WE have discussed the question how to eat and what to eat; there remains the question of when to eat. English people, as a rule, eat four meals a day. The French are practically a two meal a day nation, eating a very light breakfast.
Of late years there has been a strong tendency on the part of American dieticians to advocate a reduction in the number of daily meals, the ideal aimed at being the establishing of the custom of two meals a day, with at least six hours intervening between them.
It may be asked whether appetite is not a safe guide to follow, and whether it is not the part of wisdom to follow personal inclination in the choice and quantity and number of meals. Does not a study of dietetic customs and habits definitely decide the essential rules of dietetics? While it is true that habits and customs are very strong factors in everybody’s life, yet it is also true that they are very unreliable guides. We are constantly acquiring new habits, and sloughing off old ones; and even the most deeply impressed of habits may be changed for others. And while the common customs of mankind would seem to indicate that three or four meals a day is the rule, at least among civilized nations, yet the facts are that the most primitive people take one meal a day, and the great majority of people in the world, as a rule, eat certainly less than three.
Physiological facts argue for the two meal plan, or else for very light and easily digested food, if an extra meal be taken.
Healthy digestion requires at least five hours for its completion, and one hour for rest before another meal is taken. This makes six hours necessary for the disposal of each meal. If food is taken at shorter intervals than this, when ordinary food is eaten, the stomach will be allowed no time for rest. Again, if a meal is taken before the preceding meal has been digested and has left the stomach, a portion remaining, one is likely to undergo fermentation, in spite of the preserving influence of the gastric juice; thus the whole mass of food will be rendered less fit for the nutrition of the body, and the stomach itself will be likely to suffer injury from the acids developed.
These facts make it plain why eating between meals is a gross breach of the requirements of good digestion. The habit of nibbling at confectionery, fruit, nuts, and other things between meals, is a positive cause of dyspepsia. No stomach can long endure such usage. There is a continual irritation of the mucous membrane of the stomach, and a continual excitation of the glands, which, in the long run, work great harm.
The same reasons which are advanced against the habit of eating between meals fit the case of irregularity of meals. Those who have regular duties, regular hours of work, should have regular meal hours. The human system is continually forming habits, and seems in a great degree dependent upon the performance of its functions in accordance with the habits that are formed. This fact is especially observed in respect to digestion. When meals are taken at regular times the stomach becomes accustomed to receiving food at those times, and is prepared for it. If meals are taken irregularly, the stomach is taken by surprise, so to speak, and is never in that state of rest in which it should be for the prompt and perfect performance of its functions. The habit which many business and professional men form, in the stress of their occupations, of allowing their meal hours to be intruded upon, at times depriving themselves of a meal, will undermine the best digestion in the long run. There is no physiologist who would not endorse the following words of Kellogg: “Every individual ought to consider the hour for meals a sacred one, not to be intruded upon under any ordinary circumstances. Eating is a matter of too momentous importance to be interrupted or delayed by ordinary matters of business or convenience. The habit of regularity in eating should be cultivated.”
The meal which most people would find it advantageous either to drop altogether, or to reduce in quantity, is supper. The physiological law which is now come to be recognized is, that the brain must be active to insure good digestion; and that the stomach must be empty to insure good sleep. That sense of drowsiness which so often follows a hearty meal is not a physiological condition; it is not evidence of a naturally sedative effect in eating; but is really an evidence of indigestion. Those who practice eating before retiring often sleep soundly until an hour or two after midnight, then awake, and find difficulty in getting to sleep again. This is due to irritation of the solar plexus set up by the labor of digesting under unfavorable conditions. The lack of appetite for breakfast after a late supper is evidence of the exhausted state of the stomach. Fruits and cereals are the ideal supper rather than the ideal breakfast—though good at any time!
It is nearly always the case that a hasty or over-hearty eater is also in the habit of drinking copiously of water or other fluids at his meals. He “washes his food down” instead of legitimately drinking. The body, of course, needs liquid, but, as a rule, meal times are not the times for the taking of this liquid supply; except for what is contained in the food itself. The hasty eater thus associates two great evils.
Liquid of any kind in large quantity is inimical to digestion, because it delays the action of the gastric juice, and weakens its digestive qualities, and also checks the secretion of saliva. In case the fluid taken is very hot, as tea, coffee, cocoa, or a considerable quantity of soup—it relaxes and weakens the stomach. On the other hand if it is very cold, it checks digestion by cooling the contents of the stomach, and reducing its temperature to a degree at which digestion cannot proceed. Even a small quantity of cold water, ice cream, or other very cold substance will create a serious disturbance if taken into a stomach where food is undergoing digestion. The process of digestion cannot be carried on at a temperature that is less than the body, which is about one hundred.
