Fatty fish and fish oils are the primary sources of the omega-3 fatty acids, docosahexaenoic acid, or DHA, and eicosapentaenoic acid, or EPA. These omega-3 fatty acids play a critical role in proper brain growth and development. Deficiencies of these fatty acids have been linked to autism, dyslexia, attention deficient hyperactivity disorder, depression and anxiety according to registered dietitian Elizabeth Strickland in her book "Eating for Autism."
Brain Structure
DHA is a major component of the structure of the brain. According to a perspective article published in "The American Journal of Clinical Nutrition," omega-3 fatty acids, specifically DHA, accumulate rapidly during the last trimester of pregnancy and the first two years of life in the neuronal membranes. Lack of a high concentration of DHA in the brain has been linked to lower visual acuity, slower brain maturation and reduced brain processing.
Increase in Synapses
A paper published in "Metabolism" in 2008 suggests a primary benefit of DHA and EPA may be due to these omega-3s promoting the production of synaptic membranes. Synapses are the small gaps in between nerve cells that allow nerve transmission. Therefore, it is believed DHA may aid in brain growth and cognition by increasing neurotransmission.
Mercury Exposure
The longitudinal Seychelles Child Developmental Study is a continuous study examining the impact of exposure to mercury on brain development from high levels of maternal fish intake. A total of 229 mothers and their children were enrolled. Mothers completed a four day food dairy and food use questionnaire at 28 weeks gestation and hair samples were taken to determine mercury exposure. Developmental indexes were measured in infants at 9 and 30 months. The study found beneficial effects of DHA exposure on brain development, however these benefits were diminished or absent at higher mercury exposure.
Recommendations
The University of Maryland Medical Center suggests, that if you and your doctor decide supplementation is beneficial, dosing of supplements should be based on the amount of DHA and EPA in the supplement, not total fish oil. The Food and Nutrition Board has set the adequate level of the parent omega-3 fatty acid, alpha-linolenic acid or ALA, at 1.4 g per day for pregnant women and 1.3 g for breastfeeding mothers. The human body can normally produce DHA and EPA from the parent omega-3. While there is no specific requirement set for DHA and EPA, the Food and Nutrition Board indicates up to 10 percent of the adequate intake for ALA, around 130 to 140 mg, can be in the form of DHA and EPA combined. Children and pregnant women should avoid fish and fish oils that are known to contain mercury.
References
- "Eating for Autism"; Elizabeth Strickland MS, RD, LDN; 2009
- University of Maryland Medical Center: Omega-3 Fatty Acids
- "The American Journal of Clinical Nutrition"; Early Determinants of Development: A Lipid Perspective; Susan E. Carlson; May 2009
- "Environmental Research"; Varying Co-Efficient Function Models to Explore Interactions between Maternal Nutritional Status and Prenatal Methyylmercury Toxicity in the Seychelles Child Development Nutrition Study; Miranda L. Lynch, et al.; January 2011
- "Metabolism"; Synapse Formation and Cognitive Brain Development: Effect of Docosahexaenoic (DHA) and Other Dietary Constituents; R.J. Wurtman; October 2008
- Linus Pauling Institute at Oregon State University: Omega-3 Fatty Acids
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