The most widely distributed group of food substances and those which are our chief supply of energy are the carbohydrates. Their chemical composition includes the three elementscarbon, hydrogen, and oxygen. They are obtained from fruits, vegetables, cereals, honey, sugar, milk, and preparations such as breads, candy, jelly, jam, marmalade, tapioca, sweet desserts, cornstarch, and other concentrated sweets, and starches. They are found in food both in the form of starches and complex sugars, of which there are many kinds. In the process of digestion these are broken down to simple sugars before the body can use them. The most common simple sugar is called glucose. It is the form in which the body uses all carbohydrates for the production of heat and energy.
A well balanced mixture of the foods containing starch and sugar is advisable in supplying this very necessary food element. Starches are rather slowly digested, while sugars are more quickly digested and absorbed, so that a fair proportion of foods containing each will tend to supply a better ration than where either is used pre-dominantly. Simple sugars, such as glucose, are absorbed very promptly on entering the intestinal tract. A certain amount of glucose circulates constantly in the blood stream. Any excess is stored in the liver, muscles, and skin as glycogen or body starch. Holt and Tales care-fully checked the carbohydrate content of the diets of 100 healthy children and found that 51 per cent was sugar, including milk sugar and fruit sugars, and 49 per cent was starch.
Amount Required. Carbohydrates are used in the body primarily for the production of heat and energy. Since the production of heat and energy is the greatest demand that we make of food, our diets should contain a large amount of these substances. Nutritionists state that they should provide from 50 to 60 per cent of the food value of the diet. The use of sufficient carbohydrates avoids the necessity of using a large amount of protein as energy producing food. Thus they may be thought of as protein sparers. The advantage of this can be seen in lessening the work of the liver and kidneys. In periods of special training for competitive athletic contests, the men are served a diet relatively low in proteins and high in carbohydrates. In its relation to fat consumption, a ratio of 3 or 4 parts of carbohydrates to one part of fats is thought to be most satisfactory. Joslin states that the average diet for a normal adult man contains 400 grams of carbohydrates, 100 grams of proteins, and 100 grams of fats, a total of 2900 calories. People in India take about 484 grams of carbohydrates daily, while Eskimos use only about 52 grams. He gives the following table which is of interest:
Eskimo Weight P C F Calories
Kg. 282 52 141 2604
Bengali 50 52 484 27 2390
Europe 70 118 512 65 3105
America 70 100 400 100 2900
The old Voit standard for a laboring man called for 500 grams of carbohydrates, 118 grams of proteins, and 56 grams of fats.
We believe from our experience in the treatment of diabetic patients, as well as non-diabetics, that a more ideal diet is one that maintains a high ratio of carbohydrates to fats. We have used diets containing two parts of carbohydrates to one of fats for ten years in the treatment of diabetes, and more recently, diets containing three and four parts of carbohydrates to one of fats.
In the selection of foods to supply the carbohydrates, we advise first a liberal amount of fruits and vegetables because of the additional minerals, vitamins, and cellulose which they supply. Cellulose is a form of carbohydrates which is found in fruits, vegetables, and grains, but is not digested. It is valuable for its bulk and water holding capacity. The carbohydrate content of fruits and vegetables is not high, however, so they should be supplemented with cereals and breads, and further, as necessary, with moderate amounts of concentrated sweets and starches.
The Excessive Use of Sugar. The tendency at present is toward the overconsumption of concentrated carbohydrates. The annual consumption of cane sugar has in-creased from 8.8 to 108 pounds per capita in a hundred years. Statistics show that in 1931 school children spent $40,000,000 for penny candy alone. It has been estimated that $1,000,000 is spent daily in the United States for candy, and that $500,000,000 is spent yearly for ice cream and sweet drinks. An interesting check was made on the type of food most liberally consumed in a large cafeteria where patrons were allowed as much food as they desired for a certain moderate sum. The majority of guests took additional desserts or other forms of concentrated sweets. Mendel of Yale, in an article entitled, The Changing Diet of the American People, pointed out the dangers of this trend unless it is checked, because of the lack of many essential food elements that are not found in these concentrated carbohydrate foods.
An excessive amount of carbohydrates is not advisable because it may cause digestive disturbances and the ac-cumulation of superfluous body fat. The body is able to store a limited amount of carbohydrates in the form of glycogen in the liver and muscles. McLester states that this varies from 93 to 233 grams, one-fifth to one-half being stored in the liver. Beyond this, additional quantities are changed into body fat and stored as such.
Effects of an Insufficient Supply. One having an in-sufficient supply of carbohydrates will likely experience a drop in blood sugar, and have symptoms of nervousness, perspiration, emotional upset, headache, or weakness. Any unusual or prolonged physical strain may bring on a headache or trembling, which can be relieved quickly by a drink of fruit juice or some other carbohydrate food. This is not an uncommon experience. But there are those even who feel these symptoms in the late forenoon and late afternoon after ordinary work. If we test the blood sugar at these times it is low, just as if such a person were burning the carbohydrates in his food faster than they are supplied. This condition may be prevented when a small meal is eaten about halfway between the regular meals.