Most of us have experienced a feeling of heaviness after a dinner consisting of rich meat, and not infrequently there is also a sensation of drowsiness after it, which is not easy to overcome. The first may be due to the difficulty of digestion; but we may not experience this after taking even twice as much carbohydrate and green vegetable food. We know, from the observations on food already referred to, that meat is far more digestible, unless it contains much connective tissue and sinewy matter, than the majority of cereals and green vegetables, and especially fruit; and yet after a dinner of the latter we will not feel so heavy as after a meal in which we have taken a smaller amount of food, but of which the greater part was meat.
This feeling of heaviness can, therefore, not be attributed to difficulty of digestion, and as there is, at the same time, a greater disinclination to work and a feeling of sleepiness after a meal with much meat than after one of vegetables alone, or of milk and vegetables, meat must, undoubtedly, have a more deleterious effect upon the central nervous system than have other kinds of food.
That this mere clinical observation is not fallacious is also shown by the fact that after eating much meat nervous disorders are far more frequent; and we find many more instances of neurasthenia and hysteria among eaters of much meat than among vegetarians; and in the treatment of many nervous disorders far better results are obtained after excluding meat from the diet.
It is noticeable in a marked degree in Graves’s disease, and also in myxœdema, that patients suffering from them will not improve with meat, and after partaking of it their symptoms are aggravated. This is only natural, as these diseases are caused by changes in the thyroid gland, to which we have referred in Chapter II, where we have also shown that this gland undergoes changes through an overabundance of meat. We have there mentioned the very interesting experiments of Leo Breisacher, of Detroit, and of Blum, of Frankfort, and others. But we would wish to remark here that it has been demonstrated by the experiments of Chalmers Watson, of Edinburgh, that when certain animals, such as fowls, eat much meat to the exclusion of all other kinds of food, they present great enlargement of the follicles of the thyroid gland, and that rats, kept on the same diet, exhibit even a degeneration of the gland, which can even go to the extent of presenting the clinical picture of Graves’s disease. Not only the thyroid, but the other ductless glands also, have been found altered after an exclusive meat diet. Forsyth[276] found also an enlargement of the follicles of the pituitary body in birds of prey, and Houssaye[277] found that chickens lost their fertility after such a diet, which affected their ovaries.
There are numerous clinical and anatomo-pathological evidences to show that the other ductless glands also—that is, the glands with internal secretion, such as the liver, kidneys, and even also the pancreas—are altered by an abundance of meat food if long continued.
We have already dwelt on the fact that the liver has the function of destroying the harmful products that are formed by the decomposition of meat food. Thus the more meat we eat the more work is thrown on the liver, which may first become hyperæmic, but, through the continuation of the harmful agency more deleterious conditions may develop. Every physician can observe daily, as we have, that when patients suffering from disorders of the liver take meat, they gradually get worse, but when they give up meat they soon get better. If, therefore, we desire to retain our vitality for a long time, it is best for us not to take too much meat.
In the same way the kidneys can also be kept in good condition if too much meat be not taken. These eliminate the end-products of meat food, and the more of such products that pass through the kidneys, the more of them are taken from the blood and excreted by means of the fine epithelia of the kidney tubules, and thus the more is the work done by these organs; and we have mentioned that any overwork of an organ may be followed by its exhaustion. As a consequence of eating meat sometimes very harmful products pass through the kidneys, especially in the case of preserved, strongly seasoned, or spiced meat, for such preserved food may contain disease germs, ptomaine bodies, mineral poisons, etc. But even the passage of normal end-products of meaty food—for example, if urea be continually passed for years in large quantities—can produce serious alterations. Many authorities, such as Dr. James Tyson, of Philadelphia, who is well known by his works on the kidneys, attribute to the very frequent taking of such food many cases of interstitial nephritis; and nearly all such authorities, including Senator, of Berlin, prohibit the use of meat in most of the disorders of the kidneys. But we have already referred to the danger of such a diet to the liver and kidneys, and it is only because of the importance of the subject that we have again referred to the matter.
