The study was presented on Wednesday, 6 March 2013, at the Infarma pharmaceutical congress, which took place in Barcelona. It is the first study to show that the administration of DAO reduces migraines.

Migraines, which cause severe pain on one side of the head as well as increased sensitivity to light and sound, affect 12% of the population. 90% of cases are due to a deficiency of the DAO enzyme in patients. This enzyme is responsible for metabolizing histamine, a molecule present in many foods, especially dairy products and citrus fruits, which is subsequently eliminated in the urine.

People with a DAO deficiency cannot eliminate histamine, so it passes into the bloodstream and accumulates in the plasma, causing adverse effects such as migraines and gastrointestinal disorders. Therefore, treatment would involve taking a DAO supplement before meals. "It isn't addictive and doesn't cause side effects because, unlike analgesics, it's a dietary supplement rather than a medication", assured Joan Izquierdo.

Migraine patients with a DAO deficiency should also watch their diet and eliminate foods high in histamine. In this regard, the study recommends avoiding processed foods such as cold meats, dairy products, citrus fruits and alcoholic beverages, as they contain high levels of histamine and are also DAO inhibitors. "We have always suspected that there is a correlation between eating certain foods and migraines", said Izquierdo. Until now, this had not been scientifically proven and the correlation was called into question by the Spanish Association of Neurology.

The study took a year and a half and involved analysing a hundred patients with severe chronic migraines who experienced between nine and fourteen episodes of pain a month. 81% were women and 19% were men, a similar proportion to migraine patients. The average age of the patients who participated in the study was 41 and participants were chosen according to diagnostic criteria set by the International Headache Society. The study was also double-blind, which means that neither the patients nor the doctors knew which group was being given the enzyme and which was being given the placebo.

The professor also stressed that migraines are not hereditary. What is transmitted genetically is the DAO deficiency, which in most cases, though not all, triggers migraines. Therefore, 90% of migraine cases are caused by the deficiency of this enzyme, while the cause of the other 10% is still unknown.