The ABCs of EFAs|
|LA||linoleic||(omega)-6||corn, safflower, sesame, sunflower oils|
|GLA||gamma-linolenic||(omega)-6||primrose, borage, black currant seed oils|
|AA||arachidonic ||(omega)-6||animal meat, milk, eggs, squid, warm-water fish|
|ALA||alpha-linolenic||(omega)-3||flax, canola, pumpkin, walnut oils|
|EPA||eicosapentaenoic||(omega)-3||cold-water fish, some algae|
some algae, warm-water fish (although in lower amounts than cold-water fish), cold-water fish (anchovy, chinook salmon, herring, mackerel, albacore tuna and Pacific halibut)
The ideal ratio of omega-6:omega-3 fatty acid consumption
is 1:1. The average American diet pushes that ratio to 20:1 or 30:1. Where have the omega-3 fatty acids gone? Blame it on altered eating habits:
Fatty Acid Metabolism
- increased consumption of corn, sunflower and sesame oils;
- hydrogenation of oils in food processing;
- decreased fish consumption;
- loss of cereal germ in modern milling practices;
- increased sugar consumption, which interferes with enzymes that synthesize fatty acids;
- increased consumption of trans fatty acids (such as mar-
garine, deep-fried foods and prepared foods), which
interfere with fatty acid synthesis as well.
The two families of essential fatty acids give rise to separate sets of LCPs, and there is no interconversion between families. If an excess of omega-6s exist, for example, the excess cannot be converted into omega-3s. Furthermore, the same set of enzymes must convert both linoleic (omega-6) and linolenic (omega-3) fatty acids into their respective LCPs. If more dietary omega-6s than omega-3s are available, the enzymes will generate more gamma-linolenic acid (GLA), dihomogamma-linolenic acid (DGLA) and arachidonic acid (AA). If the diet is high in saturated fats and low in oils--that is, high in animal fat, butter, margarine and other hydrogenated fats--more AA will be directly produced, bypassing GLA and DGLA formation. This can have serious consequences for immune and cardiovascular function.
Source: Simopoulos AP, Robinson J. The omega plan.
New York: HarperCollins Publishers; 1998.