Study: Diet Soda, Diet Fruit Drinks Linked to Increased Depression Risk

Calorie-free drinks come at a cost for older adults, according to a new study that links diet soda and diet fruit drinks with an increased risk of depression.

Researchers in the federal study analyzed data on more than 263,900 U.S. adults aged 50 to 71 who answered questions about their beverage consumption between 1995 and 1996, according to Live Science. Then, from 2004 to 2006, the same people were asked if a doctor had diagnosed them with depression since 2000.

The study found that those who drank diet soda regularly were more likely than those who drank regular soda daily to be diagnosed with depression. People who drank diet soda regularly were 31 percent more likely to be diagnosed, while there was a 22 percent increased risk for those who drank regular soda, researchers said.

People who drank an exorbitant amount of any type of soda regularly, four or more cans, were 30 percent more likely to have received a diagnosis of depression than people who did not drink soda at all. They were 51 percent more likely to be diagnosed with depression.

The study also found that people who drank four or more cups of coffee a day were 10 percent less likely to be diagnosed with depression than non-coffee drinkers.

The study implies correlation, not causation, in terms of the link between diet soda or diet fruit drinks and depression. Researchers weighed factors such as age, sex, education, smoking status, physical activity, body mass index and energy intake for the subjects. However, they asserted that it's possible other circumstances, such as a family history of depression or stressful life events, could explain the association.

The findings are in line with a few other previous studies that found a link between frequent consumption of sweetened beverages and a higher prevalence of depression, the researchers said. A 2011 study backs up the finding that regular coffee consumption could result in a reduced risk of depression for women.

The study was supported by the National Institutes of Health, the National Institute of Environmental Health Sciences, and the National Cancer Institute.