Nov. 14, 2012 -- Men with osteoarthritis of the knee may want to avoid sugar-packed soft drinks. That's the advice of researchers who found that drinking sugary soda is associated with progression of the disease in men.
No such link was found in women in the study of more than 2,000 people with knee osteoarthritis.
"Our main finding is that in general, the more sugary soda men drink, the greater the risk that knee osteoarthritis will get worse," says researcher Bing Lu, MD, DrPh. Lu is assistant professor of medicine at Harvard Medical School and associate biostatistician at Brigham and Women's Hospital in Boston.
If you're thinking that is because the calories in soda may contribute to being overweight or obese -- a known risk factor for knee osteoarthritis -- think again.
Much to the researchers' surprise, the link between knee osteoarthritis and sugary soft drinks could not solely be explained by weight, Lu says.
"We very carefully [took into account] weight in the statistical analysis. We controlled not only for the general categories of overweight and obesity, but also for patients' specific body-mass indices, or BMIs," he says.
When the men were divided into obese and non-obese, the link between sugary drinks and worse knee damage held true only in the non-obese men.
This suggests that soft drinks worsen knee osteoarthritis independently of the wear and tear on the joints caused by carrying around excess weight, Lu says.
In people with osteoarthritis, the cartilage in a joint wears away in some areas. The function of cartilage is to reduce friction in the joints and serve as a "shock absorber." The wearing away of cartilage leads to pain and other symptoms.
Nearly one in 100 people have evidence of knee osteoarthritis on X-ray. And nearly 19% of women and 14% of men over age 45 have joint pain, stiffness, and other symptoms of knee osteoarthritis, according to a 2007 study.
In addition to obesity, known risk factors include:
Prior injury to the knee
Extreme stress to the joints
The study was presented this week at the American College of Rheumatology Annual Meeting in Washington, D.C.