People who were better nourished in infancy can score higher on IQ tests years later, regardless of the number of years they attended school. Between 1969 and 1977 Guatemalan children in four villages took part in a study on the effectiveness of nutritional supplements. Some were given atole - a protein supplement - while others were given a sugar drink called fresco. Between 2002 and 2004 1,448 participants were interviewed and given IQ tests. Individuals exposed to atole between 0-2 scored higher on tests of reading comprehension and cognitive functioning than the other children and this association remained significant after allowing for years of schooling.
You can find out more about this research at