To find out what proportion of patients reported a relationship between eating certain foods and their seizures, researchers from Philadelphia, USA, carried out a questionnaire survey of adults with epilepsy attending a clinic at Thomas Jefferson University.

Out of 193 participants, only 11 reported noticing a link between foods they ate and their seizures. Four people identified sweeteners and carbohydrates as a trigger, three meats and poultry, and one dairy products. What level of education each participant had achieved made no difference to their answers, nor did whether their seizures were controlled. The report was published in the journal Epilepsy & Behavior in October.

The lead researcher, Dr Ali Asadi-Pooya, had previously investigated the same question in the city of Shiraz, in Iran. In a study there,
over half of families with a child with epilepsy said that they had noticed a link between eating certain foods and having seizures. The types of food most often thought to cause seizures were dairy products, sour foods, fruit and vegetables. In a parallel study of nurses and doctors in the same city, 58% of participants also believed this link existed, and 28% said they had personal experience of a seizure triggered in this way. The same foods, plus meats, fish and food additives, were reported as triggers.

This difference is so large that it can really only be explained by cultural differences in perception of risks. The types of epilepsy seen in the US are not biologically fundamentally different from those seen in the Iran, nor is treatment for epilepsy very different.

There is a long tradition in Iranian medicine, dating from the 10th century and the work of Ibn Sina (also called Avicenna), a highly influential philosopher, doctor and scholar, that epileptic seizures can be triggered by eating certain foods. Though his work was widely accepted and admired in European universities until the 1700s, there is no general perception that foods trigger seizures in the West today.

Epilepsy Research UK regularly receives queries from members of the public about whether certain foods cause seizures. Perhaps typically of modern Western food worries, the foods most often suspected are all features of highly processed diets: colourings and preservatives, monosodium glutamate, refined sugars and sweeteners. However, there is no evidence that any type of food consistently triggers seizures in people with epilepsy (though there are some extremely rare types of 'reflex' epilepsy where seizures can be triggered by eating very specific foods).

It's very important that doctors reassure patients that no types of food should be avoided by people with epilepsy. Otherwise important nutritional groups might be cut out of the diet, causing problems especially for children.