What to eat and when

The work of the body never stops. If it is to be kept in thorough working order its tissues must be rebuilt as incessantly as they are torn down in the process of producing heat and energy. These chemical changes are called collectively metabolism.

They are divided into two groups: the chemical process of building up complex substances from simple ones is known as anabolism; the chemical process of oxidizing and breaking down the complex substances into simple ones, so that they are in a state to be excreted, is called catabolism. While the process of oxidation in catabolism is going on, heat and energy are set free. Many of the chemical changes in the body are catabolic in character. This work never ceases—even in sleep.

It is not enough that the proper foods be furnished the body in kind and quantity. The essential thing is that the system be kept in condition to assimilate the foods to its needs and to promptly eliminate the waste. Few people assimilate all of the foods eaten.

By assimilation is meant the process by which foodstuffs are made soluble and diffusible, so that they can pass into the blood; also, the metabolic activity by which the food is converted into cells and tissues.

Truly the body is a busy workshop. Think of the billions on billions of cells being formed and destroyed every instant in the liberation of heat and force! Think, also, of the necessity of perfect circulation to bring sufficient blood to the lungs, that it may gather the oxygen and carry it, without pausing for rest, to every tissue of the body! Even in sleep this stream continues incessantly.

There is also a great lesson here in the law of supply and demand. When the body is at mental or muscular work, the potential energy liberated leaves through muscle or brain, as energy, and is expressed in the result of the work. When the body is at rest, energy leaves it as heat (excepting such part as is necessary to carry on metabolism, circulation, etc.).

If much muscular energy is called for, a deep, full breath is instinctively drawn to supply the oxygen necessary for the added force.

If strong mental work is required, attention should be given to exercise and deep breathing, that the blood may carry off the waste liberated by brain activity. The difficulty is that in doing close mental work, the body is too frequently bent over a desk in such a manner as to restrict the action of the lungs; thus, the brain worker, in order to continue strong mental work, must often go into the open air, as he says, “to rest his brain,” but in reality to obtain the oxygen needed to put the waste, liberated by brain energy, in condition to be carried away. The supply of blood has been called on for the brain work; the poor circulation through the body has allowed an excess of carbon dioxid to accumulate and the condition of the body designated as “tired” has resulted. Until the necessary oxygen has been supplied, the brain and body are not balanced, not “rested.”

In its conversion into tissue, heat, energy, and waste, the importance of the chemical exceeds that of the mechanical action of digestion, absorption, assimilation, and elimination; yet the chemical changes are aided by the mechanical.

Nature provides against ignorance of the amount of supply necessary, by enabling the system to carry off a limited amount of surplus food above the bodily requirements. Her capacity in this regard is limited and varies with each individual. Therefore common sense is required in deciding for oneself the amount of food which will aid, and not hinder Nature in her processes.

Without doubt many eat more food than the system requires, and when it is overloaded they do not take the pains to burn up and eliminate the excess through exercise and oxygen.

On the other hand, this theory of overeating has been so long discussed that many have not eaten sufficient food and their bodies are undernourished. Many, also, from lack of exercise, hence lack of demand of the body for food, have supposed this lack of appetite to be Nature’s call “Enough”; inertia has resulted and waste remains in the body. They have failed to exercise sufficiently to create a demand for food. It is thus undernourished because sufficient new building material has not been supplied. The relief from this condition is exercise and deep breathing so that Nature removes the waste and calls for fresh building material.

Many others, through mental and physical activity, burn up much fuel and the result is the body does not store up sufficient fat for a reserve, or for beauty and comfort. The nerves require a certain amount of fat for their protection. People of this type should take a more full and sometimes a more varied diet, particularly more liquid, and should not fail in daily exercise and deep breathing.

Each individual should know, approximately, the chemical constituents and the proportion of these constituents in normal blood, because from the elements in the blood, the tissues are constructed. If certain elements are lacking, the foods containing these elements in largest proportions should be supplied until the blood no longer shows the deficiency. This is Nature’s method of correction. The variations in the blood can be known only by chemical analyses and until physicians have access to chemical laboratories the giving of drugs cannot be a science.

