Part 22

Is Alcohol a Food?--The question of the use of alcohol has been of late years a matter of absorbing interest and importance among physiologists. A few years ago Dr. Atwater performed a series of very careful experiments by means of the respiration calorimeter, to ascertain whether alcohol is of use to the body as food.[40] In these experiments the subjects were given, instead of their daily allotment of carbohydrates and fats, enough alcohol to supply the same amount of energy that these foods would have given. The amount was calculated to be about two and one half ounces per day, about as much as would be contained in a bottle of light wine.[41] This alcohol was administered in small doses six times during the day. Professor Atwater's results may be summed up briefly as follows:--

1. The alcohol administered was almost all oxidized in the body.

2. The potential energy in the alcohol was transformed into heat or muscular work.

3. The body did about as well with the rations including alcohol as it did without it.

Footnote 40: Alcohol is made up of carbon, oxygen, and hydrogen. It is very easily oxidized, but it cannot, as is shown by the chemical formula, be of use to the body in tissue building, because of its lack of nitrogen.

Footnote 41: Alcoholic beverages contain the following proportions of alcohol: beer, from 2 to 5 per cent; wine, from 10 to 20 per cent; liquors, from 30 to 70 per cent. Patent medicines frequently contain as high as 60 per cent alcohol. (See page 294.)

The committee of fifty eminent men appointed to report on the physiological aspects of the drink problem reported that a large number of scientific men state that they are in the habit of taking alcoholic liquor in small quantities, and many report that they do not _feel_ harm thereby. A number of scientists seem to agree that within limits alcohol may be a kind of food, although a very _poor_ food.

On the other hand, we know that although alcohol may technically be considered as a food, it is a very unsatisfactory food and, as the following statements show, it has an effect on the body tissues which foods do not have.

Professor Chittenden of Yale College, in discussing the food problem of alcohol, writes as follows:

"It is true that alcohol in moderate quantities may serve as a food, _i.e._ it can be oxidized with the liberation of heat. It may to some extent take the place of fat and carbohydrates, but it is not a perfect substitute for them, and for this reason alcohol has an action that cannot be ignored. It reduces liver oxidation. It therefore presents a dangerous side wholly wanting in carbohydrates and fat. The latter are simply burned up to carbonic acid and water or are transformed to glycogen and fat, but alcohol, although more easily oxidized, is at all times liable to obstruct, in a measure at least, the oxidative processes of the liver and probably of other tissues also, thereby throwing into the circulation bodies, such as uric acid, which are harmful to health, a fact which at once tends to draw a distinct line of demarcation between alcohol and the two non-nitrogenous foods, fat and carbohydrates. Another matter must be emphasized, and it is that the form in which alcohol is taken is of importance. Port wine, for instance, has more influence on the amount of uric acid secreted than an equivalent amount of alcohol has in some other form. To conclude: as an adjunct to the ordinary daily diet of the healthy man alcohol cannot be considered as playing the part of a true non-nitrogenous food."--Quoted in _American Journal of Inebriety_, Winter, 1906.

Effect of Alcohol on Living Matter.--If we examine raw white of egg, we find a protein which closely resembles protoplasm in its chemical composition; it is called albumen. Add to a little albumen in a test tube some 95 per cent alcohol and notice what happens. As soon as the alcohol touches the albumen the latter coagulates and becomes hard like boiled white of egg. Shake the alcohol with the albumen and the entire mass soon becomes a solid. This is because the alcohol draws the water out of the albumen. It has been shown that albumen is somewhat like protoplasm in structure and chemical composition. Strong alcohol acts in a similar manner on living matter when it is absorbed by the living body cells. It draws water from them and hardens them. It has a chemical and physical action upon living matter.

Alcohol a Poison.--But alcohol is also in certain quantities a poison. _A commonly accepted definition of a poison is that it is any substance which, when taken into the body, tends to cause serious detriment to health, or the death of the organism._ That alcohol may do this is well known by scientists.

It is a matter of common knowledge that alcohol taken in small quantities does not do any _apparent_ harm. But if we examine the vital records of life insurance companies, we find a large number of deaths directly due to alcohol and a still greater number due in part to its use. In the United States every year there are a third more deaths from alcoholism and cirrhosis of the liver (a disease _directly_ caused by alcohol) than there are from typhoid fever. The poisonous effect is not found in small doses, but it ultimately shows its harmful effect. Hardening of the arteries, an old-age disease, is rapidly becoming in this country a disease of the middle aged. From it there is no escape. It is chiefly caused by the cumulative effect of alcohol. The diagram following, compiled by two English life insurance companies that insure moderate drinkers and abstainers, shows the death rate to be considerably higher among those who use alcohol.

