Beans and vSimilar Vegetables as Food 163 i 



nutritive value 

 In a discussion of the nutritive value of a food it is not sufficient to con- 

 sider only the amounts and the properties of the various nutrients contained ; 

 of equal importance is the extent to which these nutrients may be used 

 by the body, or, in other words, their digestibility. Hence, a conclusion in 

 regard to the nutritive value of the legumes must rest on a consideration 

 of their digestibility as well as of their composition. 



Nutrients contained by the legttnies 



The legumes are called a protein food because of their high protein con- 

 tent; like many other vegetable foods, however, the majority of them show 

 a high percentage of carbohydrate. Soy beans are conspicuously lacking 

 in carbohydrate, and for this reason they are of use in diabetic dietaries. 

 Peanuts are characterized among the legumes by their high fat content, 

 which has caused their extensive use commercially for the manufacture 

 of peanut oil and peanut butter. Protein is used by the body for the de- 

 velopment and the repair of tissue; it is also a source of energy, but in a 

 properly balanced dietary it should furnish only from 10 to 15 per cent of 

 the total energy value, the rest being supplied by carbohydrates and 

 fats. 



In addition to furnishing protein and energy-giving substances in large 

 proportions, the legumes are a valuable source of potassium, phosphorus, 

 iron, and calcium. Like milk, fruit, and vegetables in general, the legtimes, 

 with the exception of peanuts and lentils, belong to the group of foods 

 that are so necessary in the diet for the purpose of preventing an excess 

 of acid in the system, which condition might arise from a too exclusive 

 use of meat, eggs, and cereals. 



Composition of the various forms of legumes. — The percentage composition 

 of the legumes is influenced by the form in which they are used. Thus, 

 the forms in most common use are: (i) in the pod, such as string beans; 

 (2) shelled, such as green peas and green lima beans; (3) shelled and dried, 

 such as navy beans, kidney beans, lima beans, peas, and lentils. In a 

 given weight of these three forms there is the least amount of water in those 

 that are dried; consequently, the percentage of protein and other nutrients 

 is higher than in the case of the fresh legumes. The added amount of 

 carbohydrate contained in the pods also tends to decrease the percentage 

 of protein in the fresh, unshelled legume, such as the string bean. This 

 concentration of nutrients is shown in the dried bean, for example, which 

 contains 22.5 per cent protein in contrast to 2.3 per cent contained by the ' 

 fresh string bean. 



Although the green legumes do not show so high a concentration of 

 nutriment as do the dried legumes, their value in the diet must not be 