Each meal, or each day’s food, may not contain the amount of protein or of fuel ingredients necessary for that day’s work and resupply, but the body is continually storing material, and this reserve is constantly being drawn on to provide any element which may be lacking in that day’s supply. Thus, an excess or a deficiency one day may be adjusted the next. Healthful nourishment requires that the balance, as a whole, be kept and that a deficiency or oversupply be not continued for too long.

The distinct steps in anabolism and the effect of oxygen on assimilation are discussed in the following pages.

DIGESTION

Any discussion of the digestibility of foods must be general, because food which agrees with one may disagree with another, and a food which disagrees with one at a particular time may entirely agree with him at some other time according to the condition of his system. Therefore, before one passes on the adaptability of a food to his system, he should know that this food agrees or disagrees with him under various conditions.

The chances are that the food is right but that the attitude of mind and the condition of the body are abnormal.

The digestibility of food depends largely on the physical condition of the individual, because the amount of digestive juices poured into the alimentary canal is influenced by this condition, particularly by the condition of the nerves. If sufficient juices, in proper proportions, are not poured into the digestive tract, the foodstuffs are not made soluble for absorption.

Digestion is practically synonymous with solution—all solid foods must be reduced to a liquid state by means of the digestive juices and water before they can pass through the walls of the stomach and intestines and enter the blood.

Each individual should learn to like the foods containing the nutrient elements which experience and blood tests have shown to be lacking in his case.

Yet while it is true that in most cases the aversion to a particular food is largely mental, there are kinds of food which, to certain individuals, according to the chemical composition of the body, act as actual poisons, e. g., strawberries, cheese, or coffee.

The question of likes and of dislikes in foods, is largely habit, and one can learn to like almost any food, if one really has the desire to do so.

When the habit has been formed of discriminating too much in the food, of discarding this food or that, because at some time it has disagreed, due to the particular condition at the time, the mind approaches the table in a pessimistic attitude and the saliva and the gastric juices are retarded in their flow.

When one is exercising freely, so that the muscular and mucous coats of the digestive system are strong, the body will handle foods which, during sedentary habits, it would not digest.

Much indigestion is due to mental apathy. The mind often needs arousing to an interest in something.

Such an individual needs to know that one of the hardest things for the members of his family is to live day by day with one who maintains an attitude of mental depression, and he should stir himself for “his stomach’s sake,” as well as for the sake of his family, to a cheerful interest in something. He should let go his grudge and ride a hobby, if it is a cheerful one, and ride it hard.

It may be well, here, to trace, briefly, the progress of the food through the digestive tract and the action of the juices and the ferments on it.[5]

The food in the mouth is mixed with saliva, which begins the dissolution of the starches.

The saliva consists of about 99.5 per cent. water and 0.5 per cent. solids. The solids consist of ptyalin, sodium chlorid, sodium carbonate, mucus, and epithelium. Ptyalin, the most important of these, is the active digestive agent; the mucus lubricates the masticated food; the sodium carbonate insures the alkalinity of the food, and the water dissolves the food that the juices may more readily reach and act on each particle.

The starches are the only foods whose chemical digestion is begun in the mouth. They are first broken up by the ptyalin into dextrin and then into the more simple sugar, known as maltose.[6]

It is important that sufficient saliva be mixed with the food through mastication, because unless the digestion of the starches is begun by the saliva, either in the mouth or after it is swallowed, they are not acted on until they reach the small intestine, consequently their digestion is unduly delayed. The pancreatic juice must then do more than its normal work of digestion.

The saliva flows into the mouth, more or less, at all times, but more copiously during mastication.

The movement of the jaws in chewing incites its flow and when starches are not well digested, gum chewing, in moderation, though not a refined habit, is beneficial.

The evident purpose of the saliva when food is not present is to keep the lining of the mouth moist.

Salivary digestion is carried on in the stomach until the food becomes thoroughly mixed with the gastric juice, which, being acid, inhibits the action of the ptyalin.

