A Laboratory Hand-booh for Dietetics
By Mary Swartz Rose, Ph.D. New York: The Macmillan Company, 1912. Pp. x + 127.
The interest of Dr Rose’s hand-book is by no means limited to the small group of students for whom it was intended. Among the topics with which the well informed person is supposed to be acquainted, the science of dietetics is rapidly taking a more prominent place. Nearly everyone has at some time been placed by his (or her) physician upon a diet restricted in one of its main constituents,?protein, fat, and carbohydrate. We hear of the “purin-free” diet for epileptics or for gouty people, and the “low-protein” diet for those suffering from intestinal disorders or incipient tuberculosis. We are advised to eat salads for the sake of the mineral elements contained in green vegetables, and to use brown rice and whole wheat flour rather than the common white varieties in order to secure more of the same mineral substances.
The fuel value, of “food value” of certain articles of diet is a phase very commonly heard and but little understood. Magazines and newspapers are urging women readers to regulate their household expenses so as to get the greatest “food value” for the outlay. How this is to be done is a question,?and to the housewives who fesent being nagged by the public press it has become a fighting question. Dr Rose’s manual will be welcomed as illuminating a very dark region in many minds. The reference tables are so complete, and the directions so explicit, that anyone equipped with curiosity, persistence and elementary arithmetic can reduce an ordinary dietary to its units of fuel value, or Calories, and compare several dietaries as to nourishment and cost.
So far, so good. But having found what foods are cheapest and at the same time highest in Calories, the utmost common sense and discretion will be needed in making up an ideally efficient dietary. Pickled cucumbers contain one-third more Calories than does consomme and are vastly cheaper. Crystallized ginger yields about three times as much fuel value as roast chicken, and Calorie for Calorie the cost is about the same. Chocolate gives more than four times as many Calories as an egg, at less cost; while peanuts give one and a half times as many Calories as broiled lamb chops for one-third the price. At the prospect of a dietary controlled entirely by the factors of fuel value and cost, the sturdiest imagination may well grow faint.
Dr Eose makes very clear the nature of a Calorie. She says, “Since energy is easily transformed into heat, and this form is readily measured, a heat unit, the Calorie, has been adopted as the most convenient measure of energy. One Calorie is the amount of heat required to raise one kilogram (2.2 pounds) of water one degree Centigrade, of one pound of water four degrees Fahrenheit. Expressed in terms of work, it represents that required to lift one pound through the distance of 3087 feet or 3087 foot-pounds.
“The total energy value of each of the foodstuffs (proteins, fats, and carbohydrates) has been determined by burning it in a calorimeter in pure oxygen, under such conditions that all the heat evolved is taken up by water surrounding the vessel in which the combustion occurs, and the increase in the temperature of the water measured by a delicate thermometer’. In the body, combustion of protein is not quite so complete as in the calorimeter, and there are usually some losses due to failure of complete digestion of each kind of foodstuff, so that the available energy is somewhat less than the total energy value. In a healthy human being, on an ordinary mixed diet, the fuel value of each foodstuff is on the average as follows: protein 4 Calories per gram, fat 9 Calories per gram, carbohydrate 4 Calories per gram.”
The book is divided into three parts: I. Food Values and Food Requirement; II. Problems in Dietary Calculation; III. Reference Tables. There is an appendix on the “Equipment of a Dietetics Laboratory,” with a list of the furniture and utensils for a class of thirty students. One of the most helpful sections is that upon the modification of cows’ milk to a required formula, and others of great practical value are on the “Analysis of a Recipe,” and “Scoring a Dietary.” It is hardly fair, however, to select these chapters for special praise when the entire manual is on so high a level of excellence. A. T.
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