If you’re prone to gout, it’s best to ditch sugary sodas in favor of diet versions, new data show.

In a recent multi-center study of 15,000 adults, researchers tried to uncover possible links between sugary soda, diet soda, and increased levels of uric acid in the blood. Uric acid is a chemical made from substances called purines, which are found in some foods and in alcoholic beverages. Excessive amounts of uric acid can trigger gout—a disabling form of arthritis that causes inflammation and pain in joints, especially in the hands and feet.

The scientists found that the incidence of gout has doubled in the United States in the past few decades—and also that there has been a huge increase in the consumption of sugary soft drinks. In fact, they say, sugar-sweetened soft drinks now represent “the largest single food source of calories in the U.S. diet.”

After combing through scientific data based on study participants’ dietary habits, the researchers determined that fructose—the type of sugar usually used to sweeten soft drinks—appears to “significantly increase serum uric acid levels and the risk of gout.”

The researchers also looked at blood levels of uric acid in people who drank orange juice and other sweet fruit juices. Here, they found that juice lovers experienced just a modest increase in uric acid and a slightly higher risk of gout.

Why the difference in uric acid levels, since soda and juice are both sweet?

The researchers say added sugar is to blame. “Sweetened soft drinks contain large amounts of fructose from added sugars,” they note, “whereas orange juice and other sweet fruit juices contain naturally occurring fructose.”

Bottom line: If you have gout and also drink soda, diet soda’s better than regular. And—unless your doctor objects—feel free to have that glass of o.j.