The thorough and regular cleansing of the teeth is an important aid to digestion. Food products allowed to remain about the teeth ferment, rendering the mouth acid. When the mouth is acid, the alkaline saliva does not secrete in sufficient amount and the mouth is more or less dry.

The mouth is acid in rheumatism and allied conditions and the saliva may be thick and ropy so that it does not moisten the food properly. On the other hand the flow of saliva may be too free, the ptyalin is then too much diluted to promptly act on the food. This may result from overstimulation of the salivary glands occasioned by the excessive chewing of gum, or tobacco. These excesses also carry too much air into the stomach, resulting in flatulence.

The flow of saliva is controlled, largely, by nerves centering in the medulla oblongata. The sight of food, pleasingly served, or even the thought of food which one likes, will increase the flow. This is one instance of the control of thought over digestion, and the importance of forming the habit of cultivating a taste for all kinds of food is apparent. The stronger the relish for the food, and the more thoroughly it is masticated and mixed with the saliva, the more perfectly will the first step in digestion be accomplished.

Thorough mastication is important, not only because the chemical action on the starch molecules is facilitated by the softening and mixing with the saliva, but also because thorough mastication tends to prevent overeating—the appetite is more quickly satisfied when the food is well masticated.

Cool water encourages the flow of saliva and for this reason should be drunk before meals, particularly when digestion is weak. It may be taken at rest periods during the meal. (See page 31.)

The relation of the mouth and nasal passages to the digestive processes is seldom considered by the average individual. Their importance to the growing child is being recognized by the examination of school children which is now being made a part of the health program in many of our cities. Their importance to the adult is no less.

Food particles allowed to remain around the teeth, or in the cavities of decayed teeth, incite bacterial action. With the next meal these bacteria are swallowed and cause fermentation of the food, occasioning indigestion, and possibly, dyspepsia.

Decayed or missing teeth, swollen gums, or pyorrhea, interfere with proper mastication of food, hence it does not receive the thorough salivary moistening necessary; the starches pass practically unchanged into the stomach and small intestine, overburdening these organs.

Catarrh of the nasal passages, with the constant swallowing of germ-filled secretions, carries morbid products into the stomach, coating the glands with mucus, often infecting them; it may also occasion a catarrhal condition of that organ.

If, from any cause, the saliva becomes acid, dryness of the mouth results and desire for food is lessened or absent. Diseases of the salivary glands may render these necessary secretions unfit to perform their work.

In illness the mouth often drops open from weakness, producing the same condition of dryness. The mouth, in illness, is too often neglected by those in charge of the invalid.

Adenoids and enlarged turbinates in child or adult, narrowing the nasal passages and preventing the ingress of air, cause mouth breathing. The air dries the membranes and the tongue becomes swollen and cracks, interfering with proper mastication.

Adenoids should be removed, and any other condition which interferes with the proper function of the mouth should be remedied as soon as possible.

The mouth should be properly cleansed, the gums massaged, the teeth thoroughly brushed, back as well as front, defective teeth repaired or removed, abnormal growths eliminated, and the secretions kept abundant and healthy. Food well prepared in the mouth by thorough mastication satisfies hunger, renders more easy the work of the stomach and intestines, and aids in the general welfare of the system.

This too prevalent habit may aggravate the condition which it is supposed to cure. A slight indigestion appearing, gum is often chewed to cause a fuller flow of saliva to aid digestion. If gum-chewing is indulged in to excess, however, the muscular movements overstimulate the salivary glands, eventually weakening them. Overuse of the chewing muscles and overexcitation of the nerves fatigue them and cause them to weaken. The sticky gum, adhering to fillings in the teeth, loosens them and furnishes a lodging place for food particles and bacteria.

The excess of saliva may render the gastric juice alkaline, inhibiting its action. Excess of air swallowed with the saliva may cause flatulence or accumulation of gas in the stomach.

Lack of poise and nerve tension is increased by excessive gum-chewing, resulting in fatigue of the entire body. This lack of poise may be noted in any public assembly, as the “movies,” frequented by gum-chewers.

The habit, as generally practiced, is not an inspiring sight and should be discouraged.

