Eating just 1 serving daily of legumes such as beans, chickpeas, lentils and peas can significantly reduce "bad cholesterol" and the risk of heart disease, found a study published in CMAJ (Canadian Medical Association Journal).
High cholesterol levels are associated with increased risk of cardiovascular disease, yet they are modifiable through diet and other lifestyle choices. Most chronic disease prevention guidelines recommend consumption of non-oil-seed legumes (dietary pulses) such as beans, chickpeas, lentils and peas along with other vegetables and fruits as part of a healthy diet, although they have not made specific recommendations based on direct lipid-lowering benefits.
The study, conducted by researchers from many centres in Canada and the United States, reviewed 26 randomized controlled trials that included 1037 people. Despite variation between studies, the researchers found a 5% reduction in low-density lipoprotein (LDL) cholesterol in people who ate 1 serving (3/4 cup) of non-oil-seed legumes a day. Men had greater reduction in LDL cholesterol than women, perhaps because their diets are poorer and cholesterol levels are higher and benefit more markedly from a healthier diet. Some study participants reported stomach upset such as bloating, flatulence, diarrhea or constipation.
"The reduction of 5% [LDL cholesterol] in our meta-analysis suggests a potential risk reduction of 5%% in major vascular events," writes Dr. John Sievenpiper of the Clinical Nutrition and Risk Factor Modification Centre, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, with coauthors.
They note that although consumption levels of legumes is low in Western countries such as Canada and the United States, 1 serving a day "is reasonable and is currently consumed by many cultures without reports of adverse effects that would limit consumption."
"Canadians have a lot of room in their diets to increase their pulse intake and derive cardiovascular benefits," states Dr. Sievenpiper. "Only 13% consume pulses on any given day, and of those who do, the average intake is only about a half serving."
The authors hope this study will add to the body of evidence upon which dietary guidelines are based. Most current evidence is of low quality, and the authors call for more high-quality research.
"Because dietary pulse intake may have beneficial effects on other cardiometabolic risk factors, including body weight, blood pressure and glucose control, future systematic reviews and meta-analyses should evaluate the effects of such dietary interventions on these outcomes and others, to address factors that contribute to residual cardiovascular disease risk," the authors conclude.
The study involved researchers from Keenan Research Centre of the Li Ka Shing Institute, St. Michael's Hospital, The Dalla Lana School of Public Health, University of Toronto and the Hospital for Sick Children Research Institute, Toronto, Ontario; McMaster University, Hamilton, Ontario; American Heart Association, Houston, Texas; University of Saskatchewan, Saskatoon, Saskatchewan; Brigham and Women's Hospital and Harvard Medical School, Cambridge, Massachusetts; The Cleveland Clinic, Lyndhurst, Ohio; Pennsylvania State University, University Park, Pennsylvania; University of Guelph, Guelph, Ontario; and Queen's University, Kingston, Ontario.