It is no doubt true that the normal individual is able to eat anything that anyone else may eat. Few, however, are normal and we frequently meet with those who cannot eat certain foods without suffering. Not infrequently a perfectly good food appears to be harmful to some individual and this seems to lend credibility to the old notion that what is one man's boon is another man's bane. Learned treatises have been written about these supposed idiosyncracies; yet, in most if not all such cases the trouble is not due to the food at all.
Some people develop skin eruptions after eating strawberries and some other foods. These people should be placed on a diet of strawberries and fed strawberries exclusively until the trouble ends. Some people are so sensitive to eggs that the consumption of only a small amount of egg will cause nausea, vomiting, purging, headache, urticaria, and other distressing symptoms.
Some people are constipated by cheese. This indicates enervation; correct the cause of enervation.
Oranges cause gas with some. Pears and apples do the same for others. Cooked cabbage and cauliflower produce gas in some. Many will have catarrh and a coated tongue so long as they use milk, even if it is but one glass a day. Some fruits cause diarrhea in some patients. Eggs and meat often bring on asthmatic attacks in certain individuals. This is, however, only after such individuals are already poisoned with an excess of protein. Many patients are made uncomfortable (have a heavy feeling in the stomach) when they eat spinach.
Much of the trouble that a certain food is supposed to give is the result of wrong combinations. Sometimes the trouble grows out of eating the food in excessive quantities, or it is blamed for the trouble caused by a too large meal. In some cases trouble is due to suggestion--the fixed idea that a certain food will cause distress. In many cases the trouble grows out of digestive derangements and ceases as soon as digestion has been restored to normal.
All these things have to be considered in planning a diet for a patient. When normal digestion is re-established these things disappear, but while digestion is still impaired, those foods that cause trouble are best omitted from the patient's diet. Often, however, a patient thinks that a certain article of diet causes him trouble, when it is only the wrong combination that produces the trouble. A patient will complain that acid fruits cause gas. Upon inquiry you find that these have been taken with a breakfast of cereal and sugar, and egg on toast. You put the patient upon an acid fruit diet and no trouble results. Wrong combinations are often the cause of trouble.