LONDON (Reuters) - A gluten-free vegan diet full of nuts, sunflower seeds, fruit and vegetables appears to offer protection against heart attacks and strokes for people with rheumatoid arthritis, Swedish researchers said on Tuesday.

The diet appeared to lower cholesterol and also affect the immune system, easing some symptoms associated with the painful joint condition, they said.

The study suggested diet could play an important role for people with rheumatoid arthritis who are often more prone to heart attacks, strokes and clogged arteries, said the team from Sweden's Karolinska Institute.

"These findings are compatible with previous results of vegetarian/vegan dietary regimens in non-rheumatoid arthritis subjects which have shown lower blood pressure, lower body mass index and lower incidence of cardiovascular disease," the researchers wrote in the journal Arthritis Research and Therapy.

About 20 million people worldwide have rheumatoid arthritis, an autoimmune disease caused when the body confuses healthy tissues for foreign substances and attacks itself.

In the study, Johan Frostegard and colleagues put 38 volunteers on gluten-free vegan foods and had 28 other people eat a balanced but non-vegan diet for one year.

The people on the diet excluding animal products and gluten -- found in wheat, rye and barley -- had lower levels of low-density lipoprotein, or LDL, the so-called "bad cholesterol" that can lead to clogged arteries. They also lost weight while the volunteers on the other diet showed no change.