Feb. 19, 2003 -- The so-called "Mediterranean diet," already believed to help prevent heart disease and some forms of cancer, may also reduce the pain and swelling of joints stricken with rheumatoid arthritis -- although relief may not begin for at least six weeks, suggests a new study.
Still, significant improvement was reported by most of the 26 arthritic patients who followed the well-studied dietary regimen for three months. The Mediterranean diet includes olive and canola oils as the primary dietary sources of fat -- along with plenty of fish, poultry, produce, and legumes, say Swedish researchers. By comparison, no relief was reported by another group of 25 patients who followed a typical Western diet.
Their finding, published in the March issue of Annals of Rheumatic Diseases, is the latest to suggest arthritis relief may result from this eating plan, which is typical on Crete and other Greek islands. Just over two years ago, University of Buffalo researchers found that mice fed high doses of fish oil and vitamin E -- abundant in the two oils studied by the Swedish investigators -- had reduced levels of a specific protein that causes joint swelling and pain. And just a few months earlier, Greek investigators found that a similar Mediterranean diet reduced the onset of rheumatoid arthritis by nearly three-fold compared with those who ate less olive oil and fewer fruits and vegetables.
And once again, it appears as though the ingredients in these key cooking oils may be the key to relief. In addition to being good sources of heart-healthy fats, olive and canola oils are rich in oleic acid and vitamin E. Like vitamin E, oleic acid has an anti-inflammatory effect and is thought to reduce inflammatory protein levels.
The fish eaten by these study participants didn't have the same high levels of omega-3 and omega-6 fatty acids found in cold-water fish such as salmon, mackerel, and others associated with a reduced risk of heart disease and other conditions. But the nutrients in these oils may have a similar anti-inflammatory effect. And like produce, they're also good sources of other antioxidant phytochemicals believed to reduce inflammation and inhibit tissue damage. The other foods in the studied diet -- legumes, poultry, and cereals -- are low in fat, which may further reduce inflammation.
Rheumatoid arthritis occurs when the immune system mistakenly attacks the joints -- and other parts of the body in more severe cases -- leading to inflammation and pain that eventually erodes bone and soft tissue. It affects more than 2 million Americans, most of them women.
In this study, which lasted only three months, researchers studied people with rheumatoid arthritis, average age 58, who had the disease for at least two years. Those on the Mediterranean diet first began to experience relief after six weeks (although their cholesterol levels dropped after three) and improvement continued throughout the study. In addition to being provided with meals, those patients also received nutritional counseling on how to cook more healthfully. They lost an average of seven pounds by study's end.
Meanwhile, those on a diet richer in dairy foods and red meat -- typical in Sweden as well as the U.S. -- also received prepared meals, but no counseling. They lost no weight and reported no measurable symptom relief. None of the study participants in either group had previously followed the Mediterranean or a vegetarian-based diet.
"The results of this intervention program indicate that a Cretan Mediterranean diet suppresses disease activity in patients who have stable and modestly active rheumatoid arthritis," write the researchers. "Thus, by eating a Mediterranean diet for three months, patients with RA can obtain better physical function and increase their activity. In theory, even a minor effect that is persistent and accumulates over time might be important."