If we desire to derive benefit from what we eat in order to keep the body in good condition, and thus successfully resist the onslaught of old age, we must possess a good digestion and be able to make use of our gastric juice. Without this secretion all, or the greater part, of what we eat will remain undigested in the stomach and intestines, and by its stagnation produce much disturbance and lessen the vitality of these important organs. Everything, therefore, depends upon being provided with an adequate supply of gastric juice. There are two ways of aiding this: First, by the direct action of the food on the walls of the stomach. Second, by various means which act on the nervous system that governs the glands of the stomach and provokes their secretion. As by the first means only a small amount of gastric juice is secreted, we will deal with the second.
The nerves of the gastric glands can be stimulated by various agencies which influence the central nervous system, and thus provoke appetite; for instance, sight, for we know of old how the sight of tasty dishes provokes our appetite. Professor Pawlow, of St. Petersburg, has shown by experiments on dogs, in whose stomachs he had made a fistula, that merely showing them a piece of meat was sufficient to cause them to secrete a large quantity of stomach juice. Umber has also shown on man that optic influence was able to produce the secretion of gastric juice.
In addition to sight, smell produces similar results. Professor Bickel,[305] of Berlin, has experimented on a girl of 23, who, after an injury from caustic potash, had to have a fistulous opening made into her stomach, her œsophagus being completely strictured. By holding steaming hot soup under her nose he caused the secretion of a clear stomach juice to run through the open fistula.
The secretion of the stomach juice can also be produced by the sense of taste. Professor Bickel showed this in the above case by placing on the girl’s tongue a solution of sugar, and again of salt, and there followed each time a secretion of stomach juice.
Pawlow has also proved this by ingenious experiments on dogs. After making a fistula in their œsophagus he gave them pieces of meat to eat, which, on being swallowed, fell out again by the open œsophagus, so that they never reached the stomach; and yet the taste of the meat and chewing were sufficient to cause the production of a large amount of gastric juice.
Thus the secretion of the gastric juice is under nervous influence. But if pleasant nervous impulses are able to promote its secretion, on the other hand, as shown by the observations of Beaumont, and also of Sommerfeld on men, disagreeable impressions are able to check it. Bickel and Sasaki have also observed this to have occurred in persons who have been in a state of anger, which coincides with our own observations that when we are in a depressed mental condition, or when we receive disagreeable news, we often lose our appetite. If, therefore, we want to eat with relish we must put aside all mental pre-occupation and worry, and go to the table in a cheerful mood. Persons of a melancholy temperament seldom have an appetite, and in melancholia there is often a refusal to eat, so that nourishment has to be maintained artificially.
When any one has been working in the open air all day and is of a cheerful disposition, he will not need anything appetizing to make him eat. By his work he has digested his food easily, his body craves for more to keep up his energy, and his empty stomach requires to be filled; he will be hungry and have a good appetite without any artificial stimulus.
But it is a different thing with ladies who sit all day long in their rooms, or with men who sit all day at their office desks. Such persons very often need an artificial stimulus for a good appetite and sufficient gastric juice. We must then resort to small artifices to induce these. A snow white table cloth, beautiful service, choice fruit in artistic vases, wearing clean linen and evening dress, and having agreeable society and possibly music at dinner, will, perhaps, sufficiently act on the different senses to produce appetite and a free secretion of the gastric juice.
In certain restaurants we often see an open buffet with the choicest dishes displayed, from which we can select our meal; and this certainly acts as an appetizer. In certain countries, also, it is the custom to take before dinner little hors d’œuvres or delicacies, like the Zakuski in Russia, or the smörgasbord in Sweden, which certainly serve to enhance the appetite.
Those whose appetite needs stimulation may receive benefit from meat extracts, such as bouillon, before dinner. These extracts are some of the few things which can produce a sufficient secretion in the stomach directly, without the intervention of appetite, as has been shown by the experiments of many authorities. Such an appetizer would not, however, be advisable, because bouillon, containing extractive substances, is more injurious than meat if taken often and in large quantities.
For such as have no appetite it may be of advantage to wash the tongue before meals with a solution of salt; this, to a certain extent, will also cleanse a coated tongue, with which a good appetite is not easily attained; and at the same time, according to Bickel’s above-mentioned experiment, it may provoke a secretion of stomach juice. Vinegar and water will have the same effect as the saline wash. A coated tongue should always be cleansed before meals, for when the papillæ of taste are covered, the direct action of the food on them may be prevented.
Just before dinner, and for an hour after it, no mental work should be done; and it is often better to open a letter after than before dinner, so as not to spoil the appetite. A short walk in the fresh air before dining will also be an appetizer. We have personally noticed a diminution in appetite on those days when no exercise was taken.
Much depends on the way the meals are served. Above all things food must be pleasant to the eye and to the palate, and it is the great art of the cook to fulfill this. The greatest possible cleanliness is paramount, for with many people the sight of a dirty cloth or napkin is able to kill all appetite and check the secretion of gastric juice.
Reading while eating is contrary to the above indications, unless perhaps it be something humorous, like Mark Twain’s “Adventures of Huckleberry Finn,” for instance. If we have the chance of choosing our neighbors at the dinner table let us rather sit next some one having the characteristics of Mark Twain than an undertaker or one who talks business.
Besides the gastric juice the saliva also plays a very important rôle, as it contains a valuable ferment which facilitates the digestion of starch into sugar: the diastatic ferment. In order to have a good supply of saliva the food must be kept longer on the tongue, as the flow of saliva is best induced by the stimulation of the nerves of taste; so we must masticate longer, and move the food between the teeth and on the tongue for as long a time as possible, so that it will act on the nerves of taste.
