146-1155.