The human body can use carbohydrate, fat, or protein to synthesize almost all the fatty acids it needs. However, the two exceptions are polyunsaturated fats, linoleic and linolenic acids, classified as essential because they cannot be made from other substances in the body or from each other. For that reason, Essential Fatty Acids (EFA) must be provided by your diet. Three important fatty acids are omega-3, omega-6, and omega-9. Food oils often contain a combination of these building blocks, which may account for the mixed results observed in people consuming them.

* Omega-3 fatty acids are categorized as alpha-linolenic acid (sources include canola oil, soybeans, flaxseed, fish, poultry) and docosahexaenoic and eicosapentaneoic acids (sources are oily fish and breast milk). Studies have indicated that vegetable oils containing alpha-linolenic acids and fish oils which include docosahexaenoic(DHA) and eicosapentaenoic(EPA) acids, reduce triglycerides and are heart protective. Fish itself has other substances that appears to have many benefits, such as supporting brain's thinking part, the cerebral cortex, and eye's main vision center, the retina.

* Omega-6 fatty acids are categorized as linoleic, or linolic, acid (sources are flaxseed, corn, soybean, and canola oil, seeds, nuts, whole grain products). Many hydrogenated fats are made from oils rich in omega-6 fatty acids. The majority of people consume enough of linoleic acid.

* Omega-9 fatty acids(source is olive oil)

Research indicates that, in a healthy balance, all of these fatty acids are indispensable to life. A deficiency of an essential fatty acid in the diet leads to noticeable changes in cells resulting in symptoms of reproductive failure, skin abnormalities, and kidney and liver disorders.

Consider that overdoses, just like underdoses, may also impair immune function, elevate LDL cholesterol, alter blood lipids and blood clotting, and worsen Type II diabetes. Moreover, fish oil naturally contains high levels of the two most potentially toxic vitamins, A and D. So, everything is good in moderation.

Some researchers believe, however, that our current Western diet now contains an unhealthy ratio of omega-6 to omega-3 of fatty acids. Authorities report that diets too high in linoleic acid (omega-6) may cause the metabolism to be sluggish and promote a tendency to storing body fat. Currently most Americans eat a dietary ratio of omega-6 to omega-3 fatty acids that falls between 20:1 and 50:1. The optimal ratio is most likely closer to the original ratio of 1:1, according to studies on ancient diets. For most of us this means greatly reducing the omega-6 fatty acids we consume and increasing the amount of omega-3 fatty acids. You can easily accomplish this by eating more fish and reducing your consumption of vegetable oils. The bottom line, then, is to try to obtain a better balance of fatty acids without consuming too many calories.