An essential fatty acid and the most abundant ω-3 fatty acid in neural tissues, especially in the retina and brain; constitutes as much as 40% of the total PUFA pool in retinal and neuronal membranes; dietary supplementation via fish oil inhibits the progression of atherosclerosis and delays photoreceptor degeneration in retinitis pigmentosa; deprivation in neonatal rats causes developmental defects and can lead to hypertension