There is some clinical evidence in favor of the opinion that the pancreas may also be altered by an abundant meat diet. We know that when this organ is diseased we may discover a quantity of unabsorbed meat fibers in the fæces, indicating that the pancreas has failed to fulfill its task of assisting in the digestion of meat by the production of its ferment—the trypsin. Meat, when taken in large quantities, can thus cause the pancreas considerable overwork, which, in the long run, as is well-known, may cause trouble, as is shown by the fact learned from observation, that diabetes develops generally in meat eaters. Even in dogs an abundant meat diet can produce spontaneous diabetes, a fact we have already published. Diabetes may not only be due to the changes in the pancreas, but also as we have shown[278] to those in the thyroid gland, consequent upon such nourishment.
It is a very important fact that much meat can become most injurious to diabetic patients, and, as v. Noorden[279] observed, even slight cases of diabetes can be transformed into severe ones in consequence of such a diet; thus, in our opinion, in all severe cases of this disease meat should be prohibited.
Not only can diabetes, especially if of an hereditary nature, be increased by abundant meat food, but gout also, as is well known, may be caused thereby, and, existing, may be made worse. Such diet not only provokes the elimination of sugar, but of uric acid as well, which latter is a cause of gout.
Many authorities, especially Walker Hall and Haig, have demonstrated that even small quantities of meat can produce uric acid, especially when such meat contains a large quantity of nuclein bodies from which uric acid can be formed, such as the glandular organs, especially kidneys, liver, sweetbreads, shortbread, etc.
Meat food in abundance is also deleterious to other organs, as, for instance, to the intestines, which, receiving a food so easily digested and absorbed, lack the natural stimulus for good peristaltic movements, which can best be produced by a cellulose food like vegetables and fruit.
The greatest danger to the circulatory apparatus lies in meat, for, as already mentioned, the viscosity of the blood is thereby increased, as discovered by Determann,[280] and thus its circulation through the blood-vessels impaired. It is a well-established fact that arteriosclerosis can very often be observed in persons who have been largely addicted to a meat diet for a long time. Apoplexy also is more frequent among such.
These conditions can, however, be improved if the meat be suppressed and replaced by a vegetarian diet.
It would lead us beyond the limits of this book if we attempted to point out in an exhaustive manner various other dangerous consequences of a too abundant meat diet. All we desire is to discuss the question whether, in view of the various dangers to which a meat diet may lead, to which we have referred, we should or should not give up meat.
We think we should be guilty of fanatical prejudice if, because of the above accounts of the dangerous consequences ensuing on an unlimited abuse of meat, we should discard meat entirely, even in small quantities. Such a course is, indeed, strongly advocated by Haig,[281] but we cannot follow him so far.
It is quite true that even a moderate amount of meat may create uric acid, but there is not one hour out of the twenty-four that we do not produce a small amount of uric acid in our system, even if we exclude food of every description, such being the uric acid produced endogenously through the decomposition of the nuclein-containing albuminous bodies in the system, and which it is hardly possible to avoid; and if our kidneys be in good condition they will easily eliminate this small amount.
Should we therefore prohibit a person of 50 or 60, who has been in the habit of eating meat every day of his life since childhood, and who is in quite a normal state of health, from taking a moderate amount of meat once a day, and thus knock him out of all his old habits? We do not think this would be a wise proceeding on the part of any physician of wide clinical experience and of unprejudiced mind, as everyone must have observed that such a radical change in the habits of a lifetime may lead to consequences unfavorable to the general health. No! We desire to be temperate ourselves and to preach moderation. We must bear in mind that it is the immoderate use of meat that is to be condemned, and not its use in small quantities. We may, therefore, allow a moderate amount of meat, once a day, well cooked to destroy, if possible, certain harmful matters which can be rendered innocuous by sufficient cooking; and, by preference, we recommend boiled meat, as such food has all the nourishing properties of roast meat but less extractive substances, which might, perhaps, irritate the kidneys. Fresh meat should be taken in preference to canned food, as in the latter at times there is present certain additional matter, such as preservative salts, boracic acid, etc.
