Green beans (string beans) have the same nutritional benefits as other common beans such as lima beans, mung beans, kidney beans, pinto beans, and navy beans.
Common beans are low in fat and offer an excellent source of protein, fiber, and complex carbohydrates. They are also a very good source of folic acid and molybdenum. They provide significant amounts of iron, phosphorus, magnesium, manganesese, and potassium.
The major health benefit of common beans is their ability to lower cholesterol due to their rich source of fiber. Studies have shown that the high fiber contained in beans prevents blood sugar levels form rising too rapidly after a meal. This makes beans an especially good choice for individuals with diabetes, insulin resistance, or hypoglycemia.
Common beans promote heart health due to their fiber, antioxidants, folic acid, vitamin B6, and magnesium. Folic acid and vitamin B6 help to lower levels of homocysteine, which is an amino acid that is an intermediate product in an important metabolic process called the methylation cycle. Elevated blood levels of homocysteine are an independent risk factor for heart attack, stroke, and peripheral vascular disease. These elevated blood levels are found in 20 to 40 percent of patients with heart disease. Research has indicated that beans are also protective against cancer.
Studies conducted by the U.S. Department of Agriculture, revealed that richly colored dried beans offer a high degree of antioxidant protection. Small red kidney beans are rated the highest, just ahead of blueberries.