Higher mushroom consumption is associated with a lower risk of cancer
I don't put any credence on this. As the authors say this study merely suggests a possible relationship that needs to be investigated in a proper RCT.<p>What I don't like<p>1. Passive observational studies only. Therefore a huge risk of confounders (e.g. people who generally live a healthy lifestyle).<p>2. The effect size is not very large, making it much harder to winnow out confounders.<p>3. Invariably attempts to 'control' for confounders use simple linear models that that come nowhere close to actually controlling for confounders.<p>4. They generally only control for known confounders. If there is an unknown confounder it will get through and mess up the results.<p>5. It is really hard to tell what is a confounder and what is a legitimate node in the causal chain. As a simplistic example consider 'controlling' for lung cancer in a study of whether smoking is bad for you. Of course this would take away much of the reason why smoking is bad for you. You need a proper causal model informed by data - something that is hard to do. See Judea Pearl "Causality".<p>6. Note the heterogeneity of results. This suggests that things are going on that are not captured by the studies. Note also that the types of mushrooms don't seem to matter - a strange thing if there were some magic factor in mushrooms, given how mushrooms vary greatly in nutrient content.<p>7. Misuse of the term "significant" usually a shorthand for statistically significant. A very different thing from "practically significant, large enough to matter".