Carbohydrate

“ If we desire to know how much sugar a certain food will add to the metabolism, that is, the sugar value of the food, we must know both the weight of the food and how much of this weight is carbohydrate, how much is protein, and how much is fat. The sugar value will be the sum obtained by adding the weight of the carbohydrate, 58 per cent of the weight of the protein, and 10 per cent of the weight of the fat. ”

“ Bunge believes that a considerable amount of carbohydrate is stored as fat, since the total amount of glycogen in the liver never exceeds 150 grams, and there is a similar store in the whole mass of muscles. It is evident, therefore, that only a small proportion of carbohydrates is laid down as glycogen, and we must assume that the greater part of it is converted into fat. That fat accumulates in the body on a purely carbohydrate diet is proved beyond a doubt, and the formation of fat from sugar is considered proved by experimental evidence. ”

“ Thus if the composition of a food is 3-3/10% protein, 4% fat and 5% carbohydrate, one gram would contain .033 gram of protein, .04 gram of fat and 0.5 gram of carbohydrate. Hence one gram of milk would produce
But it is not necessary to estimate the fuel value of so small a quantity as one gram, and, since the value of protein, carbohydrates and fats is always the same it is more satisfactory to estimate the amount of the organic constituents contained in the entire given quantity of food, rather than stopping to figure out the fuel value of the small quantity. ”

“ There are some persons, perhaps, who do not realize that beside cane sugar many kinds of carbohydrate occur in our food. Glucose or grape sugar, for example, occurs not only in the fruit indicated by its name, but also in other fruits, in corn, in onions, and in the common vegetables. Glucose is especially suited to act as nourishing food. ”

“ Further, physiologists have learned that a certain small, but definite, amount of sugar in the blood is a necessary requirement in nutrition, and it is the function of the liver to maintain the proper carbohydrate level.
We must again emphasize the great importance of carbohydrate food; there is a far larger amount of starchy food consumed than of any other foodstuff, and it is more readily available as a source of energy. ”

“ Other species of plants always show considerable quantities of simple sugars in the vegetative tissues, and some even store up their reserve carbohydrate food material in the form of glucose or sucrose. Attempts have been made to associate the type of carbohydrate formed in cell synthesis with the botanical families to which the plants belong, but with no very great success. For each individual species, however, the form of carbohydrate produced is always the same, at least under normal conditions of growth. ”

“ It matters little whether the actual carbohydrate thus synthesised is starch, or sugar or inulin: the point is that energy has been gained from outside and bound up with the acquired material for further use. But modern physiology has carried matters much further than this, and especially in the three following directions. ”

“ As is well understood, the high percentage of carbohydrate, which in some cases may be very close to 100 per cent., greatly increases the food value of this variety of foods. Where the percentage is very high, the candies are necessarily hard, for all or nearly all the moisture is driven off in the making. In this case, as in other foods, the more water there is present, the more reduced is the total food value. ”

“ In fact, it is the form in which carbohydrate material is supplied to the tissues as needed. Normally, much of the sugar is used up by the blood and its cells in metabolism, giving rise to heat and energy. In muscles glycogen is probably digested as lactic acid, as before action muscle is neutral or slightly alkaline and after action acid.
When the liver is deranged and allows the glycogen to pass out into the blood too freely, or when the glycogen is not held as such but turned to sugar and passed out in large quantities, sugar in the urine or diabetes mellitus results. ”

“ Diabetes is a disorder of metabolism. There are other disorders of metabolism, but none so common as that of diabetes.
Carbohydrate, protein and fat.—The food supply of mankind is limited to the tissues of plants and animals, and the fuel in all such foods is either a carbohydrate, a fat, or a protein. Carbohydrates are starches and sugars; fats are oils, lards and complex materials such as may be found in brain, and egg yolk; protein is abundant in lean meat and cheese. ”

