DHA is an omega-3 fatty acid found in fish oil. It is important for brain development in children. A recent study, published in Clinical Pediatrics (2008 May;47(4):355-62) looked at 175 healthy four-year-olds who were supplemented with 400 mg per day of DHA or a placebo. Prior to supplementation and after four months of supplementation, the children were given four tests of cognitive function.
The group given the DHA had blood levels of DHA increase by 300%. Higher DHA levels were associated with improved performance in listening comprehension and vocabulary as measured by the Peabody Picture Vocabulary Test. For each increase of 1% in serum DHA, there was as much as a nine-point improvement in the test score.