For people with multiple sclerosis, drinking around 290 calories per day of soda or other sugar-sweetened beverages, or the equivalent of about two cans of nondiet soda, may be tied to more severe symptoms and a higher level of disability compared to people with MS who seldom consume sugar-sweetened beverages, according to a new study. Soda and other sweet beverages were the only type of food that was related to MS symptoms in the study.

The study by researchers at St. Josef Hospital in Bochum, Germany, involved 135 people with MS. Participants completed a questionnaire about their diet. Researchers then looked at how close each participants’ diet was to the Dietary Approaches to Stop Hypertension diet. The DASH diet recommends whole grains, fruits and vegetables, low-fat dairy products, lean meats, poultry and fish, and nuts and legumes. It limits foods that are high in saturated fat and sugar. 

Researchers also measured the participants’ level of disability using the Expanded Disability Status Scale, a common method to quantify disability ranging from 0 to 10 points. A total of 30 participants had severe disability. Overall, researchers did not find a link between what participants ate and their level of disability. 

For soda and sugar-sweetened beverages, the participants were divided into five groups based on how much they drank. The people in the top group drank an average of 290 calories of sugar-sweetened beverages per day, while the lowest group seldom drank sugar-sweetened beverages. People who seldom drank sugar-sweetened beverages consumed an average of seven calories in sugar-sweetened beverages per day, or the equivalent of one-and-a-half cans of nondiet soda per month.

The study found that participants who consumed the largest amounts of sugar-sweetened beverages were five times more likely to have severe disability than people who seldom drank sugar-sweetened beverages. Of the 34 people in the top group, 12 had severe disability, compared to four of the 34 people in the bottom group. The top group had on average a disability score of 4.1 points, while the bottom group had an average of 3.4 points.

Limitations of the study include the relatively small number of participants. The study also assessed participants’ diets and sugar-sweetened beverages at the same time as disability, so it is not possible to distinguish whether it is actually an aspect of diet, like sugar-sweetened beverages, that contributes to higher disability or whether more severe disease impacts a person’s ability to have a healthy diet. Additional studies are needed to evaluate whether sugar-sweetened beverages affect the course of the disease.

The study will be presented at the American Academy of Neurology’s 71st annual meeting in Philadelphia.