Evaluation of Beans as Food

Beans are a low-quality food for a number of reasons. First, beans are very hard to digest because they contain a combination of sugar, starch, and protein. Second, beans are very acid because of their high sulfur content (read article on acid/alkaline balance). Third, the protein in beans is of low biological value. Biological value is defined as “the percentage of absorbed nitrogen retained for growth and maintenance.” According to Heinz,^* peas and beans have a biological value of 40 as compared to whole egg, which has a biological value of 94. Then why are beans lauded as an excellent source of protein? If you explore the protein column of Agriculture Handbook No. 8, looking for high-protein foods, beans will stand out as containing 22.5% protein—a relatively high amount. However, the 22.5% is for dried beans. But beans are not eaten in their dehydrated state. Once the water is removed from any food that is primarily water, its nutritive content will misleadingly rise by huge factors. For beans that have been rehydrated through soaking and cooking (which is the way they are eaten), the protein content is under 8%.

If the protein content of dried beans is to be compared with that of other foods, the comparison must be made with all foods on a dry basis. Then, the biological values of the foods must also be taken into account. In this case, codfish would have seven times as much available protein as do beans. A similar error resulted in the misconception that bananas are extremely high in potassium.

This article is adapted from Robert Chuckrow, The Intelligent Dieter’s Guide, Rising Mist Publications, Briarcliff Manor, NY, 1997.

^*Nutritional Data, published and distributed by H. J. Heinz Company, Pittsburgh, PA, 1958, pp. 54–55.