Gum-chewing in moderation, for a few minutes after a meal, may not do harm, but its indiscriminate use is to be deplored. Thorough mastication of food will serve to supply the necessary saliva.

Exercise directed to the stomach and a more thorough circulation and elimination will do more for any digestive derangement than the excessive practice of chewing gum.

As the food enters the stomach, the gastric juice pours out from the mucous lining, very much as the saliva pours into the mouth. Like the saliva, it consists of 99.5 per cent. water and 0.5 per cent. solids. The solids of the gastric juice are pepsin, rennin, hydrochloric acid, and mucus.

The mucus serves to lubricate the food as in the saliva. It perhaps also aids to prevent the digestion of the mucous lining of the stomach.

The hydrochloric acid and the pepsin cause the principal chemical changes in the food while in the stomach. They act only on the proteins. The hydrochloric acid must be present before the pepsin can act, as only in an acid medium can pepsin dissolve the proteins. It is also of an antiseptic nature and hinders or prevents the decomposition of food.

The rennin ferment precipitates the casein.

The only digestion of starches in the stomach is that continued by the saliva.

Gastric juice begins to flow into the stomach soon after eating, but normally it is not secreted in sufficient quantity to supersede salivary digestion for from twenty to forty-five minutes.

The result of gastric digestion of proteins is their conversion, first, into albumin, then into proteoses, and, lastly, into peptone, which is protein in a more simple, soluble, and diffusible form. In the form of peptone, the proteins are in condition to be absorbed.

If the food has been properly cooked and masticated, gastric digestion will be completed in from one and one-half to three hours. If not properly cooked and masticated, the stomach digestion may continue from one to two hours longer. It should, however, be completed in three hours.

It will be seen that the evening meal is ordinarily digested before sleep, as one does not retire for from three to five hours after eating.

If, through imperfect mastication, or a disordered condition of the stomach, the digestion is not completed in about three hours, the food is likely to be retained in the stomach and by its weight may cause prolapsus of that organ if the supporting tissues are weak. Fermentation may ensue and give rise to gases which may cause acute distress.

Animal foods, which are readily digested, remain in the stomach for a shorter time. Meat, as a rule, is easily digested, because the digestive juices of the animal have converted the starches and sugars. The white meat of chicken is digested in a shorter time than the red or the dark meat.

Corn, beets, peas, beans, etc., take about three and a half hours to digest; baked potatoes about two and a half hours.

Raw vegetables and fruits remain about the same length of time as potatoes.

Sugar is usually absorbed within an hour.

The cereals, if well cooked, take but two hours.

Coarse or badly masticated food, tough meats, unripe fruits, and much fat hinder digestion.

Undigested food passing into the intestine may fail to be acted on there and will sometimes produce diarrhea.

Fluids leave the stomach more rapidly than solids. Seven ounces of water entirely leaves the stomach in one and one-half hours, seven ounces of boiled milk in about two hours. Water and buttermilk almost immediately begin to pass out of the stomach; milk begins to pass out in about fifteen minutes.

The flow of gastric juice, as the flow of saliva, is governed by the nerves; the sight, taste, and smell of food, and the attitude of mind toward it, to a certain extent, regulate its flow.

After the food has accumulated, during the progress of a meal, the stomach begins a series of wave-like movements called peristaltic waves.[7] These waves propel the food through the length of the stomach towards its lower opening, known as the pyloric orifice. During this process the food is thoroughly mixed with the gastric juice.

During the early stages of digestion of solids, the sphincter muscles of the pylorus keep the lower opening of the stomach closed, but, as digestion progresses, the pylorus gradually relaxes to let the digested, soluble portion of the food pass into the intestine. If the food still remains in a solid form, by reason of being improperly cooked or poorly masticated, as it touches the pylorus, these sphincter muscles, almost as if they were endowed with reasoning faculties, close, forcing the undigested mass back to be further acted on by the gastric juice—the solid mass is not allowed to pass until dissolved.

If the individual abuses the stomach and causes it to work overtime, it becomes exhausted and demands rest; it refuses to discharge the gastric juice in proper proportion; the peristaltic movements are weak; and food is not promptly or forcefully moved along the stomach and mixed with the gastric juice. This condition is termed indigestion.

