Friday Favorites: Benefits of Beans for Peripheral Vascular Disease

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

“Legumes [by which they mean all kinds of beans, chickpeas, split peas, and lentils] are an excellent source of many essential nutrients…vitamins, minerals, fibers, antioxidants…” And, not just an excellent source; perhaps the single cheapest source. In terms of nutrition density per penny, the four that really pull away from the pack are pinto beans, lentils, black beans, and kidney beans.

And, all that nutritional quality may have beneficial effects on excess body weight, insulin resistance, high cholesterol, inflammation, and oxidative stress—all “major cardiovascular risk factors.” So, do men and women who eat more beans tend to have less heart disease? Yes, suggesting that “increasing legume intake may be an important part of a dietary approach to the primary prevention of [coronary heart disease] in the general population”—meaning prevention of heart disease in the first place. But, maybe those eating more bean burritos are just eating fewer beef burritos? They took that into account, controlling for meat intake, fruits and vegetables, and smoking, and exercise. And, still, the bean-eaters appeared to be protected.

Note the highest category was eating legumes four or more times a week. In my Daily Dozen, I recommend people eat legumes three times—a day! In Costa Rica, they were able to find enough people eating beans every day. And, even after controlling for many of the same things, like intake of saturated fat and cholesterol, one bean serving a day was “associated with a 38% reduction in the risk of [heart attack].” Yeah, but do you actually get to live longer, too? Yes, apparently so: an 8% lower all-cause mortality, again after adjusting for other dietary factors. You can’t control for everything, though. You can’t really prove cause-and-effect until you… put it to the test.

Randomized controlled interventional trials have found that “dietary [bean] intake [does] significantly reduce…[bad] cholesterol levels,” dating back a half century to 1962. Measure cholesterol levels at baseline, and then add beans to their diet, and then remove beans from their diets.

And, look, beans have “a low glycemic index and saturated fat content, and are high in fiber, potassium, and plant protein, each of which independently confers BP-lowering effects.” But, “[w]hether there’s sufficient evidence to emphasize [beans] alone to lower BP…is unclear.” Therefore, what we need is “a systematic review and meta-analysis of controlled feeding trials.” And, here it is. And, what they found is that beans do indeed lower blood pressure, no matter where you start out.

Okay, so, beans may be able to prevent artery disease, but what about reversing it? Can the daily consumption of beans—other than soy—reverse vascular impairment due to peripheral artery disease? Peripheral artery disease “results from a decrease in blood flow to the [legs] due to the [buildup of] atherosclerotic plaque” higher up. Yeah, soybeans may help. But what about other beans? So, they had twenty-six individuals with peripheral artery disease consume one serving a day of a combination of beans, split peas, lentils, and chickpeas for eight weeks.

Basically, how you diagnose and follow the disease is with “the ankle-brachial index,” which is just the ratio of blood pressure at your ankle compared to your arm. Once it dips below point nine, that means you must have some kind of clogs in blood flow to your lower body. But, eat some beans, and you may get a significant increase, enough to push four of 26 participants up into the normal range after just eight weeks, eating some beans! Now, there was no control group, but people tend to get worse, not better. The researchers conclude: “A legume-rich diet can elicit major improvements in arterial function.”

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• Drewnowski A, Rehm CD. Vegetable cost metrics show that potatoes and beans provide most nutrients per penny. PLoS ONE. 2013;8(5):e63277.
• Nagura J, Iso H, Watanabe Y, et al. Fruit, vegetable and bean intake and mortality from cardiovascular disease among Japanese men and women: the JACC Study. Br J Nutr. 2009;102(2):285-92.
• Bazzano LA, He J, Ogden LG, et al. Legume consumption and risk of coronary heart disease in US men and women: NHANES I Epidemiologic Follow-up Study. Arch Intern Med. 2001;161(21):2573-8.
• Jayalath VH, De souza RJ, Sievenpiper JL, et al. Effect of dietary pulses on blood pressure: a systematic review and meta-analysis of controlled feeding trials. Am J Hypertens. 2014;27(1):56-64.
• Bouchenak M, Lamri-senhadji M. Nutritional quality of legumes, and their role in cardiometabolic risk prevention: a review. J Med Food. 2013;16(3):185-98.
• Ha V, Sievenpiper JL, De souza RJ, et al. Effect of dietary pulse intake on established therapeutic lipid targets for cardiovascular risk reduction: a systematic review and meta-analysis of randomized controlled trials. CMAJ. 2014;186(8):E252-62.
• Zahradka P, Wright B, Weighell W, et al. Daily non-soy legume consumption reverses vascular impairment due to peripheral artery disease. Atherosclerosis. 2013;230(2):310-4.
• 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):1770-5.
• Luyken R, Pikaar NA, Polman H, Schippers FA. The influence of legumes on the serum cholesterol level. Voeding. 1962;23:447-53.

Image credit: StockSnap via Pixabay. Image has been modified.

Motion graphics by Avocado Video.