It is probably not in the nature of things that one should expect such brilliant therapeutical results by the use of a purin-free diet as are obtained by Dr. Haig. For it is evident he is obsessed by the doctrine that uric acid is the causative factor in many, nay, most diseases, and proclaims this gospel with such emphasis that he cannot fail to arouse the enthusiasm of the chronic invalid, especially when, as is usual, other methods of treatment have failed to produce any material benefit. One, however, is not long in determining that many forms of disease - often refractory in the ordinary course - are unquestionably greatly ameliorated by adopting a diet containing a minimum of purins; but careful reflection and calm dispassionate consideration of the cases leave one in much dubiety as to whether the benefit must be ascribed to the restriction of the purins and not to some other factor.

The only way to elicit the curative or preventive properties of any diet is to test it in suitable cases. On account of an irresistible power of attraction, my therapy was for many years strongly tinctured with the purin-free theory, and I made a point of treating every chronic case which failed to respond to recognised therapeutical method by the imposition of a purin-free diet, and during this quest I was able to form very definite views as to its limitations. I have tested the system in the following groups of cases: -

Group I. Headaches

This group comprises headaches of a periodical nature, sometimes accompanied by sickness, at other times not, but always of the character so generally ascribed to the condition known as uric-acidaemia. All these cases occurred in ladies who refused to adopt a rigorous purin-free diet, but as a compromise agreed to give up tea, coffee, and cocoa. In the six cases I had noted the results were remarkable, as after a preliminary exacerbation of the headache it disappeared never to return.

I am of opinion that the great majority of such headaches in women are due to caffein poisoning, and for a long time are kept at bay by an extra dose of the poison, so that it becomes quite a common thing for the sufferer to fly to another cup of tea in order to obtain relief, with disastrous results in the long run. Tea, coffee, and cocoa are nerve poisons, cardiac poisons, and cerebral excitants, and the headache is sufficiently explained by the toxic factor, without having recourse to the statement that xanthins are analogous to purins, and hence converted into uric acid, or one of its congeners, and as such accumulate in the body. Whenever the dose of the poison is reduced to the amount the body can tolerate, the bad effects cease. Probably the temporary relief obtained by a cup of tea is due to the fact that caffein quickly acts as a diuretic, and leads to an increased excretion of the nitrogenous elements, especially of urea, and the fatigue products generally. This is possible only with moderate doses, because it has been experimentally demonstrated that the greater the quantity of caffein absorbed, the less in proportion is it metabolised, and, as much of it is retained, the total urinary purin is proportionately diminished. This cumulative action sufficiently explains the toxic effects of large quantities of tea and coffee. However close may be the association between xanthin, hypoxanthin and uric acid, there is no evidence to support the belief that methyl-xanthins, the urinary degradation products of caffein, theobromin, and theophyl-lin, can be converted into uric acid, or exercise similar functions. As a matter of fact, the methylated purins found in tea, coffee, and cocoa are, when ingested, not oxidised to uric acid, but appear in the urine as purin bases.

In this connection my own personal experience is of interest. For quite half a dozen years I had, on an average, three attacks of migraine each week, which never failed to be relieved by small doses of citrate of caffein, antipyrin, salicylate of soda, and bromide of potassium. In my extremity I have tried all these remedies singly, in pairs, and even three together, without avail. It was absolutely essential to combine the whole four to effect a cure, and even although diuresis was effected by other remedies, the severity of the headache was never mitigated. In common with Dr. Haig I ascribed the attacks to uric acid, but quite ten years ago a pair of cylindrical glasses effectively banished my torture by correcting an infinitesimal degree of astigmatism.