Studies in the Food Value of Fruit
At the University of California, Prof. M. E. Jaffa has carried on, in co-operation with the United States Department of Agriculture, a number of investigations which have to do with the food value of fruits and nuts, the special object of this and the earlier work which it continues being to study the value of such foods when they constitute an integral part of the diet. Nine dietary studies and thirty-one digestion experiments were made, part of them with persons who had lived for a number of years on a strictly fruit and nut diet, and others with university students who had been accustomed to the ordinary fare. In the majority of the dietary studies, and all but one of the digestion experiments, fruits and nuts constituted all or almost all of the diet. Thus, in one series of tests the daily ration consisted of apples and bananas, alone or in combination, eaten with walnuts, almonds, Brazil nuts, or pecans. In other experiments different combinations of grapes, pears, figs, walnuts, and other fruits and nuts were eaten with small quantities of milk, cereal breakfast foods, etc., the latter articles being taken simply to give a relish to the experimental dietary combinations, some of which were rather unusual. In connection with this work, the nutritive value of individual fruits and nuts was studied, and many data were collected and summarized regarding the composition and energy value of these materials, an interesting feature of the work being a comparison, on a pecuniary basis, of these and some common foods as sources of protein and energy. In general, it may be said that the chief nutrients in fruit consist of sugars and other carbohydrates and in nuts of protein and fat. In other words, while both fruits and nuts furnish the body with energy, nuts furnish some building material (protein) as well. Some idea of the range may be gained from the fact that at ordinary retail prices in the United States, ten cents expended for fresh grapes will supply the body with about 830 calories of energy, and in the case of dried apples or apricots will supply about 1,200 calories, as compared with 6,600 calories from ten cents' worth of wheat flour. In the case of almonds, this sum will supply .08 pound protein and about 1,100 calories of energy, and in the case of peanuts .28 pound protein and about 2,800 calories, while expended for cheese it would provide .17 pound protein and about 1,300 calories, and for flour .46 pound protein as well as the large amount of energy noted above. Although some of the dietaries showed that it is quite possible to obtain the needed protein and energy from a fruitarian diet, the majority of those studied fell below the tentative dietary standards. It is hardly just to ascribe this entirely to the form of diet, as the same people might have consumed no larger quantities of nutrients on an ordinary mixed diet. The nutritive value of the fruitarian diet is, perhaps, most clearly shown in the case of one of these subjects, a university student, who, though entirely unaccustomed to such fare, gradually changed from an ordinary mixed diet to one of fruits and nuts, without apparent loss of strength or health. He was then able for the eight days of the experiment to carry on his usual college duties, and for a part of the time also performed heavy physical work on an exclusive fruitarian diet, without material loss of weight. The daily cost of the fruitarian diet per capita varied from eighteen to forty-six cents, values which compare favorably with those of an ordinary mixed diet. Although it is undoubtedly advisable to wait until more data have been gathered before making definite statements regarding the digestibility of different fruits and nuts, enough work has been done to show that they are quite thoroughly digested, and have a much higher nutritive value than is popularly attributed to them. In view of this, it is certainly an error to consider nuts merely as an accessory to an already heavy meal, and to regard fruit merely as something of value for its pleasant flavor or for its hygienic or medicinal virtues. As shown by their composition and digestibility, both fruit and nuts can be favorably compared with other and more common foods. As sources of carbohydrates, fruits at ordinary prices are not expensive; and as sources of protein and fat, nuts at usual prices are reasonable foods. In the investigations at the University of California, the question of the wholesomeness of a long-continued diet of fruit and nuts is not taken up. The agreement of one food or another with any person is frequently more or less a matter of personal idiosyncrasy, but it seems fair to say that those with whom nuts and fruits agree can, if they desire, readily secure a considerable part of their nutritive material from such sources.— Scientific American.