Although this year soda has received much criticism for its high sugar content and suspected adverse health effects, diet soda has been a target of flawed criticism as well. Last year, for instance, a flawed study tied the consumption of diet soda to diabetes. Unfortunately, the study authors neglected to control for the weight of the subjects. Once this factor was considered, the correlation disappeared. Now there is a new report to add to the pile of ridiculous assertions: A new National Institutes of Health study is suggesting diet soda consumption is linked to depression.
The study, which will be presented at the American Academy of Neurology s 65th Annual Meeting in San Diego in March, involved nearly 264,000 people between the ages of 50 and 71. Participants in the study answered questions about their consumption of a variety of different beverages soda, tea, fruit punch and coffee between the years 1995 and 1996. About 10 years later (from 2004 to 2006), the same people were asked if a doctor had diagnosed them with depression since the year 2000.
Among the findings: Those who drank more than four cans or cups per day of any kind of soda were 30 percent more likely to develop depression than the non-soda drinkers. Those who drank four cans of fruit punch a day were about 38 percent more likely to be depressed than those who didn't drink sweetened drinks. The risk appeared to be greater for people who drank diet rather than regular soda, diet rather than regular fruit punches and for diet rather than regular iced tea. Those who drank diet sodas had a 31 percent greater risk of depression than non-soda drinkers, while diet fruit punch drinkers had a 51 percent greater risk compared to non-fruit punch drinkers.
Furthermore, people who drank four cups of coffee per day were about 10 percent less likely to develop depression than those who drank no coffee.
The results of this study are hard to swallow says ACSH s Dr. Ruth Kava. They are all based on self-reports, and there is no sound biological basis for the conclusion that there is an association between beverage choice and depression. It would be just as likely that depression might affect a person s choice of beverage than the other way around.
Dr. Bloom has seen some bad studies in his day, but believes that this is top five material. He wonders what would be the effect on depression from drinking transmission fluid. He quips, It makes as much sense as anything in this article.