A new study, published in the Canadian Medical Association Journal, shows that eating a daily serving of cooked legumes is linked with lower levels of low-density lipoprotein (LDL) cholesterol – or bad cholesterol.

Legumes are a class of vegetables that includes beans, peas, and lentils. They are typically low in fat, contain no cholesterol, beneficial fats, and soluble and insoluble fiber. A suitable source of protein, legumes can be a healthy substitute for meat, which has more fat and cholesterol.

"We found a five percent reduction in bad cholesterol with one serving of legumes a day over six weeks on average," said study co-author Vanessa Ha, a research coordinator at the Clinical Nutrition and Risk Factor Modification Center at St. Michael's Hospital in Toronto.

Low-density lipoprotein cholesterol is one of the most important risk factors for cardiovascular disease. When too much LDL cholesterol circulates in the blood, it can slowly build up in the inner walls of the arteries that feed the heart and brain – possibly causing atherosclerosis.

Although heart attacks are unpredictable, higher levels of LDL cholesterol increase your risk.

Expert groups define the levels of LDL cholesterol as follows:

• An LDL of less than 100 milligrams per deciliter (mg/dL) is optimal.
• An LDL of 100 to 129 mg/dL is near-optimal.
• LDL between 130 and 159 mg/dL is borderline high.
• LDL cholesterol between 160 and 189 mg/dL is high.
• An LDL of 190 mg/dL or more is very high.

The researchers from the St. Michael’s Hospital evaluated data collected from 26 clinical trials involving 1,037 individuals who were primarily middle-age. Some of the trials involved healthy adults, while others included participants who were at moderate risk for heart disease. They found that people who ate one serving (3/4 cup) of non-oil-seed legumes a day exhibited a 0.17 point (measured in milimoles/Liter) or 5 percent reduction in LDL cholesterol.

The study also found a greater reduction in LDL cholesterol in men than women. The researchers believe men generally have poorer diets and higher cholesterol than women. This is why they show better improvements from a healthier diet.

Despite the reduction in LDL cholesterol, some participants did experience minor side effects from the diet, such as bloating, flatulence, diarrhea, or constipation. However, the researchers write that the suggested one serving a day can help the heart without the side effects. 

The researchers also believe that eating legumes daily could have other positive effects that may protect against cardiometabolic problems. These could include improving body weight, blood pressure and blood sugar control.

Despite their health benefits, legumes still aren't a common food at mealtimes. By one estimate, Americans currently eat 0.2 servings daily on average.

“There's room or the potential to increase legume consumption as entrees, in soups or salads, or as a snack, like hummus,” Ha said. 

Additional Resource:

Ha, V., Sievenpiper, J. L., de Souza, R. J., Jayalath, V. H., Mirrahimi, A., Agarwal, A., ... & Jenkins, D. J. (2014). Effect of dietary pulse intake on established therapeutic lipid targets for cardiovascular risk reduction: a systematic review and meta-analysis of randomized controlled trials. Canadian Medical Association Journal, 186(8), E252-E262.