Tuberculosis is essentially a wasting disease, conspicuous features of the condition being loss of appetite, disturbed digestion, interference with assimilation, and a resultant loss of flesh - both muscle and adipose tissue. One essential in treatment, therefore, is to improve the resistant and recuperative powers of the body by getting the patient to eat properly, and to eat a sufficient amount.
There is no hard and last rule for the dieting in tuberculosis. The disease may show itself at all ages, and in many varied forms; the stage and severity of the disease, and the presence or absence of special complications, have to be considered. Thus the diet of a young subject affected with acute tuberculosis, where there is extensive and active mischief with fever, and general constitutional disturbance, differs from that of a patient whose weight is almost average for his height, and in whom there is a limited and quiescent lesion. Similarly, haemoptysis, tuberculosis of larynx with difficulty in swallowing, dyspepsia due to general tuberculous infection, tuberculous enteritis with associated gastric disturbance, tuberculosis of the kidney and urinary tract, the glandular enlargements due to tubercle, and the various surgical affections of bones and joints, all require a regimen of their own. It will be most convenient first to discuss the Principles of Feeding, and the dietetic treatment of tuberculosis generally, and after that to take up the special indications in tuberculosis of the various organs.
In considering the principles of feeding it is necessary to refer to the importance of thorough oxygenation of the blood, a therapeutic factor which bears directly on the processes of general nutrition. As the proper method of oxygenating the blood is by the continual supply of fresh air and sunlight, the patient should, so far as possible, live in the fresh air day and night, irrespective of the weather. This promotes a good appetite, increases the digestive powers, and so enables the full effects of a judicious dietary to be obtained. A further important point is, that breathing should be carried out properly. It is of comparatively little value to put a child or young person who is a mouth-breather on to a proper dietary, if the oxygenating power of the blood and tissues is greatly below the normal, from a cause which can be readily removed. Breathing exercises, carried out in a systematic and thorough manner, are frequently of the greatest value in these cases.
As has been stated above, tuberculosis is a wasting disease, therefore the main point in the dietetic treatment is to increase the amount of food, so that the patient's weight shall increase and remain stationary at a little in excess of the patient's highest known weight before becoming infected with tuberculosis. There is great variety of opinions among sanatorium physicians as to the quantity of food necessary to do this, some believing in a process of forced feeding, in which a large excess of food is taken; this system is not to be commended. It is probably safe to assume that those physicians who use the lowest dietary standards consistent with satisfactory gain in weight are adopting the soundest lines of treatment.
While the food as a whole has to be increased, special importance attaches to the increase of the proteins and fats.
Bardswell and Chapman found that by increasing the amount of protein up to 150 grammes daily, i.e., by an increase of from 25 to 30 per cent. on the amount of protein found in a normal diet (Voit standard, see p. 20), the best results from a clinical and metabolic standpoint were obtained.
Increasing the intake of protein beyond this point, viz., 150 grammes daily, is not associated with any better clinical results, and the extra protein ingested is immediately excreted, throwing a considerable strain upon the excretory organs. With regard to fat and carbohydrates, in the large majority of tuberculous cases, the importance of energy-giving food is recognised, especially when the patient is much below the proper body-weight.
Fat is the best energy supplier, being less bulky, and it is as a rule more readily taken in these cases. For a tuberculous patient not engaged in active muscular exercise, an increase of 30 per cent, of the fat and carbohydrate foodstuffs usually suffices; if the patient is taking muscular exercise, a larger amount of these foodstuffs could be consumed.
As a rough estimate of the extent to which the nutritive material should exceed the normal diet of a non-tuberculous subject, it may be said that the diet in a case of tuberculosis should contain about one-third more. Of this third, the greater part should be given in the form of animal protein, and more especially meat, eggs, milk. Animal proteins are selected because there is good reason for believing that they have a very special value in the treatment of tuberculosis. The explanation of this special value is, I believe, to be found in part in the special influence of a diet rich in proteins on the thyroid gland, as shown by the results of experimental observations (p. 557). The fats and carbohydrates are mainly increased by the addition of milk, butter, cream, yolk of eggs. There is no special virtue in increasing the breadstuffs and farinaceous foods.