Vegan diet may ease arthritis, study finds

· Reduced swelling hints at unexpected immunity link
· Research raises hope for rheumatoid patients

Rheumatoid arthritis patients may be able to improve their symptoms by switching to a vegan and gluten-free diet, a study in Sweden has found.

The researchers' findings were based on a small study group of only 30 patients with the disease and they are not yet sure why the diet change appeared to work. However the research team, which demonstrated changes to the immune system that may underlie the beneficial effect, believe it has identified an area that would repay further study. "I think it is a quite unexpected and interesting finding," said Prof Johan Frostegård at the Karolinska Institutet rheumatology unit in Stockholm, who led the study. "The effects on the immune system are quite new."

Rheumatoid arthritis - a different condition from osteoarthritis - affects around 350,000 people in the UK. It is more common in women than men and can afflict people of any age. It is caused by the immune system attacking the lining of the patient's joints, causing them to become inflamed and painful. Over time the damage can restrict movement. At present there is no cure, although the disease can be slowed down if diagnosed early.

Over a year Frostegård and his team followed 30 patients who kept up the new diet for at least three months and 28 on a normal diet, monitoring the progress of the disease and levels of various chemicals in the blood. By the end of the study the vegans had a modest improvement in the number of swollen joints (down from an average of 5.3 to 4.3). There was also a large drop in the level of a chemical in the blood called CRP, which doctors use to measure inflammatory activity in the body. There was no significant improvement in the group who ate a normal diet.

At the same time, the vegans developed a lower body mass index, had lower levels of bad cholesterol and higher levels of immune system factors that potentially inhibit the inflammatory reaction. The research was reported in the journal Arthritis Research and Therapy.

Frostegård conceded the study was too small to draw definitive conclusions and that it would need to be repeated. Convincing patients to switch diets for such a long time was very difficult, he said. "There is no big money from the drug companies for these kind of studies."

Another problem with studying diet is that, unlike with a pill, the clinical trial cannot be truly "blinded", meaning that the patients know if they are in the intervention group or the control group.

Lynn Love, the director of operations at the National Rheumatoid Arthritis Society, a charity that supports people with the disease, welcomed the study. She said that there were many anecdotal reports of changing diet having an effect on symptoms, but the only food regime with any research evidence to back it up was a Mediterranean diet including olive oil.