5 Surprising Facts about Beans

image of an assortment of beans on black wooden background. Soybean, red kidney bean, black bean,white bean, red bean and brown pinto beans

No doubt about it, beans are a nutritionally dense food and an inexpensive one as well. All varieties of beans are a good source of protein and complex carbohydrates. Plus, they’re rich in vitamins and minerals. Despite sporting a stellar nutritional profile, most people don’t eat a lot of beans or lentils. The average person eats a serving or two a week when they pop into Taco Bell for a bean burrito but rarely eat them otherwise. As might expect, vegetarians nosh on more legumes than non-vegetarians as beans or lentils are often a plant protein-based substitute for meat. But, omnivores and vegetarians alike could benefit from eating more of these nutrient-dense orbs. Here are five things you might not know about beans.

Uncooked Kidney Beans Are Toxic

Kidney beans, like other beans, are packed with nutrients and phytonutrients. However, uncooked kidney beans, including white (cannelloni) beans contain high levels of compounds called phytohemagglutinins. These so-called “anti-nutrients” fall under a class of compounds called lectins. Lectins modestly reduce the absorption of some minerals when you eat foods that contain them.

Although all legumes contain some phytohemagglutinins, kidney beans contain the most. That’s important since the phytohemagglutinins in kidney beans are toxic. In fact, eating as little as four or five raw kidney beans can cause severe vomiting and diarrhea. There are even reports of death due to dehydration related to ingesting phytohemagglutinins from kidney beans.

The good news is you can greatly reduce the number of phytohemagglutinins in kidney beans by soaking them for five or more hours and then boiling them for at least 30 minutes when you prepare them. What you don’t want to do is pop them into a slow cooker. The temperature doesn’t get high enough to destroy the phytohemagglutinins in kidney beans.

Beans Are a Rich Source of Antioxidants

We think of colorful fruits and vegetables as powerhouse sources of antioxidants – but beans have more antioxidants than many common veggies we put on our plates. In fact, a study found that small red beans are a better source of antioxidants than even wild blueberries, one of the most antioxidant-rich foods on the produce stand. In general, beans that are darker in color, dark red or black, are the most antioxidant-rich. White beans generally contain the fewest antioxidants. So, choose your beans carefully and you’ll power up the antioxidant content of your diet.

They’re a Weight Loss Food

Contrary to what the ads tell you, there are no “magical” foods that will melt the pounds away without effort. Controlling your weight is about the totality of your diet. However, adding a serving or two of beans to your plate might make it easier to control your weight. How do we know? A systematic review of a number of studies found that eating one serving of beans or lentils daily (about ¾ of a cup) was linked with weight loss of just over half a pound. Why might this be? The research shows that eating beans boosts feelings of satiety by 31%. That’s not surprising since beans are a good source of fiber, to slow digestion, and plant protein, a macronutrient that boosts satiety.

Eating Beans May Help the Environment

A group of scientists from Oregon State University Loma Linda University, and Bard College made some calculations on the impact substituting beans for beef would have on the environment. According to their math, if all Americans made this substitution, the United States would hypothetically almost meet its 2020 greenhouse gas-emission goals. The study also found that raising cattle for beef is an inefficient use of farmland. Switching from beef to beans would free up to 42% of the cropland in the United States. So, beans aren’t just nutritionally dense and waistline friendly, they’re good for the environment as well.

Beans Are Blood Sugar Friendly

Thanks to their high fiber content, beans are slowly absorbed from the intestinal tract. Due to their slow absorption, they cause a less pronounced rise in blood glucose relative to meals that contain starches. In one study, researchers found adding beans to rice reduced the glucose respond relative to consuming rice alone. In fact, beans are a good addition to the diet of diabetics and pre-diabetics. A study published in the Archives of Internal Medicine found that consuming a daily serving of beans or lentils was linked with a modest drop in blood sugar. Plus, in the study, participants also enjoyed modest reductions in blood pressure and cholesterol. That’s why the American Diabetes Association recommends that diabetics add a few servings of legumes to their plates weekly.

The Bottom Line

If you’re not eating beans, why not? If you buy bulk beans from a bin, they’re one of the least expensive sources of protein. Plus, beans are versatile. You can use them to make plant-based burgers, as a side dish, add them to soups and salads. Some people even use black beans to make a healthier version of a chocolate brownie. Look for recipes online! Don’t forget about lentils and split peas. They have many of the same health benefits as beans. So, enjoy beans! Be sure to vary the type you eat for more nutritional diversity. You’ll find lots to choose from.



J. Agric. Food Chem., 1974, 22 (1), pp 17–22.
Encyclopedia of Food Sciences and Nutrition (Second Edition), 2003. “Plant Anti-Nutritional Factors”
Precision Nutrition. “All about Lectins”
WebMD. “Antioxidant Riches Found in Unexpected Foods”
Foodborne Pathogenic Microorganisms and Natural Toxins Handbook: Phytohaemagglutinin. Food and Drug Administration. 2012. “Consumers should boil the beans for at least 30 minutes to ensure that the product reaches sufficient temperature”
Nutraingredients.com. “Black Beans High in Antioxidant Ratings”
Science Daily. “Eating beans, peas, chickpeas or lentils may help lose weight and keep it off”
American Journal of Clinical Nutrition, March 2016 DOI: 10.3945/ajcn.115.124677.
The Atlantic. “If Everyone Ate Beans Instead of Beef”
FASEB Journal. Vol. 31, No. 1_supplement. April 2017.
Nutr J. 2012; 11: 23.
Reuters. “Beans show promise with diabetes: study”
American Diabetes Association. “Grains and Starchy Vegetables”


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