It is not within the scope of this work to discuss the details of the economic value of food, but brief reference to one or two facts will emphasise the importance of this topic.

It is estimated that the annual cost of food production in the United States is at least three billion dollars, and the cost of production must be doubled in estimating the price paid by the consumer.

Naturally, many attempts have been made to tabulate the cost of feeding large bodies of men employed by contract, or patients in hospitals and institutions. Some of these studies have been conducted with great care, but on a comparatively small scale, as in the case of the economic diets of the French factory operatives in Massachusetts, the penny dinners furnished to London school children, and the researches made by Mrs. Richards and Miss Talbot upon pupils at the University of Chicago. Calculations upon a much larger scale are available as a basis for the supply of armies and navies. (See the section upon Diet for the Army and Navy).

The economic value of food cannot be estimated exclusively from its weight, and, as suggested by Williams, a pound of biscuit may contain as much fuel as a pound of beefsteak, and yet the body may be able to assimilate more of the beefsteak and derive more energy therefrom; and it is the chemical processes of Nature which convert such substances as grass, which are not assimilable by the human organism, into the flesh of the ox, which is readily digested by man.

It is economical in employing large bodies of men at manual labour to feed them well, for they will do much more work proportionately.

Carbohydrates check albuminous waste, and, like fats, yield both heat and mechanical work; hence good bread, sugar, and potatoes are all economical foods for the labourer. Unlike the other classes of foods, however, they do not produce brawn, and do not enter into the actual structure of the tissues to any great extent, although the carbohydrates may be found existing as glycogen in some of the tissues,like the muscles and liver. In general, they seern to be more easily metabolised than fats or proteids. Assuming 3,500 calories as the necessary daily standard for a labourer, one pound of flour yields 0.11 pound of protein and 1,650 calories; a pound of dried beans yields 0.22 pound of protein and 1,590 calories; but cabbage yields only 0.02 protein and 150 calories per pound, and oranges 0.01 protein and 160 calories.

Atwater's Table Of Digestibility Of Nutrients Of Food Materials

In the Food Materials Below

OF THE TOTAL AMOUNTS OF PROTEIN, FATS, AND

CARBOHYDRATES THE FOLLOWING PERCENTAGES

WERE DIGESTED:

Protein.

Fats.

Carbohydrates.

Meat and fish

Practically all

79 to 92

Eggs................................

"

96

..

Milk

88 to 100

93 to 98

?

Butter

98

.

Oleomargarine

96

Wheat bread

81 to 100

?

99

Corn (maize) meal

89

?

97

Rice

84

?

99

Peas

86

?

96

Potatoes

74

?

92

Beets

72

?

82