Cyclosporin use, in addition to any other treatment, does not improve symptoms or reduce the individual's requirements for other forms of therapy (N Eng J Med, 1994; 330: 1846-51).

Today we are beginning to realize that treatment for IBD should reflect an individual programme rather than a general drug/surgery regime. There are many studies to support the use of nutritional therapy, whether dietary or intravenous, in the treatment of IBD.

In one of the most important and controversial studies, Dr AM Riordan and colleagues demonstrated that an elemental diet (see below) was as effective as steroid treatment for Crohn's disease, though most patients relapsed soon after resumption of their normal diet (Lancet, 1993; 342: 1131-4).

During the trial, 136 of the patients with Crohn's were all started on an elemental diet a protein free diet which includes a liquid nutrient preparation and other treatment was withdrawn. After 14 days, patients were randomized into two groups, either being treated with elemental diet and placebo, or steroids with dietary advice for healthy eating. Both groups were followed for up to two years by physicians who were unaware of group assignment. In addition, the diet group were asked to introduce a new food each day providing they did not react adversely to that food.

The results showed the common allergens cereals, dairy products and yeast were associated with Crohn's. The researchers concluded that the process of food allergy testing could provide an effective strategy for the long-term management of CD.

Some of the improvement on this restrictive diet may be because it is a diet low in histamine which is found in high amounts in yeast and dairy products.

Diamine oxidase is the agent which metabolizes histamine in the gut. Patients with Crohn's disease seem to have up to 50 per cent less diamine oxidase in their guts than healthy controls (Agents Actions, 1990; 30: 267-70). This element cannot be given as a supplement. Therefore, a histamine-free diet excluding fish, cheese, hard-cured sausage, pickled cabbage and alcohol is the best way to help those who are intolerant (Lancet, 1994; 343: 113).

In the commentary which followed this trial, several doctors rejected the idea of diet easing or curing the disease, claiming that it only made people feel better about having it (Lancet, 1994; 343: 112). Others believe dietary toxicity as well as environmental pollution should be urgently addressed since many of these pollutants contain chemicals which are known to deplete the immune response (BMJ, 1994; 309: 1090).

As the debate continues, it should be noted that earlier trials have come to the same conclusions as Dr Riordan about the importance of diet (Lancet, 1985; ii: 177-80; Arch Dis Child, 1987; 62: 123-27; Lancet, 1990; i: 816-19).

!APat Thomas