The secretion of the salivary glands under nervous influence is actuated in the same way as is that of the gastric juice. It is powerfully influenced by psychical impressions; for instance, by impulses coming from sight to the nervous centers and thence to the salivary glands, as can easily be seen by daily observation. If we offer a hungry dog a sausage we shall all witness an abundant flow of saliva, and the same may also be seen in man, and the German saying, “das wasser läuft im Munde zusammen,” may be literally true.
The secretion of saliva can be provoked by much the same agencies as that of the stomach juice, but above all by mastication. This has the greatest effect on the flow of saliva, especially when accompanied by good appetite; in fact, we may say good appetite provokes the flow of saliva and mastication maintains it for a long time. We are thus able, by abundant salivation, to aid digestion wonderfully, especially with regard to starchy food, as the diastatic ferment of the saliva assists in transforming starch into sugar; otherwise such material would be rather difficult to digest, only depending then on the pancreatic and, perhaps, intestinal ferments. Another great advantage of thorough mastication is that the food reaches the stomach in the smallest possible pieces, perhaps in liquid form, and thus the stomach juice can reach it freely from all sides, whereby digestion is greatly facilitated.
Not only the digestion in the stomach, but also the absorption of food transformed into a liquid from the intestines is much assisted by thorough mastication; while, as the result of insufficient mastication, as with fast eaters, the food may cause much greater work to the walls of the stomach. Being much less absorbed from the intestine it may irritate it as a foreign body until expelled by greater efforts of the intestinal walls. Long-lasting gastric and intestinal catarrhs may result from insufficient mastication.
The great advantage of methodical long mastication has been shown by Harry Campbell,[306] Horace Fletcher,[307] and Van Sommeren, of Venice. According to their recommendation it would be necessary to masticate food until it has almost lost its taste. It certainly requires long practice, especially in the case of fast eaters, to acquire the habit of prolonged mastication, for nothing is so difficult as to give up habits indulged in since childhood. Fast eating is not only injurious to health, but if indulged in in company, it is a breach of good manners.
The authorities on thorough mastication also claim that by so doing they are able to do with less food, which is the more readily to be believed, as they are able to digest and absorb everything better, their food leaves less residue, and they profit more by what they eat than do fast eaters and bad masticators.
Good mastication means also good exercise for the teeth, the good condition of which is of the utmost importance for a healthy digestion just as it is important for all other organs of the body. When we eat fast we are inclined to wash down the imperfectly masticated food by large quantities of water, which may be prejudicial, as we are thus too freely diluting the contents of the stomach. Many women abstain from drinking at their meals for fear of getting fat, which is an erroneous idea, as Prof. Van Noorden has shown that this cannot produce obesity.[308] On the other hand, not drinking during meals may lead to bad results. We are accustomed to take most of the water we drink with our meals; not taking any at meals may largely decrease the amount of fluid in the body, which has many bad effects. As shown by Pawlow, and also by Bickel, more stomach juice is secreted when the body contains more fluid. Then drinking a certain amount of water at meals may assist in the absorption of the food. There is also the great advantage that by the aid of fluids the end-products of nitrogenous matters, which have toxic actions, may be more easily eliminated from the body than with a dry diet. We believe it is preferable to take even an excess of water, than none at all, with meals, and there are many people who have no appetite unless they drink while eating.
The question whether after meals we should rest or take exercise must be answered individually; those suffering from obesity or other disorders of metabolism, like gout or diabetes, had better take some form of exercise after a meal, while weak persons should rest. In general, a short walk after meals, and then remaining quiet for an hour, will prove to be best; but mental occupation for at least an hour after meals should be strictly prohibited.
The time for meals should be when we are hungry, as we should never eat at other times for fear of not being able to digest well, owing to the absence of stomach juice. It is essential to take our meals every day at the same time; our stomach is of such a clock-like mechanism that it best indicates the hour for meals. If well disciplined it will secrete its gastric juice every day at the same hour. If possible we should always eat in company, for then we will eat slower, masticate better, and, if the company is jovial, probably secrete more gastric juice.
Just as after meals, so also before them, any strenuous exercise should be forbidden. A little exercise may promote the gastric digestive secretions; but if we become tired from much exercise, then certainly not much and sometimes no gastric juice will be secreted; then meat extracts, bouillon, or soup will be necessary for obtaining an appetite. Some people eat too much bread, which may cause overwork for the stomach, as to digest bread gives it more work than does other food. It has been found that the albuminous parts of bread require five times more ferments and pepsin of the stomach than does meat; besides which, as we have found in many of our patients, there is nothing that causes an acid stomach so often as does too much bread, especially in nervous people.
The most digestible food for most stomachs is meat, if it does not contain much connective tissue. Meat sauces and bouillon are excellent appetizers. However, such nourishment at every meal has its inconveniences, on which we will enlarge in another chapter. It is most desirable only to take meat once a day—at dinner.
The albumin in meat is much easier to digest than that in vegetables; to digest the latter, particularly potatoes, cabbage, etc., we need to have a thoroughly good stomach. Fat dishes are able to diminish the quantity of stomach juice, and fatty potatoes or other vegetables with much fat, demand sound stomachs, in the same way as does rich pastry. Butter is an easily digested fat if it is fresh, but certainly not when it contains free fatty acids.
Besides meat, cereals, such as are taken in America at breakfast, especially when finely ground and taken in the form of flour, are most easily digested. It is an excellent American custom to commence breakfast with grape-fruit, which is somewhat astringent and very refreshing; but to begin breakfast with an apple or a pear is the greatest possible offense to a normal stomach, and occurs only because of the lack of a thorough knowledge of the physiology of the stomach.