“ After this 5 grams of carbohydrates, or 75 grams of 5% vegetables, are added daily to the diet until the patient is taking 20 grams. Then the addition of 5 grams of carbohydrates is made every other day, using the fruits and vegetables belonging to the 10% and 15% carbohydrate group, until potatoes and oatmeal and finally bread can be tolerated unless sugar appears in the urine before this or the tolerance reaches 3 grams to each kilogram of body weight or, in other words, until a man weighing 150 pounds is consuming 225 grams of carbohydrates per day. ”

“ When, for example, the flow of bile is lessened, an incomplete emulsification of the fats exists and the fatty acids which are highly acid in character cannot be efficiently dissolved or neutralized, or when the liver is diseased and for this reason the conversion of glycogen into glucose is interfered with, the utilization of the carbohydrate foods is thus impaired. ”

“ The principal carbohydrates are starch, dextrine, cane-sugar or common table sugar, grape-sugar, the principal sugar in fruits, and milk-sugar, the natural sugar in milk. They are substances made up, as before stated, of carbon, hydrogen, and oxygen, but no nitrogen. They are important food substances, but are of themselves incapable of sustaining life.
The carbohydrates, both starch and sugar, in the process of digestion are converted into glucose. This is stored in the liver in the form of glycogen, which the liver has the power of manufacturing ”

“ The Carbohydrates comprise starch, sugar, gum, mucilage, pectose, glycogen, &c.; cellulose and woody fibre are carbohydrates, but are little capable of digestion. They contain hydrogen and oxygen in the proportion to form water, the carbon alone being available to produce heat by combustion. Starch is the most widely distributed food. It is insoluble in water, but when cooked is readily digested and absorbed by the body. Starch is readily converted into sugar, whether in plants or animals, during digestion. There are many kinds of sugar, such as grape, cane and milk sugars. ”

“ Of the common cereals rice contains more starch than any other and oats the least. Sugars are intimately related to starch and are included under the term starchy food or carbohydrate food. The carbohydrate matter in the flesh mentioned above, namely glycogen, is of the nature of a sugar. Among the typical sugar foods are beets, melons, and fruits, some of which contain large percentages of sugar. All fruits contain greater or less quantities of sugar, and that is true, also, of all vegetables. ”

“ Carbohydrate and fat unquestionably take precedence over proteid in this respect, and we may accept as settled the view that in all practical ways carbohydrate and fat stand on an equal footing as sources of muscular energy. ”

“ The carbohydrates include sugars, starches, cellulose, and the fibers of plants. Potatoes, sago, farina, and arrowroot are rich in them. Fats should be used with caution in disease, because they retard the formation of hydrochloric acid, which excites the pancreatic secretion, an important factor in digestion. Man can live better without a stomach than without a pancreas. Physicians realize that they must rely on diet rather than drugs to cure indigestion, as the food varies in its proportion of fat, protein, and carbohydrates ”

“ In the stomach, the hydrochloric acid helps to make it soften and swell, and then pepsin begins its digestion. Protein, like fat and carbohydrate, can be subdivided into smaller and smaller portions, finally being reduced to a form which the body can absorb, namely, amino acids, of which there may be 17 or 18 kinds from a single protein. ”

“ Flours, breads, biscuits, chocolates, breakfast-foods, macaroni, etc., containing only a slightly lowered percentage of carbohydrates, are no more entitled to be called “diabetic” foods than the normal foods themselves. It is true that, when a patient’s carbohydrate tolerance is well established, the use of foods containing 20, 25 and even 35 per cent. of carbohydrates might be permissible, when used under the direction of a competent physician ”

“ The carbohydrates are our chief source of heat and energy, and as previously stated, furnish sixty to sixty-five per cent of the total fuel value of our food. Each ounce of pure carbohydrate yields one hundred sixteenPg 30 calories of heat when burned. In caloric yield, they are equal to the proteins gram for gram, but yield less than one half that of the fats. If two thousand five hundred calories are again taken as our standard, then sixty per cent would make one thousand five hundred calories to be furnished by the carbohydrates. ”

