Deficiencies in the body's reserve or production of essential fatty acids (EFAs) is a major contributory factor in a range of interrelated childhood disorders, including ADHD, dyslexia, asthma, allergies and even autism, and that EFA supplementation is of value in a significant number of cases. The overlap of clinical features between ADHD and, for example, dyslexia is around 30-50 per cent.
Fatty acids play an essential role in brain structure and function. Two of them, arachidonic acid (AA) and docosahexanoic acid (DHA), play a major role in the brain and eye, constituting 20 per cent of the dry weight of the brain and over 30 per cent of the retina. Two others, eicosapentaenoic acid (EPA) and dihomogamma linolenic acid (DGLA), are crucial for normal brain development, but play a more minor structural role.
The absolutely essential EFAs that cannot be synthesised by the body, and therefore must be supplied in the diet, are linoleic acid (omega-6 series, to which DGLA and AA belong) and alpha linolenic acid (omega-3 series, to which EPA and DHA belong). Both AA and DHA are termed longer chain polyunsaturated fatty acids (LC-PUFAs) and can usually be synthesised from their EFA precursors. The latter are critically important as they are precursors of a complex group of highly biologically active compounds, including prostanoids (prostaglandins, thromboxanes and prostacyclins, among others) and leukotrienes. These compounds perform numerous regulatory functions in the brain and the rest of the body.