Omega-3 and omega-6 fatty acids are “essential” – meaning we cannot make them on our own and must obtain them from our diet. In modern diets, the main source of omega-3s is the fat of cold-water fish such as salmon, sardines, herring, mackerel, and black cod (sablefish). The body needs two long-chain omega-3 fatty acids, (eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA]), both found in oily fish. It uses these as building blocks for hormones that control immune function, blood clotting, and cell growth as well as components of cell membranes. Vegetarian sources, such as walnuts, hemp seeds and flaxseeds contain a precursor, short-chain omega-3 (alpha-linolenic acid [ALA]) that the body must convert to EPA and DHA.
Omega-6 fatty acids are found in seeds and nuts and the oils extracted from them. Refined vegetable oils, such as soy oil, are used in most snack foods, cookies, crackers, salad dressings, sweets and fast foods. It’s estimated that an astounding 20 percent of the calories in the American diet come from soybean oil used in fast foods and processed foods.
The body also constructs hormones from omega 6 fatty acids. These tend to increase inflammation (an important component of the immune response), blood clotting, and cell proliferation, while those from omega-3 fatty acids decrease those functions. Both families of hormones must be in balance to maintain optimum health. It’s not that omega-3s are good and omega-6s bad; we need both.
Many nutrition experts believe that before we relied so heavily on processed foods, humans consumed omega-3 and omega-6 fatty acids in roughly equal amounts. But today, most North Americans and Europeans get far too many omega-6s and not enough omega-3s, a dietary imbalance that may explain the rise of such diseases as asthma, coronary heart disease, many forms of cancer, autoimmunity and neurodegenerative diseases. All are believed to stem from inflammation in the body. The imbalance between omega-3 and omega-6 fatty acids also may contribute to obesity, depression, dyslexia, hyperactivity and even a tendency toward violence. Consuming the essential fats in proper proportion may actually help relieve those conditions, according to Joseph Hibbeln, M.D., a psychiatrist at the National Institutes of Health and perhaps the world’s leading authority on the relationship between fat consumption and mental health.
A recent study from Tufts University has found that adults in their 70s with higher blood levels of omega-3s from fish had an 18 percent lower risk of unhealthy aging compared to those whose omega-3 levels were lowest. The study included 2,622 adults who were healthy at the outset and were followed from 1992 to 2015.
In addition, a Johns Hopkins’ study published in March 2019 found that dietary omega-3s appear to reduce asthma symptoms in children, while omega-6 fatty acids seem to worsen them. The study included 135 Baltimore inner city kids age 5 through 12. The youngsters were evaluated for their asthma symptoms, diet, and use of asthma medications at the study’s start and again 3 and 6 months later. Those with higher intake of omega-3s had milder reactions to indoor pollution and lower levels of white blood cells associated with inflammation compared to those whose omega-6 intake was higher. The latter had more severe symptoms and higher levels of white blood cells.
If you follow my anti-inflammatory diet, you should get a favorable ratio of these fatty acids. In general, you can cut down omega-6 intake by reducing consumption of processed and fast foods and polyunsaturated vegetable oils (corn, sunflower, safflower, soy, and cottonseed, for example). Use extra-virgin olive oil for cooking and in salad dressings. Eat more oily fish or take fish oil supplements. Those who avoid fish can take omega-3 supplements derived from algae. If you eat eggs, look for ones that are omega-3 fortified. Also eat walnuts, freshly ground flax seeds, and hemp seeds.
Andrew Weil, M.D.
Emily P. Brigham et al, “Omega-3 and Omega-6 Intake Modifies Asthma Severity and Response to Indoor Pollution,” American Journal of Respiratory and Critical Care Medicine, March 29, 2019, https://doi.org/10.1164/rccm.201808-147OC
Learn more: Here’s a video of Dr. Hibbeln talking about the omega-3 and omega-6 balance ratio at the 2010 Integrative Mental Health Conference.