“ Glucose (often called also dextrose, fruit sugar, or grape sugar) occurs widely distributed in plants, most commonly in the juices of ripening fruits, where it is usually associated with fructose and sucrose, the two hexoses being easily derived from sucrose by hydrolysis. Glucose is also produced by the hydrolysis of many of the more complex carbohydrates, by the action either of enzymes or of dilute acids; lactose, maltose, raffinose, starch, and cellulose, as well as many glucosides all yielding glucose as one of the products of their hydrolysis. ”

“ Compared to the protein, the carbohydrates and fats are relatively simple chemical substances, fairly stable and, hence, easy to study chemically. Proteins are excessively changeable, to which character they owe their name. Some proteins are called albumins. Egg albumin, egg white, is a typical protein possessing all of the essential protein characteristics. The carbohydrates and fats serve chiefly as fuels, while the proteins, besides providing energy, build or rebuild the living tissues of the body. A diet may be deficient in either fat or carbohydrate, [Pg 19] and still remain adequate. ”

“ It so happens that fat, which under suitable circumstances, is readily metabolized, fails to oxidize smoothly when less than a certain minimum of sugar is being used. The fats, it is said, burn in the fire of carbohydrates. If a perfectly normal person is deprived of carbohydrate and fed only fat and a little protein, certain products of incompleted combustion of fat will accumulate in the body. ”

“ The chief use of glucose, and of other forms of digested carbohydrates is in the formation of heat and energy. Glucose is oxidized chiefly in the muscles, producing carbon dioxid, water, and some lactic acid. Another function of glucose in the blood is to build up or form fat. Fat is a form of stored food which is not so readily available for use as are glycogen and glucose. ”

“ Avoid sweets, especially sweet soda-fountain drinks. Sugar is composed largely of carbon, and carbon is one of Nature’s greatest heat-makers.
Confine the diet largely to semi-acid fruits, fresh vegetables, green salads, milk, eggs, nuts, and a very limited quantity of bread and cereal products.
Cereal starch is the most difficult of all carbohydrate matter to digest.
Drink an abundance of pure water at meals and between meals. ”

“ Theoretically, gain or loss of carbon may mean gain or loss of either carbohydrate or fat, but practically stored-up carbon generally stands for accumulated fat; and, correspondingly, loss of carbon represents a withdrawal from the store of adipose tissue, since glycogen and sugar from a quantitative standpoint figure only slightly in these metabolic processes. When the body excretes more nitrogen than is taken in during a given period, there is only one interpretation possible, viz., that the body is losing proteid or flesh. ”

“ The facts above stated of the constant occurrence of glycogen in the muscular tissues, and its disappearance in part during muscular exercise, suggest at once the possibility of this substance being a fuel-material. We shall obtain light on this question from the facts regarding the influence of muscular exertion on the ratio of the volume of carbonic acid expired to that of the oxygen taken up. The three principal classes of foods consumed in the animal body are the fats, carbohydrates (starch, sugars, glycogen, etc.) , and nitrogenous substances. ”

“ Glucose, which is abundant in the juice of plants and fruits, and to a more or less degree in the blood of all animals (usually about 0.1%) occurs free in nature. This sugar is likewise obtained from many carbohydrates, either through the action of acids, or as the result of the digestive enzymes, and as such becomes the principal form in which the animal body utilizes the carbohydrates ingested. Under normal conditions the glucose in the blood is constantly being burned and replaced ”

“ How they act, whether simply as carriers of the products of protein digestion combined or uncombined, and how they give the material to the tissues is unknown. Carbohydrates are generally assumed simply to serve the purpose of yielding energy in their combustion to CO2 and H2O, and to act as protein sparers, 'i.e. they save the ingestion of large amounts of costly protein material as a source of energy. There may, however, be other activities in which the ingested sugars play a part, for instance, in the utilization of the nitrogen of proteins. ”