Fatty acids are straight chains of carbon (C) atoms that have hydrogen (H) atoms attched. The beginning of the fatty acid is a methyl (CH3) group, and the end is a carboxyl (COOH) group. The carbon atoms are numbered from 1, at the beginning, to n, at the end.
Omega-3 fatty acids have a double bond between the third and fourth C atoms; omega-6 fatty acids have a double bond between the sixth and seventh:
Omega-3 fatty acid: CH3-CH2-CH=3DCH-CH2-CH2-CH2-CH2 … COOH
Omega-6 fatty acid: CH3-CH2-CH2-CH2-CH2-CH=3DCH-CH2 … COOH
We receive plenty of omega-6 fatty acids in our diets, from nuts, seeds and the oils derived from them, and from the fat of some animals, especially pigs. However, linolenic acid, the precurser of omega-3 fatty acids, is in only a few seeds and nuts, such as flax, hemp and pumpkin seeds, walnuts, and in the oils derived from them, and in soy oil. (Soy oil is also high in omega-6 fatty acids.) Algae are high in omega-3 fatty acids, and the leaves of many higher plants contain omega-3s, but in low concentrations. The common “weed” purslane (Portulaca oleracea) is relatively high in omega-3s. Many fish, especially herring, mackerel, wild salmon and sardines, are high in omega-3 fatty acids, as is fish oil.
People can have health problems if the ratio of omega-6:omega-3 exceeds 4:1. An ideal ratio is believed to be 3:1. Dr. Andrew Weil estimates that the modern diet of meat, fish, chicken and vegetable oils (many of the latter are rich in omega-6 fats) is between 20:1 and 40:1. Dr. Joseph Mercola says that grass-fed beef has a ratio of 3:1, while grain-fed beef is 20:1 or more. The Weston A. Price Foundation puts ratios of conventional eggs at up to 19:1, while eggs from organic, free-range chickens have a ratio of 1:1. The American Cancer Society says that studies of women with breast cancer have shown two to five times more omega-6 than omega-3 fatty acids in their systems.
According to Weil, researchers are studying deficiencies of omega-3 fatty acids for possible connections to such conditions as autism, attention deficit disorder and depression. He adds that brains that are deficient in DHA (docosahexaenoic acid, a very long-chain omega-3 fatty acid) “may be more susceptible to toxic injury that may result in degenerative diseases, such as Parkinson’s, ALS (amyotrophic lateral sclerosis or Lou Gehrig’s disease) and Alzheimer’s disease.” Because DHA is the main structural component of cell membranes in the brain, Weil says that its deficiency, especially during late fetal development and in infants, may weaken the central nervous system and thus impair learning ability, intelligence and other mental functions.
The American Cancer Society, “Omega-3 Fatty Acids,” at www.cancer.org/docroot/ETO/content/ETO_5_3X_Omega-3_Fatty_Acids.asp, July 13, 2003
Mercola, Dr. Joseph, “Why Grassfed Animal Products are Better for You,” at https://articles.mercola.com/sites/articles/archive/2001/08/29/beef-benefits.aspx, July 13, 2003.
Weil, Andrew, Eating Well for Optimum Health, Knopf, 2000
The Weston A. Price Association, www.westonaprice.org, July 13, 2003