Observational Studies Often Overshadow Clinica...(ogen 29 citing articles (61.7 percent) w...),Health

The study appears in the Dec. 5 issue of the Journal of the American Medical Association.

"Counterarguments defending vitamin E or estrogen included diverse selection and information biases and genuine differences across studies in participants, interventions, co-interventions, and outcomes. Favorable citations to beta carotene, long after evidence contradicted its effectiveness, did not consider the contradicting evidence," the Greek researchers wrote.

They said "it can be difficult to discern whether perpetuated beliefs are based on careful consideration of all evidence and differential interpretation, inappropriate entrenchment of old information, lack of dissemination of newer data, or purposeful silencing of their existence. Regardless of the reasons, better communication between research specialists and evidence-based clinical science may improve this situation and may lead to more rational and concerted translational efforts in basic, pre-clinical, and clinical research."

In a statement released Tuesday, the Council for Responsible Nutrition, which represents the dietary supplement industry, had this comment on the JAMA finding: "...the reality is that science doesn't always move forward there is some back and forth and while research may contradict itself, that should not be interpreted to mean one type of study trumps another, particularly when different studies ask and answer different questions. Seemingly conflicting data can exist side by side, when one understands that not all studies are asking the same questions in the same populations."

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The Family Caregiver Alliance offers advice on evaluating medical research and clinical trials.