Legumes: Health Benefits and Culinary Approaches to Increase Intake

Much evidence supports the health benefits of consuming a plant-based diet and increasing the intake of legumes. A high intake of fruits, vegetables, whole grains, legumes (beans), nuts, and seeds is linked to significantly lower risks of heart disease, high blood pressure, stroke, and type 2 diabetes (1,2). The American Diabetes Association’s nutrition therapy recommendations for the management of adults with type 2 diabetes note that many eating patterns are acceptable for people with diabetes. Several diets, including the DASH (Dietary Approach to Stop Hypertension) and Mediterranean-style plans, although not strictly vegetarian, still promote increased intake of plant-based foods such as legumes and their associated health benefits (3). Although research supports the benefits of legume consumption, only ∼8% of U.S. adults report eating legumes on any given day (4). The purpose of this article is to highlight the research demonstrating the benefits of increasing legumes in the diet and to offer practical suggestions to aid health care providers in increasing their own legume intake and more confidently discussing such a goal with their patients.

Unlike with some other chronic conditions, individuals who have type 2 diabetes are responsible for providing up to 95% of their own care (5). One of the most challenging aspects of type 2 diabetes care is helping patients adopt healthier behaviors. When nutrition therapy is provided by a qualified professional, people can learn how to make better food choices to help improve their glycemic control, blood pressure, cholesterol, and BMI (6). In fact, medical nutrition therapy (MNT), as provided by a registered dietitian, has been shown to improve glycemic control outcomes and reduce health care costs to Medicare (7).

Recent literature demonstrates the benefit of augmenting this nutritional information with skills-based culinary education. Robust correlations exist between healthy food preparation skills and improved dietary quality (8) and between time spent in the kitchen and mortality (9), supporting the importance of preparing meals oneself. However, a 2007–2008 survey evaluating trends in U.S. home food preparation found a decrease in cooking activities (10). In response, it has been recommended that nutrition counseling expand from a primary focus on nutrients to include developing practical culinary skills (e.g., meal planning, shopping, food storage, and food preparation) (11–13). Culinary education was found to improve attitudes regarding healthy cooking (14) and to increase time spent cooking (15), confidence in cooking (16), healthy food consumption (14,15), and health outcomes (17). One program was reported to improve the pattern of nutrient intake in people with type 2 diabetes (18).

Providers, including physicians, dietitians, nurses, and pharmacists, can provide the knowledge and tools to help build skills and facilitate behavior change, but they can further help their patients (and themselves) in another way: by serving as role models for their patients. Individuals with diabetes who receive counseling from providers who value the importance of a healthful diet—and model this behavior by working to improve their own eating behaviors—are more likely to adopt a healthful eating plan (19,20).

Knowledge, skills, and tools aimed at increasing consumption of legumes are provided in the following sections and can help health care providers improve both their own and their patients’ eating habits.

Health Benefits of Legumes

By definition, beans are edible, nutritious seeds in the form of pods within the legume family. There are many varieties of legumes (sometimes called “pulses”). Some common types include kidney beans, cannellini beans, Great Northern beans, navy beans, fava beans, cranberry beans, black beans, pinto beans, soy beans, black-eyed peas, chickpeas, and lentils (21).

Many people are surprised to learn just how nutritious legumes are. They provide fiber, protein, carbohydrate, B vitamins, iron, copper, magnesium, manganese, zinc, and phosphorous. Legumes are naturally low in fat, are practically free of saturated fat, and because they are plant foods, they are cholesterol free as well. One serving of legumes, which is one-half cup, provides about 115 calories, 20 g of carbohydrate, 7–9 g of fiber, 8 g of protein, and 1 g of fat. Legumes also have a low glycemic index, generally ranging between 10 and 40.

Legumes are an integral part of many healthy eating patterns, including the Mediterranean style of eating, the DASH eating plan, vegetarian and vegan diets, and lower-glycemic-index (GI) diets. Along with being a highly nutritious food, evidence shows that legumes can play an important role in the prevention and management of a number of health conditions.

