Why are so many epidemiology associations inflated or wrong? Does poorly conducted animal research suggest implausible hypotheses?

There is growing concern among epidemiologists that most discovered associations are either inflated or false. The reasons for this concern have focused on methodological issues in the conduct and publication of epidemiologic research. This commentary suggests that another reason for discrepant findings may be that animal research is producing implausible hypotheses. Many animal studies are methodologically weak, and the animal literature is not systematically reviewed and synthesized. Moreover, most bodies of animal literature may be so heterogeneous that they can be used selectively to support the plausibility of almost any epidemiology study result. Epidemiologists themselves also do not consistently conduct systematic reviews of bodies of biological evidence which might point to sources of bias in an evidence base. Animal research will likely continue to provide the biological basis for epidemiological investigation, but substantial improvement is needed in how it is conducted and synthesized to improve the predictability of animal studies for the human condition.