Want to Avoid Knee Arthritis? Eat More Fiber

Eating foods high in fiber may reduce the risk of knee arthritis, new research shows. Ohio State University

New research shows that people who eat more fiber are much less likely to develop arthritis of the knee.

In a paper published in the journal Annals of the Rheumatic Diseases, scientists analyzed data from more than 6,000 Americans participating in two long-running studies. In one group, those who ate more fiber (the top 25 percent of participants in terms of fiber consumption) had a 61 percent lower chance of developing the condition, compared to those who ate the least. In the other group, the upper quartile had a 30 percent lower chance of experiencing osteoarthritis, compared to those in the bottom 25 percent.

To single out the effect of fiber, researchers controlled for age, diet and many other factors, and "still saw a benefit of fiber," says Virginia Kraus, a researcher and physician at Duke University School of Medicine who wasn't involved in the study. Those who eat the most fiber tend to weigh less and to be better educated.

Dietary fiber has been shown to help prevent obesity and inflammation, two conditions which make the development and symptoms of arthritis worse. Obesity in particular is strongly linked with arthritis, in part because being heavier puts more strain on the knee, and wears down the cartilage therein. Researchers show that eating more fiber changes the composition of bacteria in the gut and "decreases the leakiness of the bowel so bacterial-produced toxins have less of a chance of penetrating into the systemic circulation where, if not cleared by the liver—and less is cleared when liver is fatty—[the toxins] can induce inflammation and pain," Kraus says.

The findings are particularly relevant as the average American doesn't consume enough fiber, eating only 15 grams per day. The Dietary Guidelines for Americans 2015-2020 recommend that women older than 51 eat 22 grams per day and men 28 grams per day, says study first author Joy Dai, a postdoctoral fellow at Boston University School of Medicine.

Reducing your risk of developing knee arthritis is especially important given that it is not a simple problem to treat once it develops. Recent research has found, for example, that steroid injections for knee arthritis aren't effective, and are no better than a placebo treatment. That work was published May 16 in JAMA.

Asked if those at risk of knee arthritis should eat more fiber, Kraus answers in the affirmative. "It is heart healthy and potentially joint healthy," she says.