The title is misleading, at least on the IQ claim. The underlying study was observational and did not claim causation.
Medical journals and their associated media summaries are awash with low-certainty studies that get de-nuanced and overhyped. These studies are relatively easy to do - not to denigrate the work put in by the original study authors (it’s not their fault the press sensationalize their work). But for strong causative claims you ideally would have blinded controlled randomized trials. Sometimes such trials are not feasible, but that doesn’t mean you get to claim causation anyway just because the work to prove it is too hard.
Medical journals and their associated media summaries are awash with low-certainty studies that get de-nuanced and overhyped. These studies are relatively easy to do - not to denigrate the work put in by the original study authors (it’s not their fault the press sensationalize their work). But for strong causative claims you ideally would have blinded controlled randomized trials. Sometimes such trials are not feasible, but that doesn’t mean you get to claim causation anyway just because the work to prove it is too hard.