Just as the physician who prescribes a diet for a diabetic should know the carbohydrate percentage of the different foods that he allows, so any one who undertakes to treat gout rationally should know the pur in percentage of the food administered. In the latter case it is true matters are very much simpler than in the case of the carbohydrate content of the diet.

1. Purin-free Foods

The products of female mammals and birds, that is, milk and eggs, must be considered purin-free. Traces of purin bodies, it is true, are found even in these articles of food, but from a practical standpoint they are negligible. It is immaterial whether the milk is administered in the natural state or fermented (sour milk, Yaourt) ; the derivatives of milk: cheese, butter, cream, milk sugar, casein, and casein preparations are, of course, also free from purin bodies. In the case of cheese certain reservations must be made, in so far as cheese, on account of the large quantities of bacteria that it harbors, may incorporate considerable quantities of purin bodies. Fish eggs (caviar) are also permitted in gout. An analysis made by S. Frankel (Vienna) showed: water 55.2%, nitrogen 5.1%, no trace of purin bodies.

All vegetables, with a few exceptions, contain so little purin that they can be used freely by gouty subjects. Most foods of vegetable origin are altogether purin-free, as, for instance, all varieties of sugar, vegetable oils, flour, leaves, roots, and stalks. In seeds, on the other hand, purin bodies have been found, but they are limited altogether to the plant embryos contained in seeds, and the latter occupy only a small part of the kernel. Nevertheless, it might be advisable in particularly severe cases of gout to forbid the use of seeds altogether (peas, lentils, hulled beans, maize, wheat, etc.), whereas, there is no objection to the use of flour made from these different seeds, for in process of preparation the purin containing plant embryo is completely removed from the flour.

Coffee beans, tea leaves, cocoa beans must be particularly mentioned because they contain abundant purin. Caffein is transformed into heteroxanthin, theobromin into methylxanthin, theophyllin into para-xanthin. In view of these transformations these bodies have very little to do with the formation of uric acid for the above purin bases are in no way related to gout in man. Moderate quantities of coffee, tea, and cocoa are, therefore, permitted without reservation; the use of larger quantities is, however, to be condemned on the basis of practical experience.