O-71 - Serum beta-carotene shows a strong protective mortality association in cohorts (RR 0.69) that randomized trials exclude
A referenced fact resting on no data of the Viewpoint’s own. Discriminating value: even when dietary measurement error is bypassed with a biochemical assay, the cohort association failed to replicate in randomized trials — evidence that the confounding/selection problem, not just measurement error, drives nutritional-cohort associations.
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Why this is evidence
A strong protective cohort association measured with an objective biochemical assay (so dietary self-report error is bypassed) that randomized trials nonetheless exclude. H-31 reads this as proof that confounding/selection, not merely measurement error, generates nutritional-cohort associations, so they cannot carry causal weight; H-41 confines it to single-nutrient supplement trials (unrepresentative of whole-diet cohort inference) and points to trial triangulation as the corrective.