Mammals, including man, are unable to produce the essential fatty acid LINOLEIC acid (LA - omega-6), which must be supplied from foods. The body converts LA to gamma-LINOLENIC acid (GLA - omega-6) and ultimately to prostaglandins, hormone-like substances which help to regulate inflammation, blood pressure and many other functions in the body. GLA may be converted into DGLA (dihomogamma-linolenic acid) if adequate supplies of magnesium, zinc and vitamin B3, B6 and C are available. GLA may also be converted into ARACHIDONIC acid (AA - omega-6). Arachidonic acid is also considered to be essential, but only when linoleic acid is deficient. All these fatty acids are present in phospholipids, which help maintain the structure and function of cellular membranes. However, not all these omega-6 fatty acids behave in the same way. For example, LA and AA are often considered "unhealthy", because they promote various types of inflammations in the body, whereas GLA reduces them.

The omega-6 fatty acids are found in the seeds of plants and the oils produced from them. Corn, safflower, sunflower and soybean oil and wheat germ are all high in linoleic acid. The more "exotic" sources of omega-6 fatty acids include, borage oil, black current oil and evening primrose oil.

Why are omega-6 fatty acids considered "bad"? The presence of such substances as prostaglandins, leads researchers to believe, that too little linoleic acid is bad and too much or rather a dietary imbalance is also bad. The definition of too much or imbalance is the difficult part and will depend on the intake of saturated fats and carbohydrates, both of which increase the need for linoleic acid intake.

The third essential fatty acid is LINOLENIC acid. There are TWO. We have "met" gamma -Linolenic acid (GLA - omega-6) above, but there also is the more important, alpha-Linolenic acid (ALA), which is an omega-3 fatty acid. From linolenic acid can be produced EPA (eicosapentaenoic acid) and DHA (docasahexaenoic acid) which are important in the membranes of the retina and brain and modify platelet function and inflammatory responses. Both DHA and EPA are omega-3 fatty acids. DHA and EPA are synthesized by photoplankton and algae and are thus abundant in seafood. The richest sources are mackerel, anchovies, herring, salmon, sardines, lake trout, tuna and Atlantic sturgeon. In plants the highest levels are found in walnuts, flaxseeds (flax oil), rapeseed (canola oil) and purslane.

Now as to the "sisters, cousins and aunts".
Obviously the sisters are omega-6 and omega-3. We need them *both*. The ratio of omega-6 to omega-3 in American cell membranes is 4:1, whereas that in the Japanese is 1:1 and the Eskimos (with very low chronic disease rates) 1:4. The intake of omega-6 to omega-3 in Americans is 10:1, whereas in Eskimos it is 1:3. The World Health Organization (WHO) seems to indicate a satisfactory intake would be between 5:1 to 10:1, whereas Canadians are advised that the ratio should be between 4:1 and 10:1. The ratios (omega-6:omega-3) in some cooking/salad oils are: flaxseed 1:3; canola 2:1; extra virgin olive oil 8:1; soybean oil 8:1 and corn oil 60:1.

Now the "cousins" are Vitamin E and selenium. It is very important for the best absorption of the unsaturated fatty acids, that Vitamin E and selenium be present, which they are in most foods containing these fatty acids. Only when one is taking highly processed supplements, may they sometimes be deficient.

The "aunts" are carbohydrates, Vitamin D (and calcium), the Vitamin A system and fats, both saturated and unsaturated.