Mother was right all along. Grandma also told us they were good for us. So why do Americans eat green leafy vegetables only about once or twice a week? Why is lettuce the only green vegetable many Americans ever see? Why are cabbage, broccoli and spinach rarely seen at the American dinner table, when green vegetables are recognized as one of the most inexpensive sources of so many essential nutrients?

Low in calories, leafy vegetables are ideal for weight management. They are useful for reducing the risk of cancer and heart disease, since they are low in fat, high in dietary fiber, and rich in folic acid, vitamin C, potassium and magnesium, as well as containing a host of phytochemicals such as isothiocyanates, indoles and beta-carotene. Adding one daily serving of green, leafy vegetables can lower the risk of cardiovascular disease by 11 percent, as well as lower the risk of all causes of death.

Green vegetables are rich in health-promoting flavonoids and carotenoids, potent antioxidants with cancer-preventive properties. Cabbage, cauliflower, Brussels sprouts and broccoli are rich in indoles and isothiocyanates, which protect against colorectal cancer. A regular use of green, leafy vegetables reduces the risk of stomach cancer by 30 percent or more.

Green vegetables are also an important source of iron and calcium for any diet. Because of their high magnesium content and low glycemic index, green, leafy vegetables are also valuable for persons with Type 2 diabetes. Adding one serving per day of green, leafy vegetables can lower the risk of diabetes about ten percent. The high level of vitamin K in greens makes them important for the production of osteocalcin, a protein essential for bone health. The risk of hip fracture in middle-aged women was decreased substantially by adding a daily serving of green, leafy vegetables.

Lutein and zeaxanthin, carotenoids found in dark green, leafy vegetables, are concentrated in the macular region of the retina, and protect against age-related macular degeneration, the major cause of blindness in the elderly. For millions of children around the world, green, leafy vegetables provide an important source of vitamin A to prevent blindness.

Sometimes lettuce and other fresh vegetables become contaminated. In 2006, an E. coli O157:H7 outbreak, associated with contaminated bagged baby spinach, resulted in 205 confirmed illnesses and three deaths. Food and Drug Administration (FDA) investigators reported the outbreak was probably caused by irrigation water contaminated with cattle feces, grazing deer or wild pigs on the ranch.

Green, leafy vegetables provide good nutrition in a variety of colors from bluish-green kale to bright kelly-green spinach. Young plants with small, tender leaves have a mild flavor, while many mature plants have tougher leaves and stronger flavors. Collards, Swiss chard, bok choy and spinach provide a mild flavor, while arugula and mustard greens have a stronger peppery flavor.

Winston Craig, Ph.D., R.D., is a professor of nutrition at Andrews University.

Regular use of greens lowers the risk of cancer, cardiovascular disease and diabetes.

Greens can prevent blindness.