Maternal diet and mental retardation in southern Georgia, USA

The diet of each of 250 mothers was correlated with the I.Q. (intelligence quotient) of her child. When the I.Q. was above 90, no systematic relationship was observed. Below an I.Q. of 70, all mothers consumed a similar diet--one with a smaller amount and variety of fruits and vegetables, but larger amounts of yams, greens, corn, rice and dry legumes. This diet was uniquely deficient in none of the common nutrients. It seems more possible, therefore, that the correlation with diet could be due to the presence of a toxicant, such as aflatoxin.