School breakfast improves verbal fluency in undernourished Jamaican children.

School feeding programs exist in many countries, but few have been properly evaluated. In this study, the short-term effects of breakfast on children's cognitive functions were examined. The subjects were 97 undernourished (weight-for-age < or = -1 SD of reference) and 100 adequately nourished (weight-for-age > -1 SD) children in four primary schools in rural Jamaica. The children were randomly assigned to a group provided with breakfast or a group given a quarter of an orange as a placebo, and then given a battery of four cognitive function tests. After a few weeks the treatments were reversed and the tests repeated. Undernourished children's performance improved significantly on a test of verbal fluency when they received breakfast, whereas that of the adequately nourished children did not change (breakfast x group interaction, P < 0.05). There were no other effects of breakfast on test scores. The findings extend those of a previous Jamaican study conducted under more controlled conditions, and support the targeting of school meals to undernourished children.