OTHER FORMS OF FOOD ALLERGY: FOOD AND KIDNEY DISEASE
The question of whether foods might produce excess immune complexes in the blood and thus cause the same sort of damage to the kidneys is a highly controversial one. Two groups of doctors, one working in Japan, the other in Miami, Florida, have made a special study of children with kidney disorders, and they believe that food is the source of the problem for some of these children. When put on an elemental diet (a synthetic food mixture that contains a minimum of antigens, children with certain types of kidney disease may improve. Those who do recover are then challenged with various foods and some reproduce their original symptoms – protein loss in the urine, and retention of water leading to puffiness in various parts of the body.
The food most often implicated is cow’s milk – the most common allergen of childhood. But the majority of these children appear to be sensitive to several foods, and to various airborne allergens, such as pollen. By putting these children on restricted diets, their symptoms have been fully or partially controlled. There are reports that neutralization treatments are also useful, where the food or foods concerned are difficult to avoid.
It must be emphasized that children such as these are rare, and the vast majority of cases of kidney disease are due to other causes. Nevertheless it does seem that food allergy can cause kidney damage in some children. Whether it can affect adults in this way is an open question.
Almost all the children affected in this way are atopic – that is, they show one of the classical allergic disorders, such as asthma or eczema. This raises the possibility that IgE and mast cells are somehow involved in the damaging reactions in their kidneys. While this is possible, it does not seem that IgE has a central role. Neither is it entirely certain that deposition of immune complexes is to blame. Some of the available evidence suggests that it is, but other studies point to different forms of immune reaction producing the damage.
Finally, Type-I allergic reactions to airborne allergens, such as pollen, may sometimes be linked with kidney disorders. Reactions of this type are thought to be extremely rare. It is not known whether IgE and mast cells are responsible for the damage in the kidney, or whether some other mechanism is at work.
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