Background Micronutrients are potentially important determinants of adult outcomes such as educational attainment. Copper and zinc have known effects on several medical conditions and cognitive development. Elevated copper and depressed zinc is a common trace metal imbalance.

Methods We estimate the correlation between the copper/zinc ratio (Cu/Zn) in childhood (year 1980) and educational attainment in adulthood (year 2010). We use the Young Finns Study (YFS) combined with the Finnish Linked Employer-Employee Data (FLEED). The regression models account for confounders such as other biomarkers and parental observables.

Results We report a sizeable, negative correlation between Cu/Zn and educational attainment as measured by education in years, grades as well as the likelihood of completing university education. For example, a one standard deviation increase in Cu/Zn decreases the probability of university education by ∼4%.

Conclusions The findings are consistent with a Cu/Zn effect influencing cognitive functioning early in life. Future research should explore more deeply the precise mechanisms by which Cu/Zn affects educational attainment.