Most fatty acids are non-essential, meaning the body can produce them as needed from other fats and some energy. However, in humans, at least two fatty acids are essential and must be consumed in the diet. An appropriate balance of essential fatty acids - omega-3 and omega-6 fatty acids - has been discovered to be important in reducing risk of some chronic diseases and conditions. Both of these “omega” long-chain polyunsaturated fatty acids are substrates for a class of eicosanoids known as prostaglandins which have uses throughout the human body; they are in some respects, hormones. The omega-3 eicosapentaenoic acid (EPA) (which can be made in the human body from the omega-3 essential fatty acid alpha-linolenic acid (LNA), or taken in through marine food sources), serves as a building block for series 3 prostaglandins (e.g. weakly-inflammation PGE3). The omega-6 dihomo-gamma-linolenic acid (DGLA) serves as a building block for series 1 prostaglandins (e.g. anti-inflammatory PGE1), whereas arachidonic acid (AA) serves as a building block for series 2 prostaglandins (e.g. pro-inflammatory PGE 2). Both DGLA and AA can be made from the omega-6 linoleic acid (LA) in the human body, or can be taken in directly through food. An appropriately balanced intake of omega-3 and omega-6 partly determines the relative production of different prostaglandins, which partly explains the importance of omega-3/omega-6 balance for cardiovascular health. In industrialised societies, people typically consume large amounts of processed vegetable oils that have reduced amounts of the essential fatty acids along with a too high ratio of omega-6 fatty acids relative to omega-3 fatty acids.

The conversion rate of omega-6 DGLA to AA largely determines the production of the respective prostaglandins PGE1 and PGE2. Omega-3 EPA prevents AA from being released from membranes, thereby skewing prostaglandin balance away from pro-inflammatory PGE2 made from AA toward anti-inflammatory PGE1 made from DGLA. Moreover, the conversion (desaturation) of DGLA to AA is controlled by the enzyme delta-5-desaturase, which in turn is controlled by hormones such as insulin (up-regulation) and glucagon (down-regulation). Because the amount and type of glucose and starch )plus some amino acid types) in food affect insulin, glucagon and other hormones, not only the amount of omega-3 versus omega-6 eaten but also the general composition of the diet, are implicated in general health regarding the essential fatty acids, inflammation (e.g. immune function) and mitosis (i.e. cell division).

Good sources of essential fatty acids include: fish, flax seed oils, hemp seeds and oils, soy beans, pumpkin seeds, sunflower seeds, and walnuts.[1]