sentences:  However, foods containing high amounts of mercury, such as shark, swordfish, king mackerel and tilefish, might cause mental retardation.One study from a developing country, Guatemala, found that poor growth during infancy, rather than low birth weight, was negatively related to adolescent performance on cognitive and achievement tests.A later related very long term study looked at the effect of giving 6–24-month-old children in Guatemala a high protein-energy drink as a dietary supplement.