Features February 2005 Issue

Arthritis Nutrition Myths Dispelled

There’s little scientific evidence to support dubious diet claims.

Though the link between diet and arthritis is tenuous at best, there is no shortage of claims, anecdotes, and tantalizing tales about how what we eat can have a direct and healthy impact on how our joints feel. Myths about diet and arthritis are big business, helping to sell books, supplements, and hope to millions of people trying to manage a disease with no known cure.

We certainly don’t expect to slow this ongoing flood of often unsubstantiated and sometimes spurious claims, but we can help you make sense of some of the stories that range from the dubious to the downright unbelievable. Here’s our take on a few of the current beliefs about diet and arthritis.

The nightshade diet
Potatoes, eggplant, tomatoes, and green peppers all belong to the same family of plants known as nightshades. Some people believe that eating members of this plant group leads to a buildup of toxins (glycoalkaloids and other substances) that can make their arthritis worse by interfering with an enzyme in their muscles and causing pain.

“This is no scientific evidence to support this belief,” says Andrea Dunn, R.D., L.D., a dietitian at The Cleveland Clinic.  “And by cutting out these vegetables you miss out on a good source of vitamin C.”

The less-than-scientific support for the nightshade diet comes, in part, from a 1993 study in which people with arthritis were asked to avoid nightshade foods. These people said their symptoms improved. However, the study was judged not to be credible since it lacked a control group, which is required to account for the placebo effect and the natural waxing and waning of symptoms that is common with arthritis.

Calcium as pain-fighter
Though some would like to believe that taking more than the normal amount of calcium can help manage arthritis, this false hope may come from the confusion of osteoarthritis with osteoporosis.

Those with osteoporosis, or weakened bones, do benefit from getting extra calcium (through diets or supplements) because calcium is a key building block in the ongoing repair and rebuilding of bones. However, calcium is not a key component of joint cartilage, so consuming extra amounts of it has little impact. On the other hand, you still need to get your recommended daily dose—1,500 milligrams of calcium a day for women over age 45 and men over age 65.

Studies have also shown that women who get less than the minimal amount of vitamin D (less than 200 units or 5 micrograms a day) seem to be at greater risk for rheumatoid arthritis, and that osteoarthritis seems to progress faster in those with chronically low levels of vitamin D.

Vegetable-juice fasting
“Though adding more vegetables to your diet is a healthy move, there is no evidence to support the notion that routine fasting with vegetable juices can help your arthritis,” says Dunn. According to this belief, the strategy is to go a week or so, living on nothing but vegetable juices, especially carrot, celery, cabbage, and tomato juice. The belief is that by consuming such juices, which are low in fat and sugar, you can improve your body’s ability to absorb important minerals like calcium, magnesium, and phosphorus.

“A healthful diet requires fruits and whole grains, as well as vegetables,” says Dunn.

Green tea to the rescue
Using green tea to fight arthritis is a belief that may be a bit easier to swallow than other folk tales. Tea—whether green or black—contains an abundance of antioxidants known as flavonoids, which help inhibit the production of prostaglandins, which in turn play a role in causing inflammation and pain.

According to Dunn, a few early studies have suggested that drinking tea may reduce inflammation or slow cartilage breakdown. However, these preliminary findings need further study before any tentative conclusions can garner more solid scientific support. 

The mega-vitamin approach
While a general vitamin with minerals might make a valuable addition to your daily diet, there is no evidence that taking large doses of vitamins will help keep your arthritis in check.

It’s true that getting minimal daily requirements of various vitamins and minerals may play a role in reducing your risk of getting cancer, heart disease, osteoporosis, and other medical problems. But no controlled studies have yet shown that megadoses of vitamins can slow the course of osteoarthritis.

This unsupported belief may rest on the fact that vitamin C (as well as vitamin E and beta carotene) are antioxidants with the ability to disarm free radicals (electrically charged molecules) that may play a role in osteoarthritis, rheumatoid arthritis, and other forms of arthritis. But the unsettled question is whether extra doses of vitamins beyond the normal daily allotment are really needed to counteract the build-up of such damaging molecules.

Gout and cider vinegar
Claims that drinking cider vinegar can help clear up gout don’t seem to hold water. This belief rests on the mistaken idea that cider vinegar can somehow dissolve the build-up of uric acid crystals in your big toe and other joints, which are a hallmark of gout. Consuming such an acidic beverage may instead cause stomach and bowel irritation if used in large quantities.

However, gout is one of the few forms of arthritis in which diet seems to play a genuine role. A recent study in the New England Journal of Medicine, which followed the eating habits of a large group of health professionals, found that risk of gout increased with the consumption of meat and seafood, but decreased with the consumption of low-fat dairy products. As a result of this study, it has been suggested that milk proteins help the body rid itself of uric acid.

The glucosamine conundrum
Though glucosamine has been shown in preliminary studies to help in relieving arthritis pain, this supplement, made from seashells and coxcombs, is not a miracle pill that may someday halt or reverse the course of the disease. Even glucosamine’s more accepted role as a way to relieve arthritis pain without risk of stomach irritation is coming into question.

A recent study in the American Journal of Medicine examined 205 patients with osteoarthritis of the knee and found that, after 12 weeks, those who used a placebo had just as much pain relief as those who used glucosamine. A separate Canadian study found that glucosamine had no impact on the frequency of arthritic flare-ups when used over a six-month period.

Of course, this is far from the final word on this widely used supplement. Perhaps advice that is more conclusive will emerge from the large, long-term study of glucosamine and chondroitin that is underway at the National Institutes of Health. Until then, remain cautiously open-minded about the use of this supplement in the management of arthritis.