Dr. Kellogg, the founder of the famous Battle Creek Sanitarium, points out that strychnine, quinine, and many other drugs are oxidized in the body but surely cannot be called foods. The following reasons for not considering alcohol a food are taken from his writings:--

"1. A habitual user of alcohol has an intense craving for his accustomed dram. Without it he is entirely unfitted for business. One never experiences such an insane craving for bread, potatoes, or any other particular article of food.

"2. By continuous use the body acquires a tolerance for alcohol. That is, the amount which may be imbibed and the amount required to produce the characteristic effects first experienced gradually increase until very great quantities are sometimes required to satisfy the craving which its habitual use often produces. This is never the case with true foods.... Alcohol behaves in this regard just as does opium or any other drug. It has no resemblance to a food.

"3. When alcohol is withdrawn from a person who has been accustomed to its daily use, most distressing effects are experienced.... Who ever saw a man's hand trembling or his nervous system unstrung because he could not get a potato or a piece of cornbread for breakfast? In this respect, also, alcohol behaves like opium, cocaine, or any other enslaving drug.

"4. Alcohol lessens the appreciation and the value of brain and nerve activity, while food reenforces nervous and mental energy.

"5. Alcohol as a protoplasmic poison lessens muscular power, whereas food increases energy and endurance.

"6. Alcohol lessens the power to endure cold. This is true to such a marked degree that its use by persons accompanying Arctic expeditions is absolutely prohibited. Food, on the other hand, increases ability to endure cold. The temperature after taking food is raised. After taking alcohol, the temperature, as shown by the thermometer, is lowered.

"7. Alcohol cannot be stored in the body for future use, whereas all food substances can be so stored.

"8. Food burns slowly in the body, as it is required to satisfy the body's needs. Alcohol is readily oxidized and eliminated, the same as any other oxidizable drug."

The Use of Tobacco.--A well-known authority defines a narcotic as a substance "_which directly induces sleep, blunts the senses, and, in large amounts, produces complete insensibility_." Tobacco, opium, chloral, and cocaine are examples of narcotics. Tobacco owes its narcotic influence to a strong poison known as nicotine. Its use in killing insect parasites on plants is well known. In experiments with jellyfish and other lowly organized animals, the author has found as small a per cent as one part of nicotine to one hundred thousand parts of sea water to be sufficient to profoundly affect an animal placed within it. The illustration here given shows the effect of nicotine upon a fish, one of the vertebrate animals. Nicotine in a pure form is so powerful a poison that two or three drops would be sufficient to cause the death of a man by its action upon the nervous system, especially the nerves controlling the beating of the heart. This action is well known among boys training for athletic contests. The heart is affected; boys become "short-winded" as a result of the action on the heart. It has been demonstrated that tobacco has, too, an important effect on muscular development. The stunted appearance of the young smoker is well known.

Use and Abuse of Drugs.--The American people are addicted to the use of drugs, and especially patent medicines. A glance at the street-car advertisements shows this. Most of the medicines advertised contain alcohol in greater quantity than beer or wine, and many of them have opium, morphine, or cocaine in their composition. Paregoric and laudanum, medicines sometimes given to young children, are examples of dangerous drugs that contain opium. Dr. George D. Haggard of Minneapolis has shown by many analyses that a large number of the so-called "malts," "malt extracts," and "tonics," including several of the best known and most advertised on the market, are simply disguised beers and, frequently, very poor beers at that. These drugs, in addition to being harmful, affect the person using them in such a manner that he soon feels the need for the drug. Thus the drug habit is formed,--a condition which has wrecked thousands of lives. A number of articles on patent medicines recently appeared in a leading magazine and have been collected and published under the title of _The Great American Fraud_. In this booklet the author points out a number of different kinds of "cures" and patent medicines. The most dangerous are those headache or neuralgia cures containing _acetanilid_. This drug is a heart depresser and should not be used without medical advice. Another drug which is responsible for habit formation is _cocaine_. This is often found in catarrh or other cures. Alcohol is the basis of all tonics or "bracers." Every boy and girl should read this booklet so as to be forearmed against evils of the sort just described.

