In the past month he's been to the doctor twice and on both occasions they've given him Cleanprep to clear him out because he's been so bloated. The doctor has now scheduled a colonoscopy and a biopsy of the bowel. Is this really necessary.

Professor Harry Seftel replies:

By far the commonest cause of constipation is a deficiency of fibre in the diet and not eating enough fruit and vegetables. But presumably you've done all that. Remember that it's not enough to eat the odd cucumber or tomato per day. He's the sort of person that should have between five and ten servings of fresh fruit and vegetables per day in their natural and fibrous form. Many people neglect to take the diet seriously.

In addition, I also advise you to add bran to his diet three times a day. You should make every effort to increase his fibre intake. This is not an easy matter, and you've got to take it seriously. Only when that has all failed should you ask yourself whether there is some underlying problem.

The paediatrician has obviously decided that his constipation is not due to his diet, but a problem in the bowel. A colonoscopy is quite a thing for a child, but if it has to be done, it has to be done. What I'm saying is that you should only resort to this if it is really necessary, and you have made every effort to ensure that his diet is adequate in fibre.