Type 2 Diabetes

A diet rich in plant-based foods, including legumes, and lower in refined grains, sugar-sweetened beverages, and processed meats has been shown to lower the risk of developing type 2 diabetes and, for those who have diabetes, to improve both glycemic and lipid control (22). In one study, 121 subjects with type 2 diabetes were randomized to either a low-GI diet emphasizing legume consumption (target: 1 cup/day of cooked legumes, or ∼190 g) or a diet emphasizing wheat fiber foods. After 3 months, 93.3% completed the low-GI legume diet arm and reported an average intake of 211 g/day. A similar proportion (95.1%) completed the high–wheat fiber diet arm. Mean A1C fell by 0.5% (P <0.001) with the low-GI legume diet with significant decreases in total cholesterol and triglyceride levels, as well as decreases in systolic and diastolic blood pressure compared to the diet high in wheat fiber foods (23). Other studies have also reinforced the positive effects of legumes on reductions in A1C and blood glucose levels (24,25).

Hyperlipidemia

Regularly eating legumes may help lower total and LDL cholesterol levels. A meta-analysis of 10 randomized, controlled trials in which non-soy legumes were consumed for a minimum of 3 weeks revealed that eating legumes has a cholesterol-lowering effect. The mean net change in total cholesterol in the legume-eaters compared to a control group was –11.8 mg/dL (95% CI −16.1 to −7.5), and the mean net change in LDL cholesterol was –8.0 mg/dL (95% CI −11.4 to −4.6) (26). In another trial, 31 subjects with type 2 diabetes followed either a legume-free therapeutic diet for heart disease or the same diet replacing two servings of red meat with legumes on 3 days/week. Researchers saw improvements with the legume group in LDL cholesterol and triglycerides, as well as in fasting blood glucose and insulin levels (27).

Hypertension

Legumes are rich in potassium, magnesium, and fiber, all nutrients that have a positive impact on blood pressure management (28). A systematic review and meta-analysis combined the results of eight trials involving >500 people, half of whom were overweight or obese, and found reductions in blood pressure in those who ate legumes. In subjects who consumed slightly less than 1 cup of legumes each day for 10 weeks, both systolic and mean arterial blood pressure were significantly decreased (29). In another study, 113 obese subjects consumed two servings of legumes and four servings of whole grains per day for 18 months in place of refined carbohydrate foods. Blood pressure, triglycerides, weight, and waist circumference were reduced (30).

Weight Management

A diet that regularly includes legumes may help with weight control. The fiber, protein, and slowly digested carbohydrate found in legumes may aid in satiety. Using data from the National Health and Nutrition Examination Survey (NHANES), it was observed that adults who consumed a variety of legumes had significantly lower body weights compared with those who did not consume legumes. Legumes consumers also were much less likely to be obese (BMI >30 kg/m²) than non-consumers (31). Furthermore, evidence supports the beneficial effect of a Mediterranean-style eating plan, which is rich in legumes, fiber, and monounsaturated fat, for weight loss (32).

Despite the well-documented health benefits of legume consumption, the actual intake of legumes remains low. According to NHANES data, on any given day, only ∼8% of adults consume dry legumes and peas (4). This may be attributed, in part, to people’s unfamiliarity with how to prepare and incorporate them into their eating plan.

Preparing Legumes

There are many myths about alleged difficulties in preparing legumes. Some people imagine long soaking periods, whereas others dread complicated preparation techniques. The truth is that legumes are very easy to use, especially when you know some tips about preparing them.

Lentils

Lentils come in a variety of colors, including orange, green, and black. Not only do many lentils have relatively short cooking times, they do not require advance soaking. Even lentils that are relatively slow to cook require just 20 minutes of cooking time. To prepare lentils, place them in a small pot and add water, with a pinch of salt, to cover. Bring to a boil over high heat, then reduce the heat and simmer, uncovered, for about 20 minutes, until lentils are soft. Drain the lentils and use them as discussed below. To reduce preparation time even more, you can always prepare a double batch of lentils when you do cook them; cooked lentils can be stored in the refrigerator up to 5 days.

Split orange lentils are particularly easy to prepare; rinse them, put them in a pot with cold water and salt (3 cups of water for every cup of lentils), and bring to a boil. When the water boils (3–5 minutes), the lentils are ready. Drain the lentils, rinse them in cold water to stop the cooking process, and then use them in your recipe. Keeping these easy-to-prepare lentils on hand will enable you to use them whenever you like.

The texture of quickly cooked lentils should be a bit crunchy; if you want them softer, cook the orange lentils longer, up to 6–8 minutes. If you cook lentils for a long time, their texture becomes very soft, and they may almost seem pureed. Lentils cooked in this manner can be made into a thick, Indian-style sauce by adding spices such as curry, turmeric, cumin, and garam masala and served over brown rice.

