Fish Oil Makes You Smarter

A recent review of studies, including about 50 that have not yet been published, supports the theory that docosahexaenoic acid (DHA), a form of omega-3 fatty acid found in fish oil, improves cognitive and behavioral performance.

Based on the studies, researchers suggest that small differences in brain concentrations of DHA, such as those that most likely occur between infants fed supplemented or unsupplemented formulas, may result in subtle effects that currently are difficult to detect but could be significant. Animal studies have provided convincing and consistent evidence linking a decrease in brain concentrations of DHA to decreased performance on cognitive or behavioral tests.

American Journal of Clinical Nutrition, Vol. 82, No. 2, 281-295, August 2005
© 2005 American Society for Clinical Nutrition

Review Article
Is docosahexaenoic acid, an n–3 long-chain polyunsaturated fatty acid, required for development of normal brain function? An overview of evidence from cognitive and behavioral tests in humans and animals1,2,3

Joyce C McCann and Bruce N Ames

1 From the Nutrition, Metabolism and Genomics Center, Children’s Hospital Oakland Research Institute, Oakland, CA (JCM and BNA)

This review is part of a series intended for nonspecialists that will summarize evidence relevant to the question of whether causal relations exist between micronutrient deficiencies and brain function. Here, we focus on experiments that used cognitive or behavioral tests as outcome measures in experimental designs that were known to or were likely to result in altered brain concentrations of the n–3 fatty acid docosahexaenoic acid (DHA) during the perinatal period of "brain growth spurt." Experimental designs reviewed include observational breastfeeding studies and randomized controlled trials in humans and studies in rodents and nonhuman primates. This review is based on a large number of expert reviews and commentaries and on some 50 recent studies in humans and animals that have not yet been included in published reviews. Expert opinion regarding the strengths and weaknesses of the major experimental systems and uncertainties associated with interpreting results is summarized. On the basis of our reading of this literature, we conclude that evidence from several types of studies, particularly studies in animals, suggests that, within the context of specific experimental designs, changes in brain concentrations of DHA are positively associated with changes in cognitive or behavioral performance. Additional experimental information required to conclude that a causal association exists is discussed, as are uncertainties associated with applying results from specific experimental designs to the question of whether infant formula should be supplemented with DHA.

Key Words: Long-chain polyunsaturated fatty acids • LCPUFAs • docosahexaenoic acid • DHA • linolenic acid • cognition • learning • memory • perinatal period • breastfeeding • formula feeding • essential fatty acids • n–3 fatty acids • brain • neurology • infants • childhood • rodent studies • nonhuman primate studies