In a recent paper in Acta Paediatrica, M. Aberg, N. Aberg, Brisman, Sundberg, Winkvist and Toren (2009) found that eating fish in adolescence predicted higher intelligence at age 18 (DOI:10.1111/j.1651-2227.2008.01103.x). Aberg et al. sent a questionnaire to thousands of Swedish 15-year-olds, requesting information about, amongst other things, their health, socioeconomic status and fish consumption. Three years later, the male participants completed an intelligence test as part of their military service conscription process. The authors were then able to assess the relationship between fish consumption at age 15 and intelligence at age 18 in nearly 4000 participants.
The results showed that teenage boys who ate fish more than once per week at age 15 scored higher on verbal and visuospatial intelligence three years later than boys who ate fish less often. This finding was stable across low and high education groups.
Why fish?
Fish contains both omega-3 and omega-6 fatty acids (specifically, docosahexaenoic acid and arachidonic acid). Omega-3 fatty acid is particularly significant. It cannot be synthesized by the human body, and must be obtained through our diet. It acts on the brain directly, and its presence during development is important for cognitive function. Deficits in omega-3 levels have been associated with risk for depression and schizophrenia, and with reduced cognitive function in several age groups. According to the American Heart Association omega-3 fatty acid supplements significantly reduce the numbers of deaths, heart attacks and strokes in patients with cardiovascular disease, and they are frequently suggested for people suffering from a wide array of inflammatory diseases such as arthritis, acne, diabetes and so on.
Omega-3 and omega-6 fatty acids have been part of the human diet throughout our evolutionary history. The ratio of omega-3:6 was likely about 1:1 for much of our evolutionary history; at present, the ratio in the North American diet is more like 1:10. Restoring the balance is easy; it requires consumption of more fish, especially fatty fish such as salmon, and other foods such as flax oil and walnuts.
