Evolutionary aspects of diet: The omega-6/omega-3 ratio and how this affects the brain

Article at a glance

  • Several sources of information suggest that humans evolved on a diet that had a ratio of Omega-6 to Omega-3 fatty acids of about 1:1; today’s Western diet has a ratio of 16:1 indicating that the typical diet today is deficient in Omega-3s compared to the diet on which humans evolved.
  • This imbalance between Omega-6 and Omega-3 may negatively impact brain health, memory, mood, inflammation, mental health, and normal growth and development.
  • The balance of Omega-6 and Omega-3 fatty acids is important for normal development and optimal health throughout the life cycle and a ratio of Omega-6: Omega-3 of 1:1 would improve overall health outcomes and should be the target for human health.    

The interaction between genetics and our actual and nutritional environment is the foundation of all health and disease. Genetically speaking, humans today have changed very little from our ancestors in the Paleolithic period, yet major changes have taken place in our diet. Studies on the evolutionary aspects of the diet indicate that one of the most significate changes that have taken place include increases in saturated, trans, and Omega- 6 fatty acid intake, and decreases in Omega-3 fatty acid intake. Evidence suggests that humans today living in a nutritional environment that differs so significantly from which our ancestors evolved can cause problems for our overall health and longevity. 

Both Omega-6 and Omega-3 fatty acids influence gene expression and health, and the while they are both necessary for optimal wellness, the balance between the two is an important determinant in normal growth, development, mental health, and aging. For most of our existence, the balance between Omega6: Omega-3 was 1:1; whereas, today in Western societies the ratio is about 16:1.

An imbalance of Omega-6 and Omega-3 has been shown to cause an overproduction of proinflammatory molecules which may be involved in several health conditions. Evidence indicates that diets with a high Omega-6: Omega-3 ratio enhance the risk for depression, mental health conditions, and inflammatory disease. High amounts of Omega-6 fatty acids have also been associated with shorter telomere lengths, which in turn, are associated with aging, cancer, and coronary heart disease. 

 Increasing two types of Omega-3 fatty acids, EPA and DHA, in the diet has been demonstrated to have several brain and health benefits in animal and human studies including improved memory-related learning ability, improved cognitive performance, and decreased risk of cardiovascular disease. Increasing Omega-3 intake has also been shown to have positive effects on dementia, schizophrenia, mood, and other central nervous system diseases. Omega-3s have even been shown to resolve inflammation which is at the base of many chronic diseases such as obesity, diabetes, arthritis, mental illness, cancer, and autoimmune diseases.

This study concludes that the balance between Omega-6 and Omega-3 in the diet is vital and the ratio between the two is more important that the absolute amounts consumed. The brain is one of (if not the) most outstanding organ in our biology, and we can improve our nutritional environment to prioritize brain growth, development, function, and maintenance. Therefore, an Omega-6: Omega-3 ratio of 1:1, or close to it, should be the target for human health. The best way to accomplish this is to simply increase Omega-3 intake.

Stacy Cappadona MS, RD, CSCS received her BS in Exercise Science and MS in Exercise Physiology and Sports Nutrition from Florida State University. She has worked with athletes of all ages, active duty military personnel, and is now serving people globally through virtual coaching programs as the Founder of Stacy Rae Wellness.