Evidence increasingly suggests that intelligence is associated with health and survival,1 2 3 although the reasons for this are not fully understood. To varying degrees, intelligence could mediate the long term impact of early adverse circumstances (such as overcrowding), influence the acquisition of factors that protect health, and reflect underlying biological mechanisms that regulate health. A cohort study in this week's BMJ by Gale and colleagues4 assesses whether intelligence can influence the acquisition of protective factors. In a large representative population study of more than 8000 British men and women, intelligence in childhood was associated with a vegetarian diet in mid-adulthood, and this was independent of educational attainment and social class.4

So what do the results say about the relation between …