DHA Effects in Brain Development and Function
The brain has a unique fatty acid composition, and DHA is quantitatively the most important omega-3 fatty acid in the brain. The DHA fatty acid has consistently been shown to have unique and indispensable roles in the neuronal membrane.
Nutrition plays an important role in brain development and cognitive function. Intake of EPA and DHA is considered particularly important for neuronal development during early infancy where a substantial amount of DHA is accumulated in the brain. This accumulation of DHA continues throughout childhood, especially in the frontal cortex, which is involved in cognitive and socioemotional functions, which continue to develop until early adulthood. Worldwide oily fish are currently the primary dietary source of EPA and DHA. A number of randomised clinical trials of oily fish intake have demonstrated benefits for cognition, learning and/or mental health in pre-school children, in primary school children, and in adolescents. Two important points:
- All of these studies were conducted in Scandinavian countries where baseline levels of omega-3 PUFAs are higher than the worldwide average – benefits were still seen where levels were further increased.
- The improvements in cognition and mental health were most marked in those with the best adherence to the study diet – i.e. in those children whose oily fish intake actually increased, and in whom blood levels of DHA increased.
Inflammation in the brain is beneficial to maintain organ homeostasis in response to infection. Brain inflammation involves microglial cells, the resident macrophages of the central nervous system. When activated, these cells produce pro- and anti-inflammatory cytokines. However, when the production of proinflammatory cytokines is sustained, these molecules become neurotoxic, leading to neuronal damage involved in many brain pathologies. Hence, limiting inflammation is of great importance. A large number of studies support the hypothesis that long chain omega 3 fatty acids or their products are candidates for limiting neuroinflammation.
Many studies evaluating the relationships between long-chain omega-3 fatty acids intake and risk of dementia or Alzheimers disease suggest that there was may be a potential protective effect of long-chain omega-3 fatty acids on incidence of dementia and Alzheimers disease.
In the last 20 years, epidemiologic studies have linked dietary PUFAs in the pathophysiology of mood disorders. In particular, dietary intake of food rich in n-3 LC-PUFAs is associated with reduced prevalence of major depression, postpartum depression, or bipolar disorder.