Preliminary Reports Linking Diet Drinks and Depression are Unsubstantiated

Findings Promoted Despite Not Yet Being Presented or Published

ATLANTA (January 9, 2013) — The abstract, “Sweetened beverages, coffee and tea in relation to depression among older US adults,” is speculative, misleading and at this time, unsubstantiated. The study upon which the abstract is based has not yet been published or peer-reviewed. Having said that the Council cites the following as major limitations of this research based on available information:

  • The findings are preliminary and have not been verified. Given that the findings are only in abstract form and have yet to be published in a peer-reviewed journal, it is difficult to assess the veracity of the study, and we question why these findings have been made public. This is especially noteworthy given a recent incident where study findings that were prematurely promoted by Brigham and Women’s Hospital (BWH), were later found to be so weak that BWH issued a public apology. According to a news report regarding the BWH study, Dr. Steven Nissen, chair of the Cleveland Clinic’s cardiovascular medicine department was quoted as saying, “Promoting a study that its own authors agree is not definite, not conclusive and not useful for the public is not in the best interests of public health.”
  • It is unlikely that beverages would have much, if any, impact on depression. According to the National Institutes of Health (NIH), “Depression is a common but serious illness” and “is caused by a combination of genetic, biological, environmental, and psychological factors.” There is no scientific evidence that one component of the diet, such as diet drinks or low-calorie sweeteners, is responsible for depression.
  • The results do not make sense. According to the researchers, coffee may decrease the risk of depression while diet beverages increase the risk. However, many people sweeten their coffee with low-calorie sweeteners. Why would low-calorie sweeteners in diet beverages be expected to increase the risk of depression while low-calorie sweeteners in coffee decreased the risk?
  • Other factors likely caused the depression. The study was observational, so cause and effect cannot be determined. Because so many factors, such as genetics, biology and the environment, influence the development of depression, it would be extremely difficult to link a single food to this outcome. It is more likely that one or more of those factors likely caused the depression and the individuals just happened to also drink diet beverages.
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