The human body can manufacture most of the fats it needs, including cholesterol, saturated fatty acids, and unsaturated fatty acids. However, there are two families of fatty acids, the omega-6 and the omega-3 fatty acids, that are considered essential fatty acids. These fatty acids are essential because the parent omega-6 fatty acids, linoleic acids (LA) and the parent omega-3 fatty acids, alpha-linolenic acids (ALA), absolutely cannot be synthesized by the body and must be obtained from the diet or supplement.

Omega-3 fatty acids are essential fatty acids that are necessary from conception through pregnancy, and continue to support normal growth and development of infants. Throughout life, omega-3 fats aid in the prevention and treatment of heart disease, diabetes, arthritis, inflammatory disease and cancer. Omega-3 fatty acids also play an important role in protecting the health of the brain, eyes, and nervous system.

Omega-6 fatty acids are abundant in nature, and responsible for the inflammatory immune response.

Over 8,000 published clinical trials have unequivocally established that omega-3 fatty acids are important in human nutrition.

The primary source of omega-6 fatty acids in the human diet is linoleic acid (LA) from the oils of seeds and grains. Sunflower, safflower, soy, and corn oil are particularly rich in linoleic acid. Evening primrose oil, borage oil, and black current oil are unique due to their relatively high content of the health-promoting omega-6 fatty acids, gamma-linolenic acids (GLA).

The primary dietary source of omega-3 fatty acid is alpha-linolenic acids (ALA) from seeds and seed oils that are derived from plants such and flax, walnuts, and canola. Fish and fish oils are the richest sources of preformed long chain omega-3 fatty acids, Eicosapentaenoic Acid (EPA) and Docosahexaenoic Acid (DHA).

Humans have evolved consuming a diet that contained approximately equal amounts of omega-3 and omega-6 fatty acids. About 100 years ago, the industrial revolution introduced technology that allowed for the refining of vegetable and seed oils, which led to a dramatic increase in the consumption of omega-6 fatty acids among the industrialized countries. In addition, the introduction of animal feeds derived from gains rich in omega-6 fats have resulted in the production of meat, fish and eggs high in omega-6 and virtually void of omega-3 fats.

Today, in Western diets, the ratio of omega-6 to omega-3 fatty acids ranges from 20:1-30:1 instead of the pre-industrial range of 1-2:1. A large body of scientific evidence has established that a high intake of omega-6 fatty acids shifts the physiological state to one that promotes thrombosis, vasoconstriction, inflammation, and poor cellular health. The physiologic changes that result from high intake of omega-6 fats has been implicated in pathophysiology of heart disease, diabetes, autoimmune and inflammatory diseases (rheumatoid arthritis, multiple sclerosis, lupus, asthma, etc) depression, dementia and other chronic diseases.

Proven Benefits of Essential Fatty Acids
1. General health and well-being - A large body of scientific evidence suggests that aberrant inflammation underlies many common chronic diseases and is an obstacle to overall good health. The direct role of arachidonic acid-derived lipid mediators in promoting inflammation and EPA- and DHA- derived lipid mediators in regulating the resolution of inflammation has initiated much scientific interest in the influence of the omega-6:omega-3 ratio on human health 
2. Cardiovascular health - The American Heart Association (AHA) guidelines include recommendations for all Americans to consume omega-3 rich fish at least twice a weekly. For individuals with document heart disease, the AHA recommends 1 gram of EPA + DHA daily, and for patients with elevated triglycerides 2-4 grams of EPA + DHA daily. 
3. Cognitive health - Research has shown that omega-3 fats are necessary to develop, maintain, and protect structures of the central nervous system from conception through pregnancy and infancy and undoubtedly, throughout life. EPA and DHA contribute to cognitive health and development as well as mental well-being, behavior, learning, and mood. 
4. Anti-inflammatory - Inflammation is a normal protective physiological mechanism, but several factors in the Western diet, including excess omega-6 fat intake, and a relative deficiency of omega-3 fats, resulting in long-term inflammation. Omega-3 fatty acids from fish oil have anti-inflammatory effects due to the competition of EPA with AA n the cyclooxygenase and lipoxygenase pathways. In addition, omega-3s contribute to the formation of resolvins and protectins, which aid in the removal of inflammatory cells and restoration of tissue homeostasis once the need for inflammation is over. 
5. Pregnancy, infancy, and breast feeding - DHA is a significant structural component of the brain, eyes, and nervous system, which all are rapidly developing throughout the last trimester of pregnancy and the early stages of life. The fetus is dependent on its mother for DHA intake, which must be sufficient to maintain her own healthy levels and meet fetal demands, especially during the period of rapid nervous system development (last trimester - age 2)
6. Ocular health - Omega-3 fatty acids from fish oil help maintain healthy structure and function of ocular tissue. DHA is particularly important for the eyes, and attains it highest concentrations anywhere in the body within the eye tissue. Certain unique biochemical characteristics of DHA make it vital for the devolvement, function, and maintenance of the highly active, light-receiving cells found in the eye.

Consumers are often unaware that concentrated fish oil products are manufactured in two distinctly different molecular forms: one containing synthetic ethyl esters and the other containing the re-assembled natural triglyceride structure. In making a fish oil concentrate, the individual fatty acid are fish removed from the glycerol backbone; then they undergo molecular distillation that allows for the relative concentrations of EPA, DHA and other natural occurring fatty acids to be modified.

Once the desired amounts of fatty acids are achieved, a manufacture chooses from two distinctly different options. The first is to use enzymes to reattach the fatty acids to the glycerol backbone in a process known as "re-esterification." This process reassembles the fatty acids into the natural triglyceride structure.

The second, less costly manufacturing option is the react the free fatty acids with ethanol. This results in an "ethyl ester" fatty acid, a fatty acid that does not occur anywhere in the human diet. The majority of concentrated EPA and DHA products available to concerns today are in the ethyl ester form, perhaps due to the lower cost of production. Although the majority of fish oil products on the market contain the ethyl ester form of EPA and DHA, current research evidence suggest the triglyceride form is better for absorption and assimilation.