The food passes from the stomach, through the pylorus into the small intestine. In this condition of partial digestion it is called chyme.

The first twelve inches of the small intestine is known as the duodenum. In the duodenum the food is acted on by the pancreatic juice, the bile, and the intestinal juices. These juices act on proteins, fats, and carbohydrates. The bile acts on the fats, while the pancreatic and intestinal juices act on the proteins and the carbohydrates. The starches, or dextrin, not fully digested by the saliva, are changed to maltose and glucose, while the trypsin from the pancreatic juice, together with the intestinal juices, change into peptone the protein not fully digested in the stomach. The pancreatic juice also digests the starch found in raw fruits and in such raw vegetables as radishes and lettuce.

Fats are almost entirely digested in the small intestine. The presence of fat stimulates the flow of pancreatic juice, which, in turn, stimulates the flow of bile. For this reason, in some conditions, if the liver is sluggish, fatty foods in moderation are desirable. When bile is not present in sufficient amount the fatty foods ferment and cause gases and foul odors.

The fats are absorbed almost entirely in the small intestine—mostly in the duodenum. Some of the fat may be absorbed directly without undergoing the process of emulsification. Some oils, as paraffin oil, are not absorbed at all but act only as a lubricant of the intestines.

When the food enters the intestine its reaction is acid. Mixed with the bile, pancreatic and intestinal juices, which are alkaline, its reaction becomes alkaline.

The pancreatic juice splits up the fats into glycerin and fatty acids and enables the bile to exert its important emulsifying power. The bile markedly aids this action of the pancreatic juice though it has no fat-splitting power in itself.

Steapsin, another ferment of the pancreatic juice, acts on both fats and carbohydrates in either an acid or alkaline medium.

The sodium in the bile unites with the fatty acid, forming a soap which coats the tiny particles of fat and emulsifies them. The bile thus aids in the absorption of the fats. It also lubricates the intestinal mass, facilitating its passage through the entire length of the intestines. Thus it is a very potent agent in regulating the bowel movements.

A diminution in the flow of bile quickly expresses itself in constipation.

Fat and protein stimulate the activity of the liver, while starches, if taken in excess, incline to overload it.

The food is forced along the intestinal tract by peristaltic or muscular relaxation and contraction waves, as in the stomach. As it is so forced, the nutrient elements, after being put into condition for absorption, are taken up through the villi of the intestinal walls by the portal veins and the lacteals of the submucous lining.

A larger proportion of food is digested and absorbed than was formerly supposed, and the excretions from the intestines are, in many cases, made up almost entirely of refuse, and of the catabolic waste of the system. In an ordinary mixed diet, it is stated that about ninety-two per cent. of the proteins, ninety-five per cent. of the fats, and ninety-seven per cent. of the carbohydrates are retained by the body.

In digestion, it is of the utmost importance that the muscular, mucous, and submucous coats, and the secreting glands of the stomach and intestines be kept thoroughly strong and active, that the digestive juices may be freely poured out, the nutriment be freely absorbed, and the food be moved along the digestive tract. The strength of any organ is gained through the nutriment in the blood; therefore, daily exercise, which calls the blood freely to these organs is imperative. Daily exercise should be directed to the vital organs. A walk for exercise is not sufficient.

The greater part of the food is absorbed through the intestines, yet some proteins which have been fully digested by the gastric juice, and certain fats, particularly the fats in milk, which are in a natural state of emulsion, may be absorbed through the walls of the stomach. However, the absorption through the stomach is small compared to that through the small intestine.

The small intestine is peculiarly fitted for absorption. Its mucous lining is thrown up into folds to furnish a larger surface for this purpose. The folds hold the food as it passes toward the large intestine, until the villi have the opportunity to absorb it.

These transverse folds of the intestinal walls are called valvulæ conniventes.

The villi are tiny finger-like projections of the mucous lining of the intestines, which stand out of the lining somewhat as the nap on plush. They have been called “sucking” villi, because during the movements of the intestines they seem to suck in the liquid food.