White meat is always preferable to red, although it is the pretension of Offer and Rosenquist that in their action both kinds of meat are similar; still, for clinical reasons, we agree with Professor Senator[282] who, from his experience, considers white meat better for the kidneys. The correctness of this opinion has been proved recently by the researches of Max Adler.[283] We have seen the sugar disappear from the urine of our diabetic patients when they were placed upon a diet poor in extractive substances, such as fish (except salmon and carp), veal, etc., and vegetables poor in carbohydrates; indeed, after such a diet they were able to tolerate quantities of carbohydrates without eliminating sugar. It is also of importance to remember that meats containing many extractive substances, or broths made from such meats, are capable of greatly increasing the blood-pressure; for this reason red meats should be forbidden to the aged. The meat of animals that have been hunted and subjected to great exhaustion before death should not be used, or used only with very great moderation. Meat strongly seasoned and spiced, or pickled, should also not be eaten. Sausages should also be omitted from the diet. We must also remember that fish is also a meat food, although on account of the greater amount of water it contains and its more tender structure, and especially because of its smaller content of extractive substances (except salmon, carp, etc.), it is preferable to meat proper; yet if taken in large quantities, especially such fish as salmon, it is quite as harmful as meat. At any rate fish, except the red-fleshed kind, should always be preferred to ordinary meat.
It is best not to give meat to little children nor to persons in advanced years—above 70, or earlier than this if they are decrepit. As found by Baumann,[284] Charrin,[285] Lafayette Mendel,[286] and others, the thyroid of infants contains no iodine; after the first year there is some, but even then very little. Baumann and Jollin[287] also found that the thyroid of old people contained only little iodine, which, as this is the main element of the thyroid gland, gives to such persons less chance of destroying toxic products; and by reason of this no meat should be given either to little children or to persons of advanced age.
We must also remember, as already mentioned, that proteid food is needed to build up the body, and this is not necessary in senility. All authorities agree that aged people require very little proteid in their food, and Prof. Magnus-Levy[288] accepts this opinion. There is, consequently, no necessity to force them to take meat, neither is it rational to permit its use, for they are more defenseless against the harmful products formed by the decomposition of meat than are younger people, for their thyroids and parathyroids, liver and kidneys, are degenerated. Thus they would be able neither to destroy such products nor to eliminate them from the body. Exception may be made in the case of the aged who are in robust health and enjoying a green old age, for in such we may expect to find more active ductless glands, and they will therefore be better able to resist the dangers of meat food.
There are certain precautionary measures that, perhaps, can mitigate such dangers; thus, by the daily use of water in proportion to the amount of meat the end-products of the meat can be washed away. We should also with much meat eat also much fruit and vegetables. Abundant meat diet produces acids in the system; but, as mentioned in Chapter X, by means of green vegetables we can raise the alkalinity of the blood. Whether much or little meat be taken, sour milk, kefir, yogurth, or even ordinary milk and cheese should be taken also. We have not mentioned here another danger from meat diet, which is the putrefaction that may arise in the intestines, but on which we have enlarged in Chapter XIX. By means of sour or ordinary milk, or cheese, the putrefaction can be avoided, through the lactic acid formed.
With a meat diet, especially when taken in large quantities, it is obvious that a good cleansing of the bowels will be all the more necessary, and this is best obtained by the addition to such a diet of fruit, vegetables, and sour milk.
By precautions such as these the harm from a too abundant meat diet may be reduced or at least limited; but for those who are desirous of attaining an advanced old age, the greatest moderation in the matter of meat consumption is strongly recommended.
When we study the nature of the diet enjoyed by persons who have lived to and over 100, we find, indeed, exceedingly few who are great meat eaters; very many are persons who eat no meat at all; and in many cases, also, the original meat diet was subsequently abandoned in advanced age. According to the report of the Collective Investigation Committee of the British Medical Association, the 55 centenarians whose cases they examined were, for the most part, small meat eaters.[289]