Until recently, diet in hay fever was a matter of avoiding meat and strawberries and the result was usually unsatisfactory. With the conception of hay fever as an anaphylaxis and the recent studies in food anaphylaxis, the subject of diet in hay fever assumes a new and inviting aspect.

This new view of diet in hay fever begins with Schloss's masterly study of a case of food anaphylaxis reported in the American Journal on Diseases of Children, 1912, No. 6. A good review of the subject with references to the literature will be found in the special Hay Fever and Anaphylaxis number of the Boston Medical and Surgical Journal, August 10, 1916, especially the article by Talbot.

Some physicians have long insisted that they could relieve hay fever by diet. For instance, I once asked a physician of large general practice what he did for hay fever. He smiled in an incredulous way that I have noticed before among people who never had hay fever and replied, "I find that if people will stop eating strawberries and not eat too much meat, they soon get rid of their hay fever." This answer surprised me for I knew that in his long practice, he must have seen many cases of hay fever and my experience had been that diet had no influence on the symptoms.

Then, there is Professor Dunn, already quoted in Chapter IX, who believes in the uric acid theory and says that, in his opinion, "hay fever is the result of improper eating and living." He has been able to prevent the annual attacks by using cold baths and excluding meat, tea, coffee and alcohol from the diet.

Any patient who can get rid of the annoying symptoms of hay fever by such simple means of diet and bathing should be urged to try it, whether he believes or disbelieves in the "uric acid poisoning" on which the treatment is based. My own experience leads me to believe that most hay fever patients require something more than dietary regulation to control the disease. For instance, in my own case, the disease appeared at an age when I had never taken tea, coffee or alcohol, during the summer vacation when I was living a hygienic out-door life, playing ball, cycling and swimming every day in the salt water. I remember one summer in camp by a lake among the pines, in which I lived Dr. Dunn's hygienic life for many weeks, drinking no tea, coffee or alcohol, eating chiefly fresh fish and green vegetables and swimming daily. My experience can be paralleled by many hay fever patients that as long as I remained among the pines, I was in perfect health but on going down into the valley, one breath of fragrant wind blowing over the fields would cause instant itching and swelling of eyes and nose and all the previous hygienic life up at the lake was no protection against the disorder. I have seen the hereditary form develop in three children of one family while they were at the seashore, bathing daily in salt water and living a care-free, active, out-door life, never taking tea, coffee or alcohol and not much meat.

So, I concluded long ago that there must be two kinds of hay fever, one kind curable by diet, bathing and exercise and another kind in which habits of living and eating made no difference; and I had seen mostly the other kind.

Now, there may well be cases of hay fever as there are known to be cases of that other anaphylaxis, asthma, that are pure examples of food anaphylaxis. In such a case, detecting the irritating food and removing it from the diet is the proper path to cure. The error in our former practice was to divide foods into good and bad for certain diseases. We should rather think of foods as good or bad for a particular patient.

The plain people long ago crystallized their experience in diet in the maxim that what is one man's meat is another man's poison, but your scientist will never believe anything until he sees it in a test-tube and physicians have kept on a few centuries behind the rest of the world prescribing diet for all cases of the same disease irrespective of whether or not it agreed with the patient. Witness the rigid diets for tuberculosis and Bright's disease. So, inevitably, there had to be a diet for hay fever and equally inevitably, the same diet did not agree with everybody.

Scientific men are fond of stating in scientific terms what everybody else knows already. While we have known for a long time that some foods did not agree with everybody, science is just now demonstrating that one man's meat is literally another man's poison by testing the different food proteins on the skin and calling the condition food anaphylaxis or food allergie.

As the patient reader of the chapter on Pollens will remember, the anaphylaxis or sensitiveness of the patient to particular pollens is tested by rubbing a speck of different pollens into scratches on the skin. This skin reaction as a test of anaphylaxis was used by Schloss with different foods before it was adopted in hay fever; and it has been taken up by the dermatologist also. The dermatologist has long suspected that certain skin diseases, as urticaria, and eczema, are aggravated or produced by certain foods but he has been unable to demonstrate just what foods were at fault. The problem was confused by the fact that he had found no guiding principle. Food that one patient could eat with impunity brought out a beautiful eczema or urticaria on another patient. The uric acid theory was one effort to solve this problem but it was not comprehensive enough and it was not true. Forbidding nitrogenous foods has been a favorite formula with some and they straightway advised milk, which is highly nitrogenous. The recent recognition that food sensitiveness is an anaphylaxis and the detection of the foods at fault by the skin reaction may supply the missing guiding principle that was needed to adjust a diet to the individual needs.