REFERENCE READING ON FOODS

Hunter, _Laboratory Problems in Civic Biology._ American Book Company. Allen, _Civics and Health._ Ginn and Company. Bulletin 13, American School of Home Economics, Chicago. Cornell University Reading Course, Buls. 6 and 7, _Human Nutrition._ Davison, _The Human Body and Health._ American Book Company. Jordan, _The Principles of Human Nutrition._ The Macmillan Company. Kehler, L. F., _Habit-forming Agents._ Farmers' Bulletin 393, U. S. Dept. of Agri. Lusk, _Science and Nutrition._ W. B. Saunders Company. Norton, _Foods and Dietetics._ American School of Home Economics. Olsen, _Pure Foods._ Ginn and Company. Sharpe, _A Laboratory Manual for the Solution of Problems in Biology,_ pp. 226-240. American Book Company. Stiles, _Nutritional Physiology._ W. B. Saunders Company. _The Great American Fraud._ American Medical Association, Chicago. _The Propaganda for Reform in Proprietary Medicines._ Am. Medical Association. Farmers' Bulletin: numbers 23, 34, 42, 85, 93, 121, 128, 132, 142, 182, 249, 295, 298. Reprint from Yearbook, 1901, Atwater, _Dietaries in Public Institutions._ Reprint from Yearbook, 1902, Milner, _Cost of Food related to its Nutritive Value._ Experiment Station, Circular 46, Langworthy, _Functions and Uses of Food._

XX. DIGESTION AND ABSORPTION

_Problems.--To determine where digestion takes place by examining_:-- _(a) The functions of glands._ -(b) The work done in the mouth._ -(c) The work done in the stomach._ -(d) The work done in the small intestine._ -(e) The function of the liver._ _To discover the absorbing apparatus and how it is used._

LABORATORY SUGGESTIONS

_Demonstration of food tube of man_ (manikin).--Comparison with food tube of frog. Drawing (comparative) of food tube and digestive glands of frog and man. _Demonstration of simple gland._--(Microscopic preparation.) _Home experiment and laboratory demonstration._--The digestion of starch by saliva. Conditions favorable and unfavorable. _Demonstration experiment._--The digestion of proteins with artificial gastric juice. Conditions favorable and unfavorable. _Demonstration._--An emulsion as seen under the compound microscope. _Demonstration._--Emulsification of fats with artificial pancreatic fluid. Digestion of starch and protein with artificial pancreatic fluid. _Demonstration_ of "tripe" to show increase of surface of digestive tube. _Laboratory or home exercise._--Make a table showing the changes produced upon food substances by each digestive fluid, the reaction (acid or alkaline) of the fluid, when the fluid acts, and what results from its action.

Purpose of Digestion.--We have learned that starch and protein food of plants are formed in the leaves. A plant, however, is unable to make use of the food in this condition. Before it can be transported from one part of the plant body to another, it is changed into a soluble form. In this state it can be passed from cell to cell by the process of osmosis. Much the same condition exists in animals. In order that food may be of use to man, it must be changed into a state that will allow of its passage in a soluble form through the walls of the alimentary canal, or food tube. This is done by the enzymes which cause digestion. It will be the purpose of this chapter to discover where and how digestion takes place in our own body.

Alimentary Canal.--In all vertebrate animals, including man, food is taken in the mouth and passed through a _food tube_ in which it is digested. This tube is composed of different portions, named, respectively, as we pass from the _mouth_ downward, the _gullet_, _stomach_, _small_ and _large intestine_, and _rectum_.

Comparison of Food Tube of a Frog and Man.--If we compare the food tube of a dissected frog with the food tube of man (as shown by a manikin or chart), we find part for part they are much the same. But we notice that the intestines of man, both small and large, are relatively longer than in the frog. We also notice in man the body cavity or space in which the internal organs rest is divided in two parts by a wall of muscle, the _diaphragm_, which separates the heart and lungs from the other internal organs. In the frog no muscular diaphragm exists. In the frog we can see plainly the silvery transparent _mesentery_ or double fold of the lining of the body cavity in which the organs of digestion are suspended. Numerous blood vessels can be found especially in the walls of the food tube.

Glands.--In addition to the alimentary canal proper, we find a number of _digestive glands_, varying in size and position, connected with the canal.

