Bazzano et al1 used data from the First National Health and Nutrition Examination Survey Epidemiologic Follow-up Study and found that people who ate legumes regularly had a reduced risk of coronary heart disease (CHD). They suggested that "increasing legume consumption may be an important part of dietary interventions to reduce the risk of CHD," and that calcium, fiber, folate, magnesium, potassium, or vegetable protein may be protective. An increase in dietary copper intake with an increase in legume consumption also may have contributed to their results because copper deficiency is the only nutritional insult that (1) elevates cholesterol, blood pressure, and uric acid; (2) has adverse effects on electrocardiograms; (3) impairs glucose tolerance; and (4) promotes thrombosis and oxidative damage.2 Experiments with fiber or magnesium, for example, reveal single effects on cholesterol levels or electrocardiograms, but not on several of these characteristics simultaneously.
Klevay LM. Copper in Legumes May Lower Heart Disease Risk. Arch Intern Med. 2002;162(15):1780-1781. doi: