A diet rich in legumes — the umbrella term for beans, lentils, chickpeas, and soybeans — as well as soy foods like tofu may improve heart health by lowering the risk of developing high blood pressure, a new analysis found.
The latest findings suggest that eating more of these plant proteins, especially in place of less heart-healthy proteins like red meat or processed meats, could provide significant benefits for your ticker.
The Review Combined Multiple Soy and Bean Studies
For the new investigation, researchers combined data from 12 observational studies from the United States, Europe, and Asia that looked at legume or soy consumption and high blood pressure risk. In observational studies, scientists only track participants; there is no intervention, like taking a medicine or changing a behavior.
Legumes include beans, lentils, chickpeas, peas, and soybeans. Soy foods include tofu, soy milk, edamame, tempeh, miso, and other foods made from soy.
The number of study participants ranged from just over 1,000 to nearly 90,000, and most of the included studies had long-term follow-up and large sample sizes. They also adjusted for multiple factors that could influence blood pressure.
Key findings included:
People who ate the most legumes or soy foods had a lower risk of high blood pressure. Compared with people who ate the least legumes, those who ate the most had a 16 percent lower risk of developing high blood pressure. Meanwhile, people who ate the most soy foods had a 19 percent lower risk of high blood pressure compared with those who ate the least.
Benefits for legumes leveled off at around 1 cup per day. When researchers used the information to model benefits at specific amounts of legumes, risk kept dropping as legume intake rose up to about 170 grams per day — roughly 1 cup of cooked beans, lentils, chickpeas, or peas — which was linked with about a 30 percent lower risk.
Benefits for soy foods maxed out at about one serving. In the modeling analysis, most of the lower risk was seen around 60 to 80 grams per day. That’s roughly a single serving of tofu, tempeh, edamame, or soy milk. Little extra benefit appeared at higher amounts.
Because the study was observational (meaning people weren’t randomly assigned to eat more legumes and soy) the findings can only prove a link, not cause and effect.
How Beans May Support Healthy Blood Pressure
“Legumes are high in fiber, minerals, and bioactive compounds that could contribute to reduced hypertension risk,” says Dr. Aune. That includes potassium and magnesium, two minerals involved in blood pressure regulation.
When gut bacteria ferment some types of fiber, they produce short-chain fatty acids, which may help blood vessels relax and widen, he says.
“Legumes are also a source of L-arginine, an amino acid that can help nitric oxide production, which influences blood vessel dilation,” says Aune.
“Finally, there’s evidence that legumes and soy can reduce risk of overweight and obesity, which is a major risk factor for hypertension,” says Aune.
Eating Beans Also Leaves Less Room for Meat
“The heart benefits of beans and soy-based foods is partly about substitution: what people aren’t eating when they choose plant-based foods,” says Joel Kahn, MD, a cardiologist at the Kahn Center for Cardiac Longevity in Bingham Farms, Michigan, who was not involved in the review.
Dr. Kahn offers the example of his latest lunch — a tempeh, lettuce, and tomato sandwich instead of a traditional BLT. The tempeh adds protein and fiber without the salt and saturated fat that bacon would bring, he says.
Pay Attention to Added Salt
Canned beans can be a significant source of added salt. For example, a cup of Bush’s Black Beans has about 40 percent of the recommended daily intake. Could that potentially affect the benefits for high blood pressure and heart health?
That’s an important question, but not one that can be answered with the available data, says Aune. Further research is needed, he notes.
“It’s possible that there may be a difference, so it may be prudent to choose legumes that don’t have sodium added,” he says.
You can also buy low-sodium canned beans or rinse the beans before using them to reduce the sodium level.
Expert Tips for Adding More Legumes and Soy to Your Diet
The following tips can help you incorporate more of these heart-healthy plant proteins into your diet.
Take Inspiration From Diverse Cultures
The study findings fit with long-standing patterns seen in places known for healthy aging, says Kahn.
“A common theme in areas with exceptional health and longevity worldwide is the reliance on legumes as a food staple, often with soy products like tofu and tempeh featured,” he says.
Aune recommends looking to diverse cultures for inspiration. “Many traditional diets emphasize more legumes and soy, and exploring how different cuisines use legumes and soy can be both an interesting and tasty way of increasing your own intake of these foods,” he says.
Start With a Sprinkle
If this style of eating is new for you, you don’t have to jump in all the way, says Leah Groppo, RD, at Stanford Health Care in California.
“Adding a sprinkle of beans to a salad or any kind of main dish can add fiber and more nutrition to a meal,” she says.
Try a ‘Protein Flip’
“Most Americans think the center of the plate is chicken, beef, or pork and then the side dishes that go with it are grains and vegetables,” says Christopher Gardner, PhD, professor of medicine at the Stanford Prevention Research Center in California.
“The protein flip is putting plants in the middle of the plate. The meat is no longer the centerpiece, but rather a flavoring or a side dish,” he says.
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