Slow-Cooked Legumes

A few members of the legume family, including chickpeas and kidney beans, need more time to cook. Soak the legumes overnight and drain. Then, in a large pot, combine legumes, water, and 1 tsp. of baking soda (to help soften the legumes more quickly), and bring to a boil over high heat. Reduce heat to medium and cook, uncovered, for about 2 hours, until the legumes are soft. Drain the legumes, season with salt and pepper (with this kind of legume it is preferable to season at the end of the cooking process), and set aside to cool.

Although it takes some time, soaking and cooking the legumes does not take much planning or effort. You can also prepare slow-cooking legumes in advance and store them in the freezer. The next time you prepare slow-cooking legumes such as chickpeas or white beans, prepare a double batch and freeze the portion you are not using immediately in freezer-safe storage bags.

If you would like to start using legumes but are concerned about the preparation time, you can start with using prepared beans, which may be purchased frozen or canned. Most canned beans are high in sodium, so look for lower-sodium varieties, and rinse them before using.

Incorporating Legumes Into Your Meal Plan

Legume Salad

A basic legume salad can be made from a combination of any kind of cooked legumes, together with chopped herbs, lemon juice, olive oil, salt, and pepper. Then, you can add chopped vegetables or fruit, cheese cubes, or even slices of chicken breast. See, for example, the recipe for Orange Lentil Salad With Feta and Fresh Herbs in the box on p. 200. For variety, add walnuts, diced tomato, celery slices, sliced chicken breast, or any combination of these ingredients. You can also replace the orange lentils with cooked green lentils, chickpeas, or white beans.

This salad can be prepared a full day in advance if you leave out the cheese cubes until just before serving. Simply mix the rest of the ingredients and let the salad sit covered in your refrigerator. You can also let it sit at room temperature; some lentils may sprout while the salad is marinating, giving the salad a softer texture and more interesting appearance.

Legumes Soup

Legumes are an excellent soup ingredient. Because soups often require longer cooking times, you may not mind the amount of time required to cook legumes for this purpose. Take your favorite combination of legumes and vegetables, simmer them together for 30–40 minutes, add a few herbs and some lemon juice, and you will have a nice Mediterranean soup. For example, in a large pot, bring 1 cup of red lentils, 6 cups of water, and a pinch of salt to a boil over high heat. Reduce heat to low and cook, uncovered, for 30 minutes, until soft. Periodically remove the foam that forms on top. In the meantime, heat 2 Tbsp. of olive oil in a large frying pan over medium heat. Add 1 cup of chopped celery and 6 crushed garlic cloves, and sauté for 2 minutes until brown. Add about a half bunch of chopped cilantro and 4 peeled turnips cut into 1/2-inch cubes, and cook for 2 minutes. Add turnip mixture to lentils and cook for 20 minutes. Mix in 3 Tbsp. of lemon juice and cook for an additional 3 minutes. Add salt and pepper to taste and serve.

Another way to make legume soup is by cooking the legumes with aromatic ingredients such as onion, garlic, or leeks until soft. Then transfer everything to a food processor or use an immersion blender and puree until smooth. You can also add your favorite legumes to any soup you prepare regularly.

Legumes as a Whole Vegetarian Meal

All legumes, when served with a grain, contain all the essential amino acids and are recommended as protein choices, especially for vegetarians or vegans. For example, the famous Mediterranean dish majadra traditionally combines rice and green lentils and can be made easily from leftovers as in the recipe for Aromatic Mixed Rice and Lentils in the box on p. 201.

This recipe is very adaptable. Replace the green lentils with black lentils or mung beans, or replace the brown rice with wheat berries. Adding vegetables to this recipe is an excellent way to improve the nutritional value and enhance the flavor. Sauté 1 cup sliced button mushrooms in 2 Tbsp. of unrefined canola oil and spoon over the rice and lentil mixture just before serving.

Adding Legumes to Everyday Cooking

Having a supply of cooked legumes in your refrigerator or freezer will enable you to add them to almost any dish you make. For example, add 1 Tbsp. of prepared lentils to every cup of prepared rice or quinoa to enrich the color and texture of these grains. Try adding legumes to your beef stew or fish as in the recipe for Sea Bass With Vegetable and Chickpeas in the box on p. 202. If you want to vary the recipe, replace the chickpeas with black or white beans or with any other legume whose color goes well with the other ingredients. Any kind of legume can be added to a variety of salads as well. The next time you make a green salad, toss in a bunch of legumes to add protein and fiber and enhance the color, texture, and taste.

