October 10, 2013
By Robert H. Shmerling M.D.
Beth Israel Deaconess Medical Center
Many people assume that diet has a lot to do with the development of certain diseases, including arthritis — after all, “you are what you eat.” When it comes to arthritis, this notion is largely myth.
While healthy diets may increase the chances of good health, current understanding of the most common forms of arthritis suggests almost no role of diet in prevention or treatment. While it's true that diet may affect certain joint disorders, the role of diet is strongest only in rare situations.
Gout, for example, may be worsened by diets high in purines, a form of protein found in sardines, liver and other organ meats, but this effect is rather weak for most patients. Alcohol intake, if a major part of one’s diet, plays a stronger role. One recent study linked the risk of developing gout with alcohol (especially beer), and another linked it with meat and seafood intake. However, the large majority of people who drink beer or eat meat or seafood never develop gout. And for most gout sufferers, taking medicine to treat or prevent gout is more effective than a particular diet.
Patients with celiac disease, a rare condition in which there is an autoimmune reaction to gluten in the diet, occasionally have arthritis as part of the illness. Though it may not always be easy, a gluten-free diet can reverse this condition as long as the restrictive diet is followed.
For the more common forms of arthritis and joint pain (including degenerative arthritis, rheumatoid arthritis, lupus, tendonitis and bursitis) there is no clear connection to diet. Efforts to remove certain types of food or add others in an effort to treat arthritis have met with inconclusive or disappointing results. Recent research has identified an association between low vitamin D intake and degenerative arthritis, but we don't know if it's helpful to take extra vitamin D to prevent or treat degenerative joint disease. In the absence of a particular vitamin deficiency, no clear benefit from supplemental vitamins or nutrients has been established. Weight loss may help to prevent or treat gout or degenerative arthritis, but it's not reliably effective.
While diet may not cause most arthritis, the joints and the intestinal tract are closely linked in certain diseases. Inflammation of the joints (arthritis) and the intestinal tract (colitis, proctitis, ileitis) occur together in “inflammatory bowel disease,” (IBD) a group of illnesses that includes Crohn's disease and ulcerative colitis. The cause of IBD is unknown. While the bowel problems are the major feature for most patients, up to 20% develop a type of arthritis that can be a serious cause of suffering and reduced function. When arthritis is present in IBD, it most commonly affects the spine (spondylitis) and/or one to three joints in the extremities, especially the ankles and knees. Diet isn't thought to play any significant role in either the joint or bowel inflammation, although bowel inflammation may lead to poor absorption of nutrients. Treatment of colitis is often effective in treating the arthritis in this condition; otherwise treatment is similar to what is offered for other forms of spondylitis.
Why does the myth about diet and arthritis persist? As is true in other fallacies about health and disease, much of it probably relates to wishful thinking about control. It's much more appealing to think we can treat a condition by controlling our diet accordingly, rather than accepting an unknown, uncontrollable cause of illness and treating it with medications. It also seems intuitive that diet ought to matter a lot in the development of disease. Perhaps it does and we just don't have a good grasp of which diets matter in which diseases.
It may be true that you are what you eat, but having arthritis or worrying that you may someday develop it are not reasons to restrict your diet in most cases. Beyond the usual recommendations of maintaining a balanced diet and trying to achieve optimal body weight, the current impact of diet on arthritis is probably small or negligible.
Of course, that could change as we learn more over time about the link between nutrition and disease. But given our current understanding, this myth isn't likely to become truth anytime soon.
Robert H. Shmerling, M.D. is associate physician at Beth Israel Deaconess Medical Center and associate professor at Harvard Medical School. He has been a practicing rheumatologist for over 20 years at Beth Israel Deaconess Medical Center. He is an active teacher in the Internal Medicine Residency Program, serving as the Robinson Firm Chief. He is also a teacher in the Rheumatology Fellowship Program.