The major groups of these essential polyunsaturated acids are: omega-3-fatty acid and omega-6-fatty acid.
These fatty acids are named by the location of the carbon-carbon double bonds within the fatty acid structure.
Omega 3's have the double bond between carbons 3 and 4 of the fatty acid;
Omega 6's have the double bond between carbon 6 and 7.
The main example of the omega-6-fatty acids is LINOLEIC ACID It is estimated that we need about one tablespoon of plant oil each day to meet our needs for LINOLEIC ACID. We easily meet this need with daily consumption of VEGETABLE OILS (CORN, SAFFLOWER, SOYBEAN, COTTONSEED, SESAME, OR SUNFLOWER), SEEDS, NUTS, AND WHOLE-GRAIN PRODUCTS.
IT CAN BE CONCLUDED MOST OF US CONSUME ENOUGH OMEGA-6-FATTY ACIDS - LINOLEIC ACID - DAILY. As far as the omega-6-fatty acids are concerned, the main example is LINOLENIC ACID and its derivatives EPA and DHA. Linolenic acid is found in fats and oils (canola, soybean, walnut, wheat germ, margarine and shortening made from canola and soybean oil);nuts and seeds (butternuts, walnuts, soybean kernels) and vegetables (soybeans).
The general consensus among nutritionists is that people do not consume enough omega-3-fatty acids. A MAJOR SOURCE OF OMEGA 3'S ARE FISH and SHELLFISH.
The fish suggested are: mackerel, salmon, bluefish, mullet, cablefish, menhaden, anchovy, herring, lake trout, sardines and tuna. It is estimated that fish, except for tuna, provide at least one gram of omega 3's in 100 grams of fish (3.5 ounces).
Tuna provides less but since it is more commonly consumed it is assumed it can be a significant contributor. EPA and DHA are derivatives of linolenic (omega 3's) found in fish oils.
Please note that the fish listed are noted as "fatty fish" since they have a high content of fish oils.
WHAT IS THE CONSUMER TO DO?
One suggestion is that since we eat enough omega 6's and not enough omega 3's is to increase our level of 3's intake. However, some research suggest our ideal intakes should be in a ratio of 1 (omega 3) to 4 (omega 6).
Another important aspect of this discussion is that nutritionists point out that omega 6's are needed to produce hormone-like substances in the body to improve immune and heart function.
The hormone-like substances are known as the PROSTAGLANDINS.
Prostaglandins are present in a number of tissues and have a variety of functions. Typically they exist in families that tend to occur in pairs that essentially produce opposite effects. For example, one pair would be PGE and PGF.
PGE typically produces opposite action to PGF.
Another pair is thromboxane and prostacyclin. Again, they typically produce opposite effects. Prostacyclin inhibits platelet aggregation while thromboxane stimulates platelet aggregation.
Hence, simply to state that omega 3's are important to allow production of prostaglandins does not answer the important question of which one(s) and what actions can be expected.
This particular topic - omega 3 and omega 6 - followed on the discussion of which type of fatty acid is best for our health.
Should our diets include oils with more polyunsaturated fatty acids and less monounsaturated and saturated fatty acids? Or should our diets include oils that contain primarily more monounsaturated fatty acids - such as olive oil.
Dr. Bill has lived through this argument. The general progress of arguments over the years has been: since olive oil is the one most affected by this discussion; and since it is highest in monounsaturated fatty acids; and since it cannot be shown that this oil is more dangerous or less dangerous than others that are higher in polyunsaturated fatty acids - the easiest conclusion has been to simply state that olive oil is good for your health and lets move away from discussions involving this aspect of fatty acids to one that involves omega 3's and omega 6's. The problem is that each time a "new danger on the block" is presented and then dropped and "a new danger" is presented - the consumer is perplexed. This is not the end of the story because the "newest danger" is trans fatty acids.
