The following is a condensed refresher, mainly from this page.
EFAs (essential fatty acids) are:
- LA (linoleic acid) [n-6, Omega-6]
- ALA or LNA (alpha linolenic acid) [n-3, Omega-3]
Essential because the body cannot make them; therefore, they must come into the body via the diet. The value of EFAs in the body can be reviewed here.
Non-EFAs (non-essential fatty acids) include:
- EPA (eicosapentanoic acid) necessary for the circulation system
- DHA (docosahexanoic acid) necessary for the brain, heart, and eyes
- SDA (stearidonic acid) necessary to increase EPA concentrations
Non-essential because the body can make them from omega-3 ALA
- AA [ARA] (arachidonic acid) a necessary structural component and precursor that can have antagonistic effects
- GLA (gamma-linolenic acid) necessary to prevent certain skin conditions
Non-essential because the body can make them from omega-6 LA
Conversion Process1, 2
Omega-3 conversion process is as follows:
- ALA converts to the enzyme Delta-5-desaturase.
- Delta-5-desaturase converts to SDA.
- SDA elongates and converts to EPA.
- EPA elongates and converts to DHA and the prostaglandin PGE3.
(EPA is the precursor for series-3 prostaglandins and thromboxanes and series-5 leukotrienes).
Omega-6 conversion process is as follows:
- LA converts to the enzyme Delta-6-desaturase.
- Delta-6-desaturase converts to GLA
- GLA converts to DGLA
- DGLA converts to the prostaglandin PGE1 and AA.
- AA converts to the prostaglandin PGE2.
Marine sources (oily fish and algae) contain the converted or long-chain forms of DHA and/or EPA.
Plant-based sources contain the parent (precursor) or medium-chain forms, ALA and LA. However, land-based animals used to be good sources of these EFAs, which were concentrated in the brain, eyeballs, adrenal glands, and testes. This explains one reason why primitive tribes prized these organs and ate them raw immediately after a kill. Because of domestication, pollution, and feed, this is no longer the case.3 Through processing and refining of oilseed plants, all but scant amounts of the omega-3s (ALA) are lost, leaving only the omega-6 (LA) content. Because there is too much LA in the average diet and too little ALA, health problems have skyrocketed.
ALA, omega-3, is found in such plant-based oils as:
- Chia seed (63.8%)4
- Flaxseed (56.4%)5
- Hemp seed (20%)6
- Canola (9.4%)7
- Walnuts (3-14%)8
- Soybean (6.8%)9
- Pumpkin seed (0-15%10
Dark green leafy plants contain only a little oil, but what there is consists of over 50% ALA. Wild purslane is the richest green leafy plant source.
EPA and/or DHA are found almost exclusively in aquatic plants and oily fish. The highest levels come from salmon, tuna, sardines, trout, and corvina, if they eat phyto-plankton. EPA and DHA supplements are also readily available, but the caution is that these two preformed EFAs are easily oxidized, thereby causing more health problems than they fix; adding an antioxidant, as vitamin E, will help to offset this problem to a certain extent maybe.
SDA is found mainly in black current seed oil and is the biochemical percursor to EPA and DHA. While it has not been studied nearly as much as the other two, what has been done is to show health-benefit potential. SDA and GLA work together to alleviate various skin diseases.
LA, omega-6, is found in most oils, especially those from safflower, sunflower, hemp, soybean, walnut, pumpkin, sesame, and flax. The richest source of LA is a non-processed safflower oil – which is hard to obtain (see oil processing). New genetic varieties of high oleic safflower and sunflower oils now contain only small quantities of LA, whereas before, they were once the richest sources.
GLA is said to be the only good fatty acid form to come out of omega-6 fatty acid because it is almost identical to ALA. The only difference between the two is where one double bond is placed on the chain. This may seem like a small difference; but to the body, it is a major distinguishing factor that impacts various funtions. Since there are many reasons why GLA cannot be converted from LA in the body, it is wise to obtain it from oils where it is already present.
Besides being formed from LA, GLA is also found in such oils as borage [aka starflower] (20-26%), black currant (14-19%), evening primrose (7-10%)11, hemp seed (4% plus 2% SDA and 9% omega-9)12, as well as spirulina and walnuts.
AA is found only in animal fats and should not be confused with arachidic acid found in peanuts. AA, as well as DHA, is crucial to the optimal development of the brain and eyes. Since these are non-essential fatty acids, the body can make AA from LA and DHA from ALA.
- 1Vasquez. Integrative Orthopedics: Concepts, Algorithms, and Therapeutics. 2004.
- 2Enerex. Omega 6 & 3 Essential Fatty Acids: (Evening Primrose and Fish Oils).
- 3Erasmus. Fats that Heal, Fats that Kill: The complete guide to fats, oils, cholesterol and human health. Alive Books, 1993, pages 208, 219, 223-235.
- 4Coates and Ayerza. “Commercial production of chia in northwestern Argentina.” Journal of the American Oil Chemists Society 75(10):1417-20. 1998.
- 5Manitoba Agriculture.. 2001. “Manitoba Grains & Oilseeds Industry Profiles 2001.”
- 6Hemp Oil Canada.
- 7Government of Canada. 2001. “Quality of 2001 Western Canadian Canola.”
- 8USDA. 1986. “Provisional table on the content of omega-3 fatty acids and othr fat components in selected foods.” Publication HNIS/PT 103.
- 9Raper, Cronin, and Exler. “Omega-3 fatty acid content of the US food supply.” Journal of the American College of Nutrition 11:304-308. 1992.
- 10Erasmus. Fats that Heal, Fats that Kill: The complete guide to fats, oils, cholesterol and human health. Alive Books, 1993, page 237
- 11WholeHealthMD. “Evening Primrose Oil.”