The old notions about the processes of digestion were chiefly drawn from the experiments of Dr. Beaumont made nearly a hundred years ago up in Northern Michigan, around Mackinac; with a Canadian hunter, Alexis St. Martin, as the subject. Most people have probably read of St. Martin and Beaumont in the physiologies they studied in their school days. Beaumont was a very capable physician, and a man of the truest scientific spirit. It happened that through an accident he was given an opportunity to make the most valuable contribution to the study of the stomach of man that so far had been furnished by any investigator. The hunter, St. Martin, had suffered a gunshot wound in his stomach, and Beaumont kept him alive for years with the wound open so that he might study the movements of the man’s interior organs. For the first time, here was a human body with a window in it, so to speak, and through this window the scientist patiently watched and studied for years. Of course, however, the window gave only a limited view of what was going on inside this particular house of life, and a great number of Beaumont’s ideas and theories have been proven erroneous; nevertheless, he obtained much important knowledge. When Dr. Beaumont peered through that curious window which he made in the stomach of Alexis St. Martin, he noticed that when the latter drank a glassful of water at the usual temperature of freshly drawn well water, the temperature of the food undergoing digestion fell immediately to 70. The process of digestion was checked absolutely and did not resume until the body had regained its proper temperature, which it did not do for more than half an hour.
Another way in which drinking at meals proves harmful is because of the fact that particles of food not thoroughly masticated are washed from the mouth into the stomach. If any drink at meals is taken at all, it should be a few minutes before eating. Of course, sipping of a little water will not be harmful, if care is taken not to sip at the time when food is in the mouth. It will be found, however, that unless the meal is composed of very dry foods, there will be little inclination to drink at meals. When, however, the food is rendered either fiery or irritating with spices, and other stimulating condiments, it is small wonder that there is an imperious demand for water or liquid of any kind to allay the irritation.
He who is really hungry, however, has no need of condiments, and usually small relish for them.
The old saying that hunger is the best sauce is one of those proverbs of the people which modern science is proving to be firmly established on truth. No sauce can equal appetite. Experiments by Professor Pawlow of St. Petersburg, Director of Department of Experimental Physiology in the Imperial Literary School of Medicine, have shown that there is a real “appetite juice” formed by the body when it is hungry.
Appetite, and hunger, are not synonymous terms with the mere habit-craving for food which most people consider to be either appetite or hunger. Real hunger, or appetite, only comes to the body when the body has earned it. There must be an expenditure of tissue, which the body requires to be repaired; or there must be a real need for energy to carry on work before the body will manifest its need for energy-supplying material. In other words, the body cares nothing about our likes or dislikes, our whims or our fancies, in the nature of food, save when it has a real need for food. Professor Chittenden demonstrated that most people simply eat the entire round of meals from mere habit. The disturbance when for any reason they miss one or two meals from the accustomed routine is simply the outcry of a habit and not the outcry of a real need. While Dr. Kellogg advises that no meal be missed, yet he also strongly advises us not to eat unless really hungry, merely drinking a little fruit juice or something of the kind at the meal hour in order to keep up the normal action of the digestive organs.
The digestive juice which is manufactured by the body when it is really hungry and food has been given to it has been shown by Pawlow and Hanecke to be the most important element in digestion. The chemical juices produced in the stomach and intestines while food is in them is of small importance and value compared with the juices that are formed while food is being chewed when the body has a good appetite or is really hungry.
This juice begins to flow at the very sight of food, and continues to from three to five minutes after beginning mastication. The production of juice in the stomach is stimulated by the contact of food with the mouth, and only during that contact; so it is obvious that the longer the food is held in the mouth, if it is held there in enjoyment, and the more completely it is chewed, so long as chewing is accompanied by taste, the more thoroughly are the flavors set free by the act of chewing, and the higher becomes the stimulating effect of these flavors upon the psychic centers which cause the appetite juice to flow into the stomach.
These facts prove the dependence of gastric digestion, or stomach digestion, upon mastication. Pawlow was experimenting with gastric juice when he hit upon this demonstration; and he has concluded that we cannot have gastric digestion at all well without thorough mouth digestion; that the complete mastication of food, in other words, is the thing necessary to prepare the stomach to receive the food. Thus, if you chew your food well, the food will be predigested in the mouth, and when it enters the stomach it will find already there waiting for it not only enough gastric juice to digest it, but just the particular kind of gastric juice that is needed.
Pawlow turned this discovery of his to a very practical use. He has a dozen or more healthy dogs which he calls his Dog Dairy. From these dogs he collects daily a quart or more of gastric juice, or appetite juice; and the dogs produce this large quantity without taking a particle of food into their stomachs. The juice is carefully filtered, and bottled and shipped all over the world to those physicians who are in touch with Pawlow and his work, and by them are administered to human patients. It is given to those patients who are deficient in gastric juice, and is used in very obstinate cases of indigestion.
Pawlow collects his juice by having openings made in the throat and in the stomachs of the dogs. When the dogs are hungry they are given food of kinds which they particularly like, and they are allowed to smell the odor and to become excited over the prospect of eating it before they are actually allowed to have it. With the first sight and odor of this food, the dogs begin to secrete the appetite juice, which flows from the opening made in their stomachs through tubes into receptacles. Then when they begin to eat their food, the food does not reach the stomach at all, but simply passes through the openings in the throat into a receptacle before the dog, and the dog can go on eating the same meal over and over again. They thus enjoy themselves thoroughly for a long time. When the appetite juice ceases to flow, the process of feeding them in this manner stops, and they are given a real meal.