Upgrading Your Legume Recipes

A squeeze of lemon juice will probably enhance the flavor of any legume dish, whether warm, like soup or legume stew, or cold, like salad. Yogurt might also be just what a legume dish needs to make its flavor complete. Serve legume soups with a small bowl of yogurt or the majadra topped with 3 Tbsp. of plain yogurt. It usually takes time for legumes to absorb some of the flavors. If you are not satisfied with the result immediately, taste it again before serving.

Making Legume Sprouts

The nutritional benefit of including legume sprouts in one’s eating plan is that they are low in calories and carbohydrate. For example, 1 cup of raw mung bean sprouts (which shrinks to 1/2 cup cooked bean sprouts) contains just 31 calories and 6 g of carbohydrate, along with 2 g of fiber and 3 g of protein. Mung bean sprouts also provide vitamin C, vitamin K, and folate.

The culinary benefit of including legume sprouts is that they do not need to be cooked. All you need to make sprouts are legumes and some room in your pantry. Every type of raw legume can sprout as long as it is in its natural form and has not been cut or split. The process is simple: let the legumes soak for 10–24 hours, and then spread them in a layer on a large plate, tray, or colander. Make sure the layer is no more than a couple of legumes thick. Cover the legumes with a damp kitchen towel or with plastic wrap that is pierced in a few spots with a fork, and place them in a dark place. The seed sprouts are ready to eat when tiny sprouts appear on each legume. They can be eaten immediately or stored in the refrigerator for 3–4 days.

You can sprout legumes even if you do not use legumes for cooking. It does not take very much time to fill a bowl with water and soak a few chickpeas or lentils, and once you do it a few times, you will easily get into the routine. Some stores even sell special containers for storing legumes during the sprouting process.

Table 1 provides a list of practical pointers for people who want to increase their intake of legumes. Table 2 summarizes useful tips for cooking with legumes. Consider attaching both to your refrigerator door and sharing them with your patients.

TABLE 1.

Practical Pointers for Increasing Your Intake of Legumes

Make sure you always have lentils in your pantry. They are the quickest legume to prepare.

Buy legumes even if you are not sure when you are going to use them. Dry legumes are good to have on hand and rarely spoil.

The next time you enter the kitchen to cook, even just for 20 minutes, boil a pot filled with water and lentils. Once you finish your dinner, the lentils will be ready to cool and store in the refrigerator for later use.

Save time by preparing the whole package of lentils instead of just what you need right now. Store half of the leftovers in the freezer and the other half in the refrigerator.

Soaking legumes? Make a double portion and freeze the soaked legumes for future cooking.

Use the cooked legumes in your refrigerator as a side dish with your dinner, or add them to your next soup or stew.

Bring a legume salad to work for lunch.

When your refrigerator legumes are almost gone, defrost some frozen ones to replenish your supply.

Once you become comfortable cooking legumes, try preparing two different kinds at one time.

TABLE 2.

Tips for Cooking With Legumes

Soak larger legumes such as chickpeas and kidney beans for 24 hours in cold water before preparing.

When preparing legumes other than lentils, add the salt at the end of the cooking process.

Legumes absorb a lot of water. Add at least 3 cups of water to each cup of legumes you cook.

Drain prepared legumes well before storing. It will increase their shelf life and improve their quality for later cooking.

During cooking, use a ladle to occasionally remove the foam that rises to the top.

Legume salads taste even better when allowed to marinate with the other ingredients for at least 30 minutes before serving.

Use the legume cooking liquid instead of water when you process legumes to make hummus or other types of spreads or dips.

Add legumes to meat recipes. The taste combination is great!

Add a squeeze of lemon any time you feel that your legume salad or soup needs more flavor.

Ready for a challenge? Try undercooking legumes for salad, until they are just partially soft. Then let them stand in the dressing for more than 30 minutes for a great texture and taste.

Conclusions

Nutrition has moved from being viewed only as a preventive modality to being recognized as a disease management tool. Incorporating healthy nutrition into both your own life and your clinic routines might be a meaningful change that you can implement one bite at a time. Just as you would advise your patients, start with a few small changes, and when those become habits, think about bigger ones. The time for nutritious food is now.