How would this work?
The idea here is that ingesting fish oil supplements either boosts learning in typically developing children or helps children with developmental difficulties, such as ADHD, overcome behavioural problems.
Fish and shellfish contain Omega-3 fatty acids, which, along with Omega-6, are known as essential fatty acids (EFAs). ‘Essential’ because the body isn’t able to produce them itself, but rather relies on dietary intake: primarily seeds and grains in the case of Omega-6, which are over abundant in modern western diets[i]. EFAs are a vital part of brain chemistry: they make up around 20% of the dry weight of the brain[ii] and their presence is indicative of the quantity and balance of EFAs in our diets[iii]. Unsurprisingly, EFAs have a substantial impact on how the brain functions[iv].
What’s the evidence?
Despite the necessity of fatty acids for healthy brain function, the benefit of taking dietary supplements containing EFAs (usually Omega-3) is far from clear. There are remarkably few studies assessing the impact of supplements on typically developing, healthy children[v], and those that have been run are inconclusive. Some studies have reported beneficial effects on measures of attention[vi]; while others have found no notable benefits[vii],[viii],[ix]. Although differences between studies, such as type and duration of supplementation, make them hard to compare, if there were a substantial benefit to children’s learning, then it’s likely that this would be evident already.
Perhaps fish oils are just helpful for disorders?
Another line of enquiry is whether EFA supplements are beneficial for children with developmental disorders. A fairly solid link has been shown between low levels of EFAs in blood plasma and diagnoses of developmental disorders such as ADHD, Autism and dyslexia[x]. Three studies assessing the impact of EFA supplements have indicated that they may reduce ADHD-related symptoms in children with developmental disorders[xi], although even here changes are relatively small and inconsistent. Early indications are that research with this group of children may prove to be more fruitful than that with typically developing children, and there’s potential for productive work with young children and babies at risk of developmental problems.
When might fish oils be important?
This isn’t to say that EFAs don’t have beneficial effects on brain health. Fatty acids are vital during foetal growth and first two years of life[xii] when neurons are developing rapidly. High levels of supplemental EFAs may be especially important for premature infants[xiii] who, unlike full-term foetuses, are not exposed to fatty acids in the womb in the last weeks of gestation. Some preliminary results also suggest that supplemental EFAs may aid recovery from some mood disorders in adults as it’s thought that mood disorders may be associated with an underlying difficulty metabolising fatty acids[xiv]. Finally, in older age, low levels of Omega-3 are a risk factor for cognitive decline[xv].
A neuro-myth, but watch this space…
In conclusion, there’s no good evidence that EFA supplements help learning in typically developing healthy children. It seems that, in the absence of particular vulnerabilities, a normal diet is sufficient to provide the EFAs needed to support healthy brain function (we are estimated to need about 1-2% of calories from fatty acids[xvi]). However, supplements or diets rich in EFAs may yet be shown to support various neurological conditions in both adults and children, as well as supporting us at times of change in infancy or late adulthood. The verdict? For the majority of the population this is a neuro-myth.
For an impassioned look at the evidence, fish oil supplements is one of the topics Ben Goldacre covers in his excellent 2009 book Bad Science.
[vi] McNamara, R.K., Able, J., Jandacek, R., Rider, T., Tso, P., Eliassen, J.C., Alfieri, D., Weber, W., Jarvis, K., DelBello, M.P., Strakowski, S.M., Adler, C.M., (2010). Docosahexaenoic acid supplementation increases prefrontal cortex activation during sustained attention in healthy boys: a placebo-controlled, dose-ranging, functional magnetic resonance imaging study. The American Journal of Clinical Nutrition, 91, 1060-1067.
[vii] Osendarp, S. J. M., Baghurst, K. I., Bryan, J., et al. (2007) Effect of a 12-month micronutrient intervention on learning and memory in well-nourished and marginally nourished school-aged children: 2 parallel, randomized, placebo-controlled studies in Australia and Indonesia, American Journal of Clinical Nutrition, 86(4), 1082–1093.
[viii] Ryan, A. S. & Nelson, E. B. (2008). Assessing the effect of docosahexaenoic acid on cognitive functions in healthy, preschool children: a randomized, placebo-controlled, double-blind study, Clinical Pediatrics, 47 (4), 355–362.
[ix] Kirby, A., Woodward, A., Jackson, S., Wang, Y., & Crawford, M. A. (2010). A double-blind, placebo controlled study investigating the effects of omega-3 supplementation in children aged 8-10 years from a mainstream school population. Research in Developmental Disabilities, 31, 718-730.
[xii] Eilander, A., Hundscheid, D. C., Osendarp, S. J., Transler, C., & Zock, P. L. (2007). Effects of n-3 long chain polyunsaturated fatty acid supplementation on visual and cognitive development throughout childhood: A review of human studies. Prostaglandins Leukotrienes and Essential Fatty Acids, 76, 189–203.
[xiii]Birch, E. E., Garfield, S., et al. (2007). Visual acuity and cognitive outcomes at 4 years of age in a double- blind, randomized trial of long-chain poly-unsaturated fatty acid-supplemented infant formula. Early Hum Dev 2007;83:279–284.
[xiv] Freeman, M. P., Hibbeln, J. R., Wisner, K. L., Davis, J. M., Mischoulon, D., Peet, M., Keck, P. E., Marangell, L. B., Richardson, A. J., Lake, J., & Stoll, A. L. (2006). Omega-3 fatty acids: Evidence for treatment and future research in psychiatry. Journal of Clinical Psychiatry, 67 (12), 1954-1967.
[xv] Conquer, J. A., Tierney, M. C., Zecevic, J., Bettger, W. J., & Fisher, R. H. (2000). Fatty acid analysis of blood plasma of patients with Alzheimer’s disease, other types of dementia, and cognitive impairment. Lipids, 35 (12), 1305-1312.