Legumes: Are they good for your heart?

When it comes to plant-based protein, legumes are hard to beat. Members of this family of plants (which includes beans, lentils, and peas) are also rich in complex carbohydrates — the healthy type that take a long time to digest. Legumes are also high in fiber, low in fat, and contain an array of vitamins and minerals.

“Substituting legumes for less-healthy forms of protein and carbohydrates can help prevent or manage common conditions that contribute to heart disease,” says Dr. Rani Polak, founding director of the Culinary Healthcare Education Fundamentals (CHEF) Coaching program at Harvard's Institute of Lifestyle Medicine.

Why? For starters, the protein in many meat and dairy products comes with cholesterol-raising saturated fat. And simple carbohydrates from refined grains — like white bread and white rice — have been stripped of their cholesterol-lowering fiber.

How legumes support heart health

Legumes contain two forms of healthy fiber: soluble fiber and resistant starch. Soluble fiber acts like a sponge in the digestive tract, trapping cholesterol-rich bile and allowing your body to eliminate it. Resistant starch breaks down in the large intestine, providing food for gut bacteria that produce short-chain fatty acids. Together with other fiber components, these substances may help lower cholesterol, blood pressure, inflammation, and body weight — all important causes of heart disease.

“Legumes are also quite filling, which can also help people eat less and lose weight,” Dr. Polak says. Eating legumes may also lower the risk of type 2 diabetes, probably because legumes have a low glycemic index, which helps control blood sugar levels. Having diabetes more than doubles the risk of developing heart disease.

Potential downsides from legumes

Like other high-fiber foods, legumes can cause intestinal gas, leading to bloating and flatulence. If you rarely eat legumes, ramp up your intake gradually. Keep eating them regularly and your intestinal bacteria will acclimate to the extra fiber and produce less gas over time.

Soaking beans overnight and cooking them in fresh water helps remove the gas-producing substances; soaking twice is even more effective. But that’s another reason people may avoid legumes; they think they’re too time-consuming to prepare. You can always use canned beans, however. And nearly all of the soaking and cooking time for beans is hands-off, Dr. Polak points out.

Incorporating legumes into your diet

Start by replacing some of the meat in your favorite dishes (such as tacos or pasta sauce) with low-sodium canned black or red beans. Lentils, which don’t require soaking, come in a variety of colors, including brown, green, and black. Tiny orange lentils (also called red lentils) cook in just five to seven minutes. Try Dr. Polak’s recipe (see “Orange lentil salad with feta and fresh herbs”). You can jazz it up by adding any combination of cooked whole grains, diced vegetables, or chopped nuts, he suggests.

 Here are some other ideas:

• Swap out part of a serving of rice with cooked lentils.
• Toss kidney beans or black-eyed peas into a green salad.
• Snack on edamame or try one of the many other ways to enjoy soybeans.
• Make soup with green or yellow split peas.
• Whip up some hummus or other dishes made with chickpeas, such as chana masala (chickpeas cooked with tomato sauce and spices).
• Seek out recipes that use beans, such as frijoles refritos (mashed, fried pinto beans simmered with onion and garlic) or pasta e fagioli (cannellini beans with small pasta shapes in tomato broth).

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