As soon as the foodstuffs—proteins, carbohydrates, and fats—are put in an absorbable state called chyle, they are very promptly taken up by the villi.

If for any reason the chyle remains unabsorbed, it is liable to be attacked by the bacteria always present in the intestines, and gases form.

The peptones, sugars, and saponified fats are rapidly absorbed, while the undigested portion, together with the unabsorbed water, the bile, mucus, and bacterial products, are passed through the ileocecal valve into the large intestine.

The mass passes up the ascending colon, on the right side of the abdomen, across the transverse, and down the descending colon, on the left side, losing, by absorption, the small amount of foodstuffs not absorbed in the stomach and small intestine. That the large intestine is to some extent adapted to absorption is shown by clinical experiments with patients who cannot retain food in the stomach, the food in such cases being given through rectal injections.

While water and salt are absorbed in both the stomach and small intestine, the larger part of the water passes into the large intestine, that it may assist the passage of the intestinal contents.

Water also stimulates peristaltic movements.

As the food is absorbed through the walls of the alimentary canal, it is picked up by the rootlets of the mesenteric veins and by the lymph channels—the latter through the abdominal cavity are called lacteals. Nearly all of the fats are absorbed through the lacteals. The whitish color given to the contents of the lacteals, by the saponified fats, gives rise to the term “lacteal.”

Nearly all of the proteins and sugars pass through the mesenteric veins and the portal veins to the liver. Here the sugars are at once attacked by the liver cells and built up into glycogen as described on pages 151 and 159. A small portion of the proteins, however, do not go to the liver, but are passed directly into the lymphatics and thus into the blood stream, where they are again carried to the liver, and the urea is separated.

To sum up, the larger part of the sugars, starches, proteins, and fats is absorbed through the small intestine, a small amount being absorbed in the stomach and a very little through the large intestine. While some water and salts are absorbed in the stomach and small intestine, these are largely absorbed in the large intestine.

It is economy to keep the digestive organs and the circulation and tissues strong, in order that all foods eaten may yield returns, instead of hampering the activity of the body.

The food which furnishes the most tissue-building substance and yields the most heat and energy, with the least refuse, is the economical food, provided it is varied enough to meet the psychical needs as well as the physical.

Whether or not a food is economical depends on the degree to which it stimulates the activity of the mind as well as the body. Preparation and serving here are as important as the material to be served.

Economy in food is a question into which many factors should enter. A cheap food is not always an economical food. Amount and keeping qualities, palatability, ripeness or unripeness, the age, habit, and occupation of the partakers, all have their share in the problem.

In the selection of food for any individual, the result to be gained from the food must be borne in mind. If one is doing heavy muscular work, more protein to rebuild tissue, as well as more carbohydrates and fats to produce energy, are required than if one’s habits of work are sedentary.

In mental work, in which the brain is continually active, proteins are required to resupply the brain tissue, but the fats and carbohydrates may be lessened. If the brain is sufficiently active to use all of the fuel in brain energy one does not accumulate fat.

In sedentary occupations, which do not call for hard and continuous mental activity, the carbohydrates and fats, if taken in excess, are stored within the system, clogging it and producing torpid liver, constipation, and obesity.

In a study of tables of food values, in making up a dietary, the question should be to provide the largest quantity of nutriment at the lowest cost, with due attention to palatability and variety.

In the selection of meats, for instance, while beef steak may cost twice as much as beef stew, it must be borne in mind that beefsteak contains very little waste, and that it contains a large proportion of albuminoids, or the tissue-building proteins, while, in beef stew, bone and connective tissue predominate. A large proportion of the proteins obtained from the beef stew are gelatinoids and extractives—not the tissue-building albuminoids. (See page 56.)

In comparing the cheaper and the more expensive cuts in the same kind of beefsteak, however, the cheaper cuts often yield quite as much nutriment as the more expensive ones. Round steak is just as nourishing as porterhouse and cheaper, if one considers the greater number of helpings derived from a pound of round steak than from a pound of porterhouse.

For the aged or the invalid, however, the question of preparation will determine the relative economy.