By Kathleen Doheny
WebMD Health News
Reviewed by Arefa Cassoobhoy, MD, MPH
Nov. 1, 2013 (San Diego)- Women who drink one or more sugar-sweetened sodas a day might raise their risk of getting rheumatoid arthritis, according to a new study that links RA risk to the sugary habit. The study does not prove cause and effect.
About 1.3 million Americans have RA, a chronic and potentially disabling disease that causes pain, stiffness, and swelling in the joints, and limits how well they work.
''We found an association only for sugar-sweetened beverages," says Yang Hu, a researcher at Harvard School of Public Health who conducted the study. Hu presented the findings this week at the American College of Rheumatology annual meeting.
The link does not mean that sodas cause RA, Hu says. He says drinking sodas could reflect other lifestyle habits known to boost RA risk, such as smoking.
The American Beverage Association, an industry group, disputes the findings.
Sodas & RA: Study Details
Hu and his colleagues looked at data from two large studies of nurses, which have evaluated diets and other data for decades.
Hu looked at the diet and other health information from about 173,000 women during two different time periods. Every 4 years, the women reported how many sugary beverages they drank. This included regular colas with sugar, caffeine-free colas with sugar, and non-cola sodas. Diet soda was not included.
During the time periods studied, 883 women were diagnosed with RA. Hu found those who drank one or more sugar-sweetened beverages a day, compared to those who drank either none or less than one a month, had a higher risk of getting a form of RA known as seropositive. It is often a more severe form of the disease.
The way the study was done has limitations. People often don't accurately remember what they ate or drank in the past.
Beverage Industry Group Responds
The American Beverage Association says it needs more detail to fully evaluate the study.
"The National Institute of Arthritis and Musculoskeletal and Skin Diseases notes that while the causes of rheumatoid arthritis are not known, genetic and hormonal factors are considered the most likely causes and women are more likely than men to develop this autoimmune inflammatory disease," its statement says.
The study is interesting and the link is potentially plausible, says Eric Ruderman, MD, professor of medicine at Northwestern University Feinberg School of Medicine. He reviewed the findings but was not involved in the study.
"We're always looking at what drives risk in RA,'' he says. The disease has both genetic and environmental components, experts know. Those factors weren't taken into account in the study. The next step, he says, is to ''drill down into the pathology and try to understand why.''
The National Institutes of Health funded the study.
These findings were presented at a medical conference. They should be considered preliminary, as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.
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