What a Gland Does. Enzymes.--In man there are the saliva gland of the mouth, the gastric glands of the stomach, the pancreas and liver, the two latter connected with the small intestine, and the intestinal glands in the walls of the intestine. Besides glands which aid in digestion there are several others of which we will speak later. As we have already learned, a gland is a collection of cells which takes up material from within the body and manufactures from it something which is later poured out as a secretion. An example of a gland in plants is found in the nectar-secreting cells of a flower.

Certain substances, called _enzymes_, formed by glands cause the digestion of food. The enzymes secreted by the cells of the glands and poured out into the food tube act upon insoluble foods so as to change them to a soluble form. They are the product of the activity of the cell, although they are not themselves alive. We do not know much about enzymes themselves, but we can observe what they do. Some enzymes render soluble different foods, others work in the blood, still others probably act within any cell of the body as an aid to oxidation, when work is done. Enzymes are very sensitive to changes in temperature and to the degree of _acidity_ or _alkalinity_[42] of the material in which they act. We will find that the enzymes found in glands in the mouth will not act long in the stomach because of the change from an alkaline surrounding in the mouth to that of an acid in the stomach. Enzymes seem to be able to work indefinitely, providing the surroundings are favorable. A small amount of digestive fluid, if it had long enough to work, could therefore digest an indefinite amount of food.

Footnote 42: The teacher should explain the meaning of these terms.

Gland Structure.--The entire inner surface of the food tube is covered with a soft lining of _mucous membrane_. This is always moist because certain cells, called _mucus cells_, empty out their contents into the food tube, thus lubricating its inner surface. When a large number of cells which have the power to secrete fluids are collected together, the surface of the food tube may become indented at this point to form a pitlike _gland_. Often such depressions are branched, thus giving a greater secreting surface, as is seen in the figure on page 298. The cells of the gland are always supplied with blood vessels and nerves, for the secretions of the glands are under the control of the nervous system.

How a Gland Secretes.--We must therefore imagine that as the blood goes to the cells of a gland it there loses some substances which the gland cells take out and make over into the particular enzyme that they are called upon to manufacture. Under certain conditions, such as the sight or smell of food, or even the desire for it, the activity of the gland is stimulated. It then pours out its secretion containing the digestive enzyme. Thus a gland does its work.

Salivary Glands.--We are all familiar with the substance called _saliva_ which acts as a lubricant in the mouth. Saliva is manufactured in the cells of three pairs of glands which empty into the mouth, and which are called, according to their position, the _parotid_ (beside the ear), the _submaxillary_ (under the jawbone), and the _sublingual_ (under the tongue).

Digestion of Starch.--If we collect some saliva in a test tube, add to it a little starch paste, place the tube containing the mixture for a few minutes in tepid water, and then test with Fehling's solution, we shall find grape sugar present. Careful tests of the starch paste and of the saliva made separately will usually show no grape sugar in either.

If another test be made for grape sugar, in a test tube containing starch paste, saliva, and a few drops of any weak acid, the starch will be found not to have changed. The digestion or change of starch to grape sugar is caused by the presence in the saliva of an _enzyme_, or _digestive ferment_. You will remember that starch in the growing corn grain was changed to grape sugar by an enzyme called _diastase_. Here a similar action is caused by an enzyme called _ptyalin_. This ferment acts _only_ in an alkaline medium at about the temperature of the body.

Mouth Cavity in Man.--In our study of a frog we find that the mouth cavity has two unpaired and four paired tubes leading from it. These are (_a_) the _gullet_ or food tube, (_b_) the _windpipe_ (in the frog opening through the _glottis_), (_c_) the paired nostril holes (_posterior nares_), (_d_) the paired _Eustachian tubes_, leading to the ear. All of these openings are found in man.

In man the mouth cavity, and all internal surfaces of the food tube, are lined with a _mucous membrane_. The _mucus_ secreted from gland cells in this lining makes a slippery surface so that the food may slip down easily. The roof of the mouth is formed in front by a plate of bone called the _hard palate_, and a softer continuation to the back of the mouth, the _soft palate_. These separate the nose cavity from that of the mouth proper. The part of the space back of the soft palate is called the _pharynx_, or throat cavity. From the pharynx lead off the _gullet_ and _windpipe_, the former back of the latter. The lower part of the mouth cavity is occupied by a muscular tongue. Examination of its surface with a looking-glass shows it to be almost covered in places by tiny projections called _papillae_. These papillae contain organs known as _taste buds_, the sensory endings of which determine the taste of substances. The tongue is used in moving food about in the mouth, and in starting it on its way to the gullet; it also plays an important part in speaking.