The theory is that migraine occurs when the blood vessels in the brain constrict and then suddenly widen. What causes this pattern is still not known. Conventional medicine uses prescription and over-the-counter drugs to alleviate pain. But these do nothing to help cure the illness. Even worse, some can cause rebound headache (that is, headaches brought on by the medication itself).

In contrast, by addressing and treating the root cause of migraine, sufferers may have a much better chance of long-term relief. Consider the following options.

* Investigate food allergy. Many common food items can act as triggers to migraine, including chocolate, wheat, corn, milk, nuts, shellfish, sugar and oranges.

Some speculate that foods containing amines - which affect the diameter of blood vessels - are a cause. Amines can be found in any fermented, pickled or marinated food as well as in avocados, bananas, caffeinated drinks, chicken liver, monosodium glutamate (MSG), chocolate, citrus fruits, nuts, processed meats, raisins, red wine, ripened cheese, onions and lentils. Removing allergens can dramatically reduce the occurrence of migraine (Lancet, 1983; ii: 865-9; Ann Allergy, 1985; 55: 28-32).

* Is it an infection? Infection with Helicobacter pylori (the organism that causes peptic ulcers) may predispose people to migraine. In one trial, 40 per cent of migraine sufferers were found to have H. pylori infection. Intensity, duration and frequency of attacks of migraine were significantly reduced in all participants in whom the bacteria were eradicated (Hepatogastroen-terology, 1998; 45: 765-70).

* Boost magnesium. Compared with healthy people, migraine sufferers have lower blood and brain levels of magnesium. Taking around 600 mg per day was found to significantly reduce migraine frequency (Cephalalgia, 1996; 16: 257-63). But lower doses of magnesium can also be effective. Just 200 mg per day has been shown to reduce the frequency of migraines in 80 per cent of those treated (Headache, 1990; 30: 168).

* Eliminate excitotoxins. Foods containing aspartame may trigger migraine attacks (Headache, 1988; 28: 10-3; N Engl J Med, 1988; 318: 1200-1). MSG binds to it and transports copper - another possible migraine trigger.

* Stress relief. Reducing and effectively coping with stress may help reduce the frequency of attacks. Yoga, regular massage, meditation or any relaxing hobby should be part of your prevention regime.

* Reduce salt intake. Some sufferers find this helpful (Headache, 1981; 21: 222-6).

* Vitamin B2 (riboflavin). There is reasonable evidence for the benefits of vitamin B2 for migraine sufferers. Supplementing with 400 mg of vitamin B2 reduced the number of migraine attacks by half, although once an attack had occurred, the vitamin had no effect on either the severity or duration (Cephalalgia, 1994; 14: 328-9). Other studies concur (Neurology, 1998; 50: 466-70; Cephalalgia, 1997; 17: 244). Vitamin B2 is generally safe, although some people taking high doses may develop diarrhoea.

* Fish oil. This contains the anti-inflammatory fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which modify the action of prostaglandins, hormone-like substances involved in pain and inflammation. Taking 1 g per 10 lb of body weight has been reported to reduce the frequency and symptoms of migraine (Am J Clin Nutr, 1985; 41: 874; Am J Clin Nutr, 1986; 43: 710).