The poisonous element in food is the protein. The food itself will serve for the skin test but it is better to use the pure food protein, which gives clearer reactions and avoids contamination. Proteins of all our common foods are now obtainable in the drug trade put up in tiny capsules ready for the test.

The skin is cleansed with soap and water and dried. A number of little spots are denuded of their superficial epithelia by twirling a small brad-awl, which should not scrape deeply enough to draw blood. Most workers speak of scratching the skin but the brad-awl scrapes to the proper depth more quickly and easily. The spots are marked with the names of the foods to be tested, as milk, beef, potato, oats, etc., and a drop of a five per cent solution in water of the respective proteins is rubbed into the spots. One spot is left as a control, into which normal saline or 3% solution of milk sugar is rubbed, as the proteins of commerce are made up with milk sugar. Within five or ten minutes, there appears a redness and swelling, as with the pollens. As with the pollens, a patient who at any time has been poisoned or, as we now say, sensitized by any of these foods, still has circulating in his blood or fixed in his skin the reactive bodies to that food. These reaction bodies react to that food on the skin by redness and swelling. Food proteins that cause no redness and swelling are thought harmless for that patient. Foods that cause the reaction are thought to be those to which the patient has been sensitized and to which he has not developed or maintained an efficient defence. There is a contradiction here; for the reaction merely shows the presence of defense bodies in the blood and does not tell us whether that defence is or is not efficient. However, even if the argument limps, the results reported are encouraging. Some striking cures have been reported by simply excluding these foods from the diet. The test is simple and harmless if the scratch is not too deep and if the protein is not injected beneath the skin. If injected beneath the skin or rubbed into a deep scratch, the food proteins, like the pollen proteins, may be dangerous. If they are absorbed rapidly into the circulation of a patient who happens to have been sensitized to any of them, there is serious danger of anaphylactic shock.

If these observations prove reliable, here is a method of selecting a diet for the individual patient that surpasses in accuracy anything that we have ever known. If hay fever is ever a food anaphylaxis, this method of testing the food sensitiveness of the individual patient promises much; but these observations are still too new and unconfirmed and the skin reaction too uncertain to rely on it implicitly yet. There was a time, back in 1908 to 1910, when the skin reaction for tuberculosis too was highly valued. Enthusiasts proposed to test all the school children and all the soldiers and all the factory workers and segregate the tubercular by the skin test. The diagnosis of tuberculosis was to be put in words of one syllable.

That dream is over. Tuberculin skin reactions have now been made by the million and we know that a positive reaction means nothing but that, at some time, the patient has been infected with tuberculosis. The skin test does not tell us whether he has recovered long ago and built up a good defense or whether he is still sick with tuberculosis and will die of it. It reacts equally well in the healthy, vigorous subject who at one time has had a mild tuberculosis and recovered, in the patient with early phthisis and in the advanced case. In Kraus and Levaditi's Handbuch der Technik und Methodik der ImmunitÄtslehre, 1911, page 205, von Pirquet himself, the grandfather of all the skin tests, says, "A positive skin reaction indicates with certainty that the organism has been infected with tuberculosis. Of the localization, extent and prognosis of tubercular infection, a positive skin reaction gives no conclusion." Yet hundreds of physicians to-day are making diagnoses of tuberculosis by the skin test; for if there is one thing more difficult than to get a new idea into a doctor's head, it is getting it out again when the idea proves fallacious. So, I view these skin reactions for food and pollens with some suspicion of their real value in diagnosis and prognosis and as guides to treatment. Still, Talbot says, "Experience has shown that when a positive skin test is obtained for a food and that food is then excluded from the diet, the general condition of the patient almost invariably improves and in many instances a cure results." May his words prove true.