A purin-free diet is one selected from milk, cheese, butter, white bread, cereal foods, nuts, and fruit. Milk suits gouty people very well, and milk has a special effect in reducing the number of intestinal bacteria, their number being less with a milk diet than with any other.
It is true that a purin-free diet has proved of benefit in certain cases of disease, but there is every reason to believe that in such cases an equal benefit would be obtained by a mixed diet, in which the protein consumption is kept down to a minimum. So long as temperance in the ingestion of protein is observed, it matters but little from what source the protein is derived.
From Walker Hall's experiments it would appear reasonable to administer sweetbread to gouty patients, since its nuclein portion is only slightly absorbed, for thymus sweetbread contains principally adenin, which is rapidly excreted, and pancreas sweetbread contains mainly guanin, an amino-purin incapable of increasing the urinary purin output and of exerting any injurious effects upon the tissues.
A fair proportion of vegetable food should be taken with two meals each day. The choice of vegetables will depend upon the digestive capacity of the patient; but excepting the potato, as a rule those vegetables that grow above ground are preferable to root-vegetables. Whereas the mineral constituents of meat exercise a marked effect in diminishing the solubility of a gouty deposit, the mineral constituents of most vegetables exercise a marked power in increasing its solubility. The vegetables, the mineral constituents of which I find are most efficacious in this respect, are spinach, Brussels sprouts, potatoes, cabbage, and French beans. At the same time, it must be borne in mind that with certain patients some of these vegetables may tend to produce some form of dyspepsia; and I cannot too strongly urge that in the dieting of the gouty no hard-and-fast rules can be laid down, but the idiosyncrasy of each patient to various articles of diet must be made the subject of careful observation and study. Due consideration should also be given to the patient's experience of what articles of diet disagree with him.
A diet that too largely consists of bread and starchy material leads to gravel in a number of cases. The frequency of uric acid gravel and stone among the rice-fed Hindoos is well known.
Starchy articles of food should be especially limited in amount in those gouty individuals who are subject to gastric hyperacidity (hyperchlorhydria). This condition is not due to gastric fermentation, but to an excessive secretion of hydrochloric acid by the gastric glands, and is a common cause of dyspepsia, and ultimately of gastric dilatation. It is due to an acid dyscrasia, as the result of which the secretion of gastric juice does not cease with the digestion of the protein materials of the food, but continues after they have been disposed of. The result is that a considerable portion of the starchy materials is kept back in the stomach, and this retained starch keeps up the gastric secretion, without at the same time giving it any work to do.
When intestinal fermentation and putrefaction occur, as evidenced by a sense of discomfort after a meal, I attach great importance to the reduction of the starchy articles of food, but not to the total exclusion of, what I believe to be comparatively harmless, the potato. It is remarkable how frequently one hears from gouty patients the emphatic statement, "I never eat potatoes." I must confess that I do not know of any good and sufficient reason for this wholesale condemnation of this common article of diet. Undoubtedly amongst those gouty patients who suffer from inability to digest starchy articles of diet - in other words, who suffer from amylaceous dyspepsia - a reduction for the time in the amount of starchy foods taken, including potatoes, is desirable; but the recognition of the existence of amylaceous dyspepsia is a fairly easy matter, and when present-it can be suitably treated. Certainly those who are gouty and fat should be very sparing in the use of potatoes, as of other carbo-hydrate forms of food. I wish, however, to protest against the too general exclusion from the food of the gouty of so common and useful an article of diet as the potato. The best form in which potatoes can be taken by the gouty is the crisp form, which requires thorough mastication and insalivation. Boiled new potatoes should be absolutely interdicted to the gouty.
Equally wrong, in my opinion, is the total exclusion of sugar from the dietary of all gouty individuals. Undoubtedly in certain individuals sugar may do harm, as in the cases of gouty persons who are fat, or who suffer from glycosuria, or who are prone to attacks of eczema; and in such it should be cut off; but that is no reason for the exclusion of it from the dietary of all gouty patients. I know of many gouty individuals who take sugar with absolute impunity. Some gouty subjects undoubtedly digest very badly all starchy articles of diet, and in such fats may well take the place of starches. Fat bacon, properly cooked, is generally well digested by gouty individuals.
Subjects who are both gouty and fat should avoid sugar, but undoubtedly sugar may be taken with advantage by those who are gouty and thin, and such subjects may also take in moderation marmalade and wholesome jams. Bread may advantageously be given as crisp toast, or in the form of rusks, or in the "Zwieback" or twice-baked form, as in these conditions it requires thorough mastication and insalivation.
In those cases in which it is desirable to reduce the carbo-hydrate intake such restriction may be achieved : - (1) By cutting off sugar, and all articles containing any form of sugar; (2) by carefully graduating (by weight) the daily intake of starch-containing foods, so as to attain the minimum consistent with adequate nutrition in each individual case; (3) by similarly graduating the intake of fats if necessary; and (4) by throwing the onus of nutrition to a considerably greater extent than previously upon fish, lean meat, green non-starchy vegetables, and gelatinous soups.