A study of 105 female college students found that those with the highest levels of stored iron had the highest grades. Fitness was also a factor, but while the effect of fitness was greater overall than the impact of iron status, both factors together had an even greater effect. The difference between fit women with normal iron levels and unfit women who were iron deficient was sufficiently large to to drop or increase a letter grade.
The association between the measure of fitness (peak oxygen intake) and grade was mediated by working memory.
Reference:
Scott, S. P., Souza, M. J. D., Koehler, K., & Murray-Kolb, L. E. (2017). Combined Iron Deficiency and Low Aerobic Fitness Doubly Burden Academic Performance among Women Attending University. The Journal of Nutrition, 147(1), 104–109. https://doi.org/10.3945/jn.116.240192
