Fish, especially oily fish, is the main dietary source of omega- 3 fatty acids. Suggested benefits of these essential fatty acids include roles in cognition, brain development, visual acuity, ADHD, autism, behaviour and intelligence.
What role do omega-3 fatty acids play in brain development and visual acuity?
Omega-3 fatty acids have crucial roles to play in brain and eye development. Docosahexaenoic acid (DHA) constitutes 25% of brain fatty acids1 (see references below) and has an important role to play in brain development in late pregnancy.2 DHA is important in vision, accounting for 50% of retinal fatty acids.3 Sub-optimal cognitive function and vision have been associated with poor DHA status during foetal development.4, 5 Despite criticism one study showed that supplementation with omega-3 fatty acids during pregnancy and lactation improved intelligence quotient (IQ) at four years of age, but no improvement was found at seven years of age.6, 7 Further research into the potential benefit of prenatal omega-3 fatty acid supplementation for child mental development is needed.8
What role do omega-3s have in ADHD?
ADHD affects around 1.4% of UK children 9, although it is often reported as more prevalent than this. Children with ADHD, who have lower serum levels of omega-3 fatty acids, have been shown to have more behavioural problems.10 A number of studies show positive benefits to omega-3 fatty acid supplementation, with improvements seen in behaviour and reading ability.11 Supplementation with high doses of eicosapentaenoic acid (EPA) balanced with DHA and gamma-linoleic acid (GLA) may be an effective treatment for ADHD, if taken for at least three to four months. It is still unclear whether supplementation can be used as an alternative to conventional ADHD treatment, but as fish oils are considered relatively safe and are deemed beneficial to general health they offer a promising complementary approach to standard treatments.12,13 More research is needed to establish which children with ADHD are likely to have the best response to fish oil supplementation and the optimum dose required.
Do omega-3s have a role in autism?
28% of children with autism use fish oil supplements.14 Many studies report positive outcomes for the use of omega-3 fatty acids in autism. Autistic children supplemented with fish oils were found to have reduced hyperactive behaviour.15 Unfortunately many of the studies in this area are small or poorly controlled, so there is a need for more large well conducted randomised controlled trials.16
What about omega-3s in school-aged children?
Although many studies have focussed on children with learning or behaviour disorders, some studies have looked at using omega-3 supplements in normal, healthy children. Omega-3 supplementation has not so far been shown to have a major impact on mental performance tests but there have been some positive outcomes - improved DHA and EPA status, improvements in immune function, better memory and improvements in verbal learning, comprehension and vocabulary acquisition tests.17, 18,19 One study showed reductions in inattention and undesirable class behaviour.20 A recent review of the evidence suggests that although consistent conclusions on the treatment effects of DHA are lacking, DHA supplementation did cause improvements in either cognition or behaviour in half the studies reviewed. Fish oils may have an important role in school performance.21
References
1. Crawford MA et al., The long chain metabolites of linoleic and linolenic acids in liver and brain in herbivores and carnivores . Comparitive Biochemistry and Physiology, 1976. 54: 395-401
2. Clandinin MT et al., Do low weight infants require nutrition with chain elongation – desaturation products of essential fatty acids? Progress in Lipid Research, 1982. 21: 901-904
3. Stinson AM et al., Fatty acids and molecular species compositions of phospholipids and diacylglycerols from rat retinal membranes. Experimental Eye Research, 1991. 52: 213-218
4. O’Connor DL et al., Growth and development in preterm infants fed long- chain polyunsaturated fatty acids: a prospective, randomised controlled trial. Pediatrics, 2001. 108: 359-371
5. Innis SM & Friensen RW.,Essential n-3 fatty acids in pregnant women and early visual acuity maturation in term infants. Am J Clin Nutr, 2008. 87(3):548-57
6. Helland IB et al., Effect of supplementing pregnant and lactating mothers with n-3 very-long-chain fatty acids on children's IQ and body mass index at 7 years of age. Pediatrics. 2008. 122:e472–9
7. Helland IB et al., Maternal supplementation with very-long-chain n-3 fatty acids during pregnancy and lactation augments children's IQ at 4 years of age. Pediatrics. 2003;111:e39–44
8. Leung BMY et al., Does prenatal micronutrient supplementation improve children's mental development? A systematic review. BMC Pregnancy Childbirth. 2011 11:12 doi:10.1186/1471-2393-11-12
9. Russell G et al., Prevalence of parent-reported ASD and ADHD in the UK: findings from the Millennium Cohort Study. J Autism Dev Disord, 2014. 44(1):31-40
10. Antalis CJ et al., Omega-3 fatty acid status in attention-deficit/hyperactivity disorder. Prostaglandins Leukot Essent Fatty Acids, 2006. 75(4-5):299-308
11. Johnson M et al., Fatty acids in ADHD: plasma profiles in a placebo-controlled study of Omega 3/6 fatty acids in children and adolescents. Atten Defic Hyperact Disord, 2012. 4(4):199-204
12. Richardson AJ. ,Omega-3 fatty acids in ADHD and related neurodevelopmental disorders. International Review of Psychiatry, 2006. 18(2): 155–172
13. Bloch MS & Quwasmi, A., Omega-3 Fatty Acid Supplementation for the Treatment of Children with Attention-Deficit/Hyperactivity Disorder Symptomatology: Systematic Review and Meta-Analysis. J Am Acad Child Adolesc Psychiatry. 2011. 50 (10):991-1000
14. Huxham L. Feeding problems and current dietary practices in children with autism spectrum disorder in England. Thesis for Master of Nutrition at the University of Stellenbosch. 2012
15. Amminger GP et al., Omega-3 fatty acids supplementation in children with autism: a double-blind randomized, placebo-controlled pilot study. Biol Psychiatry, 2007, 61 551−3
16. James S et al., Omega-3 fatty acids supplementation for autism spectrum disorders (ASD). Cochrane Database Syst Rev., 2011. 9;(11):CD00799
17. Osendarp SJM et al., Effect of a 12-mo 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 Am J Clin Nutr, 2007. 86 (4) 1082-1093
18. Mazurak, VC et al., Long-chain Polyunsaturated Fat Supplementation in Children With Low Docosahexaenoic Acid Intakes Alters Immune Phenotypes Compared With Placebo. Journal of Pediatric Gastroenterology & Nutrition, 2008. 46: 570-579
19. Ryan AS & Nelson EB., Assessing the effect of Docosahexaenoic acid on cognitive functions in healthy, preschool children: a randomized, placebo-controlled, double-blind study. Clin Pediatr (Phila), 2008. 47 (4): 355-362
20. Kirby A et al., 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, 2010. 31: 718-30
21. Kuratko CN et al., The relationship of Docosahexaenoic Acid (DHA) with Learning and Behavior in Healthy Children: A Review. Nutrients, 2013. 5(7):2777-2810
