The Indians of Central and South America first cultivated the common bean, writes nutrition educator Audrey Ensminger in "Foods and Nutrition Encyclopedia." Green shell beans, such as string beans or snap beans, are picked when fully grown, but before they have ripened and turned hard. Dry beans, such as kidney and navy beans, are picked when fully ripened and consumed cooked. Common beans of all varieties have "much greater food value than most other kinds of vegetables," Ensminger writes.
History
A century ago, nutrition textbooks first considered dried and fresh beans as two distinct classes because they differ so widely in use and nutrition value. In the 1913 text "Nutrition and Diet: A Textbook for Secondary Schools," with a revised version still in print, New York educator Emma Conley noted the differences. Fresh beans such as string beans, shelled kidney beans and lima beans contain 60 percent or more water, whereas dried lima and navy beans contain 12 percent or less. Fresh beans contain 2 percent to 9 percent protein, while dried beans contain around 20 percent. Both types contain less than 2 percent fat, and fresh beans contain 7 to 30 percent carbohydrate, while dried beans contain around 60 percent.
Significance
String beans compare with other green beans in nutritive value, Conley noted, while shelled fresh beans, such as lima beans, compare with vegetables such as potatoes, carrots, turnips and yams, though the lima beans contain much more protein. Dried beans compare nutritionally to cheese, nuts and chocolate, which are other nutrient-dense foods. Dried beans contain more protein than meat, fish, eggs and milk and as much as cheese, she observed.
Benefits
Ensminger confirms that more recent studies continue to show that dry beans contain from 23 to 25 percent protein, 61 to 63 percent carbohydrates and about 1.5 percent fat. Their protein percentage means they can be used as a meat substitute. Green beans are also rich in vitamins and protein, while stringless or snap beans provide a rich source of vitamins A, B and C.
Types
Dry beans refer to both beans that are dry-packed and those that are precooked in cans, but do not include string beans, soybeans or green beans. Dry beans include pinto, kidney, great northern, garbanzo, navy, lima, adzuki, black-eyed, mung, pink, small red and black beans, according to the Utah State University Cooperative Extension. Fresh beans include snap beans, green beans and yellow wax beans, notes the Ohio State University Extension.
Function
If you are looking to make beans part of a healthy diet, eat fresh beans for vitamins and fiber and dry beans for fiber and protein, which make them an ideal candidate as a building block of a weight-loss diet. Most dry beans contain all the essential amino acids except methionine, Utah State notes, which can be obtained by adding corn, rice or meat to the diet. Dry beans also contain B vitamins, iron, calcium and magnesium.
References
- "Foods and Nutrition Encyclopedia"; Audrey Ensminger; 1994
- "Nutrition and Diet: A Textbook for Secondary Schools"; Emma Conley; 1913
- Utah State University Cooperative Extension: Audrey Ensminger
- Michigan State University: Eat Beans for Good Health
- Ohio State University Extension: Growing Peas and Snap Beans in the Home Garden
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