Does Diet Cause Arthritis?

These are the apparently logical questions underlying most dietary claims for arthritis, claims, to be fair, that are often made in good conscience. There's plenty of anecdotal evidence: Aunt Betsy stopped eating red meat and threw away her canes; the mail-carrier's sister-in-law started sipping Devil's Claw herbal tea, and she's never had a painful joint since; or an author claims that eating tomatoes and green peppers is bad for your arthritis because they're related to deadly nightshade...

Unfortunately, from the perspective of arthritis specialists, most theories about food causing, curing or even affecting arthritis are just that — theories that remain to be proven true, untrue or partially true. Reading strictly from the book, the medical community has repeatedly noted that there's no connection between diet and arthritis until scientific evidence proves otherwise — particularly when other safe and effective treatment options are available.

In recent years, though, changes have opened a chink in the previously unassailable armour of science. In the first place, doctors are no longer held in the same regard they once were. Their patients have begun to recognize what doctors themselves are slowly coming to accept: that they can't possibly know it all. There's simply too much science being done for any one person to assimilate, and medical specialties, with their constantly increasing databanks of knowledge, are pushing the limits of understanding available to any one physician further and further from his or her grasp.

Thus, some doctors at least, are opening their minds to the possibility that certain long-held beliefs have to be re-examined in the light of new knowledge, and with the recognition that some things — food and its potential role in arthritis, for instance — may not be so easily determined or dismissed as they once were. They're beginning to accept that there may well be exceptions to the established rules: There are simply too many people claiming that this or that has had an affect on how they feel to be ignored.

The key, though, is the word 'exceptions.' Becoming more open-minded doesn't mean a scientist can ignore what facts there are, and the central fact is, no study has ever shown that there's anything like a universal dietary influence on arthritis, even if some people's arthritis — the exceptions to the rule — may be affected in as yet unaccountable ways by foodstuffs they ingest. In fact, beyond any purported benefit from ginseng or carrots or charcoal-broiled beef, there are at least two well-known reasons why some people experience an improvement in their symptoms after engaging in a particular dietary experiment. The first is the cyclical nature of arthritis; the second is the placebo effect.

'For reasons still poorly understood,' says rheumatologist Dr. Andrew Chalmers 'many types of arthritis [including osteoarthritis, rheumatoid arthritis and lupus] go through periods of spontaneous remission and flare-up of symptoms, quite independently of treatment.' These periods can last several days or weeks or months and are entirely unpredictable. Consequently if someone were independently to begin a new treatment, such as dietary modification, at about the same time that a period of remission began, then it's easy to see how he or she would attribute the improvement to the new treatment. And even if that person's symptoms never returned, Chalmers says, 'it would still be impossible to say unequivocally that it was a result of a particular treatment. By contrast, in controlled scientific experiments, arthritis researchers do their utmost to take into account this variable, so that it won't distort the results.'

Scientists are also aware of the power of mind over body. Medicines are tested against a placebo (an inert substance) because studies have shown that the symptoms of up to 30 per cent of clinical test subjects improve, simply because they believe they're doing something positive for their condition. The literal translation of the Latin placebo is, 'I please,' and embedded in that simple phrase is the powerful phenomenon of positive thinking: I believe my treatment is good for me; therefore, I will get better. In the hard-nosed arena of bringing pharmaceutical compounds to market, a medication must, at the very least, significantly outperform the placebo effect to be considered effective.

'If you have arthritis, the downside of the placebo effect is that nothing is actually being done for your arthritis,' says Chalmers, 'and the absence of symptoms does not mean the disease is cured. Regrettably, for most people with arthritis, the placebo effect is short-lived, and the illness returns with increased severity.'

Still, there are ways in which food might be connected with arthritis. First, some people are allergic to certain foods, and it's conceivable that some individuals may have a type of allergic reaction in their joints. Second, certain types of diets—with particular amounts of calories, protein and fatty acids—may affect the inflammation that occurs with arthritis.

Dr. Richard S. Panush, an immunologist at Saint Barnabas Medical Center in Livingston, New Jersey, is one of the leading scientific experts in North America on food and arthritis. In the late '80s, Panush conducted rigorously controlled food-challenge studies to test the theory of food-induced arthritis. He selected 30 people with inflammatory arthritis whose claims that their symptoms were related to foods were sufficiently compelling to warrant further studies. The results were then published in 1990 in the highly respected Journal of Rheumatology.

Although he's the first to admit that his observations aren't conclusive and need confirmation in larger scale studies, Panush found that 'most patients alleging food-induced rheumatic symptoms did not show these on blinded challenge [a form of test in which subjects don't know what they're ingesting], but some did. Probably not more than five per cent of rheumatic disease patients have immunologic sensitivity to food(s). Such patients have only been identified by controlled challenge studies. These observations suggest a role for food allergy in at least some patients with rheumatic disease.'

If Panush's observations hold true when projected over a general population, then people who develop inflammatory arthritis resulting from an allergic reaction to specific foods are fairly rare, and if most people who believe their arthritis is caused by food are mistaken, then this insight has a far-reaching implication.

Panush seems to have confirmed a new and rare form of inflammatory arthritis related to food allergies. But what about the other 95 per cent of people who have other types of inflammatory arthritis—say, those with RA or psoriatic arthritis? The causes appear not to be food-related, no matter how much an individual believes the contrary.

This page was last reviewed/updated on : 02/23/2008