We all know the silly rhymes about beans, how they’re good for your heart but lead to certain gastrointestinal symptoms that children (and some adults) find funny. And it’s true, beans are great for your heart: just one serving (½ cup) per day lowers your risk of experiencing a heart attack by 38%[i]! And beans don’t stop there; they also protect you from cancer, diabetes, obesity, and ulcerative colitis! So let’s look at this powerful food a little more closely!
Why is it that we can confidently say that eating beans regularly increases your cardiovascular health and decreases your risk of premature death? One reason is that beans increase fat burning and weight loss. This is due partly to their fiber and resistant startch content (more on that below), and also to the amount of arginine and glutamine that they supply. Not only do beans help your heart by increasing weight loss and lowering cholesterol, there is good evidence that eating 1 cup of beans per day for three months will slow your heart rate as effectively as exercise[ii]! Why is this important? Because for every 10 beat-per-minute increase in resting heart rate above 60 beats-per-minute, your risk of premature death increases 10-20%[iii]!! So eat your beans, decrease your heart rate, cholesterol, and body fat, and increase your lifespan!
If you have diabetes or have ever tried losing weight by counting carbs you might be thinking, “but wait, aren’t beans high in carbohydrates? Shouldn’t I be limiting them?” Not all carbohydrates are created equal. You’ve probably heard that carbohydrates turn into sugar in our bodies and if sugar isn’t immediately used for energy it is stored as fat. That is true for what we call “empty carbohydrates,” the foods that contain carbs and sugar with little fiber and few micronutrients. Beans are a different story. Beans are not only high in micronutrients, the carbohydrate portion of beans contains fiber and something called resistant starch. Fiber is an indigestible portion of plant food that remains in our intestinal tract. Fiber is highly beneficial for digestion. It provides bulk to our stool and keeps it moving through our digestive tract, preventing diverticulosis and diverticulitis. It also binds toxins and cellular waste products, removing them from our bodies. And fiber slows our absorption of fat and sugar, helping to prevent weight gain.
The resistant starch content of beans is what really earns them the gold star. Resistant starch is named so because it resists enzymatic breakdown in the small intestine and travels to the colon to be degraded by your gut bacteria. Food labels are somewhat misleading because they categorize resistant starch under the carbohydrate content. However, 90% of the calories from resistant starch are never absorbed, it just breaks down too slowly! Resistant starch is present in all foods that contain natural carbohydrates, however it is much higher in beans, lentils, split peas, corn and brown rice than in other plant foods.
Still, besides the fact that it doesn’t count towards calories, why should you be particularly excited about resistant starch? Because when the bacteria in your large intestine ferment resistant starch it produces short-chain fatty acids such as butyrate. Butyrate is excellent fuel for your colon cells and has been shown in cell culture to stop the proliferation (growth) of cancer cells and to induce cancer cell death[iv]!! That’s right: beans prevent colon cancer and kill cancer cells that are present. And because butyrate provides quality fuel for intestinal cells, it has been used successfully to treat ulcerative colitis as patients with this condition show decreased butyrate production[v].
Even more impressive, butyrate has been shown to alter the expression of your genes. Studies have shown that eating more beans and producing more butyrate increases the expression of genes that promote cancer cell death, decrease inflammation, and enhance energy metabolism[vi]. In human studies, people that consume ½ cup of beans twice per week have 47% lower risk of colon cancer compared to people who consumed ½ cup of beans less than one time per week[vii]. And those who ate ½ cup of beans more than 4 times per week had 33% lower risk of colon polyp recurrence than those who did not eat beans as frequently[viii].
And the cancer protective effects of beans extend far beyond the colon. Beans also contain a compound called inositol pentakisphosphate, or IP-5, which has been shown to inhibit the growth of ovarian, breast, and lung cancer cells. Not only is IP-5 able to inhibit cancer cell growth, it does so as effectively as the drug cisplatin, a chemotherapeutic agent used to treat a number of cancers[ix].
Wait, we aren’t done yet! Beans also contain phytic acid, also known as inositol hexaphosphate. Phytic acid is quickly absorbed and taken up by cancer cells to inhibit their growth. This has been demonstrated in leukemia, colon cancer, breast cancer (both estrogen receptor-positive and negative), cervical cancer, prostate cancer, liver cancer, pancreatic cancer, melanoma, and muscle cell cancers. The best part is it doesn’t affect healthy cells and its mechanism of action blocks all the principal pathways of malignancy[x]! Additionally, the phytic acid in beans also prevents kidney stones, dental cavities, diabetes, and heart disease!
With all these benefits to eating beans regularly, can you really afford not to?
[i] 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.
[ii] 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 factors in type 2 diabetes mellitus: a randomized controlled trial. Arch Intern Med. 2012;172(21):1653-60.
[iii] Woodward M, Webster R, Murakami Y, et al. The association between resting heart rate, cardiovascular disease and mortality: evidence from 112,680 men and women in 12 cohorts. Eur J Prev Cardiology. 2014;21(6):719-726.
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[v] Scheppach W, Sommer H, Kirchner T, et al. Effect of Butyrate enemas on the colonic mucosa in distal ulcerative colitis. Gastroenterology. 1992 Jul;103(1):51-6.
[vi]Williams EA, Coxhead JM, Mathers JC. Anti-cancer effects of butyrate: use of micro-array technology to investigate mechanisms. Proc Nutr Soc. 2003 Feb;62(1):107-15.
[vii] Singh PN, Fraser GE. Dietary risk factors for colon cancer in a low-risk population. American Journal of Epidemiology. 1998;148(8):761-774.
[viii] Michels KB, Giovannucci E, Chan AT, Singhania R, Fuchs CS, Willett WC. Fruit and vegetable consumption and colorectal adenomas in the nurses’ health study. Cancer Research. 2006;66(7):3942-3953.
[ix] Falasca M. Anti-cancer activity of the bioactive compound inositol pentakisphosphate. Phytochem Rev. 2009 June;8(2): 369-374.
[x] Shamsuddin, AM. Anti-cancer function of phytic acid. Intl J Food Sci Tech. 2002;37:769-782.