Evolutionary Aspects of Diet: The Omega 6/Omega 3 Ratio and the Brain.

Key Findings:

Omega 3 fatty acids have health benefits in cancer, inflammatory bowel disease, rheumatoid arthritis, psoriasis, and mental health. Omega 3 fats lead to (1) a decreased production of prostaglandin E2 (PGE2) metabolites; (2) a decrease in thromboxane A2, a potent platelet aggregator and vasoconstrictor; (3) a decrease in leukotriene B4 formation, an inducer of inflammation and a powerful inducer of leukocyte chemotaxis and adherence; (4) an increase in thromboxane A3, a weak platelet aggregator and a weak vasoconstrictor; (5) an increase in prostacyclin PGI3, leading to an overall increase in total prostacyclin by increasing PGI3 without a decrease in PGI2. Both PGI2 and PGI3 are active vasodilators and inhibitors of platelet aggregation; and (6) an increase in leukotriene B5, a weak inducer of inflammation and a weak chemotactic agent. Omega 3 deficiency in rat brain is associated with reduced biosynthesis of catecholamines and decreased learning ability, with a lower synaptic vesicle density in the hippocampus. Omega 3 improves memory related learning due to increased neuroplasticity of the neural membranes. These fats may affect cognition functions, mood and emotional states and may act as a mood stabilizer. The author makes the strong argument that the balance between LA and ALA and their PUFA metabolites is vital. The omega 6 and omega 3 PUFA metabolites should be reduced. A high omega 6 proportion is largely made up by LA and too high for normal growth and development. The ratio of omega 6/omega 3 fatty acids in the brain between 1:1 and 2:1 is in agreement with the data from the evolutionary aspects of diet, genetics.

ABSTRACT:

Several sources of information suggest that human beings evolved on a diet that had a ratio of omega 6 to omega 3 fatty acids (FA) of about 1 to 1, whereas today, Western diets have a ratio of 10 to 1 to 20 to 25/1, indicating that Western diets are deficient in omega 3 FA compared with the diet on which humans evolved and their genetic patterns were established. Omega 6 and omega 3 FA are not interconvertible in the human body and are important components of practically all cell membranes. Studies with nonhuman primates and human newborns indicate that docosahexaenoic acid (DHA) is essential for the normal functional development of the brain and retina, particularly in premature infants. DHA accounts for 40 percent of the membrane phospholipid FA in the brain. Both eicosapentaenoic acid (EPA) and DHA have an effect on membrane receptor function and even neurotransmitter generation and metabolism. There is growing evidence that EPA and DHA could play a role in hostility and violence in addition to the beneficial effects in substance abuse disorders and alcoholism. The balance of omega 6 and omega 3 FA is important for homeostasis and normal development throughout the life cycle. (Authors abstract)