Carbohydrates - Their Place In The Daily Ration

The total food ration being kept near normal limits and fat and protein taken in proper amounts, the question of the proportion of carbohydrate obviously takes care of itself; but there are a few things in regard to this important fuel food that should be kept in mind.

The great bulk of food is carbohydrate, one of the seven great food classes. To this class belong starch, sugar and cellulose. Cellulose is not digested and serves merely as bulk, but when acted upon by strong acids it may be changed from cellulose to starch; from starch, through the stages of dextrin and maltose, to glucose the simple sugar which all digestible carbohydrate becomes before it is absorbed from the intestinal tract. All plant fibre is cellulose, the woody framework of trees, and even cotton. A story is told of a man who took a dirty shirt which had been worn by a tramp and, after washing it, put it through various chemical processes which changed it from the cellulose, which it really was, into glucose from which he made a delicious confection. However the digestive tract can not digest cellulose, so it passes through unchanged, simply serving as a broom to keep the bowel clean and as bulk upon which this muscular tube can exercise itself.

Starch

All sugar is at first starch. Unripe fruit contains starch rather than sugar, but as the fruit ripens the starch is changed to fruit sugar and this sugar is the simple form of carbohydrate which requires no digestion and is known by the names, glucose and dextrose. In vegetables starch is stored up in the plant, only a small portion of it becoming sugar. The carbohydrate of grains is mostly in the form of starch. Certain foods such as the Irish potato, polished rice, white bread contain a large proportion of carbohydrate in the form of starch and are often spoken of as starchy foods.

Sugar

The important difference in these forms of carbohydrate is that the starch must be changed into sugar during the process of digestion. Sugars may be classified as: Dextrin, Maltose, Sucrose, Glucose (or dextrose) and Laevu-lose (see footnote, page 74). The formation of dextrin is the first step in the process of the change of starch into sugar. (See page 12.) Maltose is the next step. It is formed in the malting of grains, during thorough mastication, and in the intestine where the process of starch digestion is completed by the action of the amylopsin of the pancreatic juice.

A Complex Sugar

Cane sugar or sucrose is the most complex sugar. It is formed in plants such as the sugar cane, the maple, and the sugar beet. In the process of digestion it is changed into the absorbable glucose.* Honey is a combination of cane sugar and fruit sugar, and because of its content of predigested fruit sugar it has an advantage as a food over the pure cane sugar.

Glycogen

The process of digestion completed, carbohydrate is absorbed in the form of glucose. It is then changed in the liver to a form called glycogen and is dealt out to the body as it is needed.

A Reserve Fuel

In the tissues the oxidation of sugar produces heat and energy, and it is eliminated as carbonic acid gas (C O2) and water (H2 O). Normally a certain amount of carbohydrate is changed over into fat and deposited in the tissues as reserve fuel. In this respect carbohydrate and fat differ from protein in that protein can not be stored as reserve for future use.

♦The chemical formula for starch is (C6 H10 O3)n, for dextrin (C6 H10 O5)n, for maltose C12 H22 O11. for cane sugar C12. H22 O11, for dextrose or glucose C6 H12 Cm. The change from starch into sugar may be represented by the following chemical equation: 2 (C6 H10 O5.) + Ho O - C12 N22 O11, or maltose. The change from maltose or from cane sugar, as the case may be, into the simple sugar glucose, is shown by the following: C12 H22 O11 (maltose) + H2O (water) = C6H12O26 (glucose) + C6H12O6 (glucose) or two molecules of glucose.

In cases of suboxidation due to lack of exercise or where the food intake is in excess of body demand, this storing of the carbohydrates in the form of fat may become excessive and obesity result.

Diabetes

Diabetes is an abnormal condition in which the oxidation of sugar is interfered with and sugar, instead of being used by the tissues, is dealt with by the blood as a foreign substance and, eliminated by the kidneys as glucose, is found as such in the urine. This metabolic disorder is not well understood, but is probably due to some abnormality in the internal secretions which govern the oxidation processes.

Starchy Food In Excess

One great harm resulting from an excess of food containing starch is in the extra tax placed upon the digestive tract because of the amount of digestion required by starch, mastication so often being incomplete. The increased length of digestion time may mean fermentation with the formation of irritating acids and gases which distend the bowel and prevent peristalsis, thus causing distress and flatulence.

This dietetic error is often a mistake made by vegetarians, who, not understanding how to balance their daily ration, take an excess of starch in their effort to get enough food. Starchy foods are often devitalized foods (See chapter IX (Vitamines)), another reason for a tendency toward sluggishness in the process of their digestion. Well cooked rice, however, because of the mechanical ease with which it mixes with the gastric fluids, is easily digested. As browned or dextrinized rice (See recipe 21) it becomes one of the most easily digested of foods.

The individual who has a good digestion may eat a large amount of starchy food and suffer no inconvenience, save perhaps an increase in avoirdupois. This increase in weight is, however, more liable to be the result when an excess of sugar or fat is taken.

Roughage

The amount of cellulose well tolerated by the digestive tract all depends on the inherent strength of its muscular wall. Some can take a large amount of bulky food; others find food containing much cellulose difficult of digestion. All, however, need a certain portion of cellulose or "roughage" to stimulate the bowel to its normal muscular activity. Much depends on the preparation of the food, the time spent in eating it, and the thoroughness with which it is masticated. With thorough mastication many of the bulkier foods ordinarily considered indigestible may be well taken and properly handled by the digestive tract.