Professor Charles Mackay, working at Sydney's Garvan Institute of Medical Research, identified how fibre in the diet plays a major role in ensuring a person's immune cells function properly, the Australian Associated Press reports.
"This does provide a direct link for the way immune cells work with the sort of things we eat."
This broken-down fibre was found to "profoundly affect immune cell function", Prof. Mackay said, and without it the immune cells appeared more likely to go awry.
Autoimmune disease refers to disorders in which a person's immune system mistakenly attacks part of the body, causing inflammation. "When (immune cells) go bad they cause inflammatory diseases, so asthma, rheumatoid arthritis, inflammatory bowel disease." Prof. Mackay said.
A lack of dietary fibre could also be behind the rise in type 1 diabetes, he said.
The research suggests that having a healthy diet rich in fruits, vegetables, grains, nuts and seeds would reduce a person's risk of autoimmune disease.
It also helped to explain why food supplements that affect the balance of gut bacteria were known to reduce the symptoms of some inflammatory conditions.
Prof. Mackay said dietary fibre, or roughage, was otherwise known to reduce the risk of cardiovascular disease and certain cancers plus it ensures you will be regular.