Most bedwetters grow out of the problem after age three. But some don't. And when physical causes such as a urinary tract defect or a chronic infection have been ruled out, the situation becomes emotionally trying for parents and child alike. In fact, 99 per cent of these children continue to wet the bed indefinitely, in spite of strategies such as denying them fluids in the evening or strapping moisture-sensitive buzzers to the mattress.
In the 1920s and 1930s, a few doctors discovered that some bedwetters lost urinary control after they ate particular foods, but had perfect control when they avoided them. Unfortunately for millions of bedwetting children since then, those observations went largely unnoticed for decades. Then in 1957, a scientific study once again showed that avoiding certain foods meant no more bedwetting for many youngsters.
A closer look at those children showed they had 'oedematous' (fluid-filled) bladder tissues, much like the swollen nasal tissues in a person with hay fever. A swollen bladder is a smaller bladder; it can't stretch to hold the amount of urine it should. And if the sphincter muscle controlling flow out of the bladder is also swollen, the problem is compounded: the muscle tires more easily and cannot close tightly enough to hold back urine, especially when the person is asleep and relaxed. The result is overnight 'accidents'. When food allergens are avoided, the swelling subsides and the bladder can hold urine during sleep.
'Control of food allergy is effective in curbing bedwetting in four out of five patients,' says Dr James Ñ Breneman, chairman of the Food Allergy Committee of The American College of
Allergists. He bases that assertion on a study of 400 bedwetters whose loss of urinary control could not be explained by physical problems other than allergy. Cow's milk was the most common offender, followed by wheat, egg, corn, chocolate and pork (Basics of Food Allergy, Charles C. Thomas).
Dr Breneman suggests keeping a detailed diary of diet and night-time accidents to help identify foods at fault in bedwetting.