Consumption of foods high in vitamin C appears to protect against inflammatory polyarthritis, a form of rheumatoid arthritis involving two or more joints, new research suggests.

The findings, which appear in the Annals of the Rheumatic Diseases, stem from a study of more than 20,000 subjects who kept diet diaries and were arthritis-free when the study began.

The analysis focused on 73 subjects who developed inflammatory polyarthritis during follow-up between 1993 and 2001, and 146 similar subjects who remained arthritis-free.

Dr. Dorothy J. Pattison, from the University of Manchester in the UK, and colleagues found that low intake of fruits, vegetables, and vitamin C raised the risk of inflammatory polyarthritis. For example, subjects who consumed the lowest amounts of vitamin C were three times more likely to develop the condition than their peers who consumed the highest amounts.

Although lower intake of fruits and vegetables seemed to increase the arthritis risk, the trends were not statistically significant, the researchers point out. Similarly, low intake of vitamin E and beta-carotene was only weakly linked with an increased risk of inflammatory polyarthritis.

The findings contrast with a recent report linking high doses of vitamin C with worsening disease in guinea pigs with osteoarthritis, the more common type of arthritis that occurs with aging.

In an interview with Reuters Health, Pattison said that these opposite findings may reflect the fact that rheumatoid arthritis and osteoarthritis are caused by different physiologic problems. With rheumatoid arthritis, an autoimmune disease, the body attacks itself, she explained. In contrast, osteoarthritis involves a degenerative process that worsens over time.

Pattison added that her group has a study being reviewed for publication that looks at the effect of meat consumption on the risk of arthritis.

SOURCE: Annals of the Rheumatic Diseases, July 2004.