Omega-3 Fatty Acid - Mechanism of Action

Mechanism of Action

The 'essential' fatty acids were given their name when researchers found that they are essential to normal growth in young children and animals, though the modern definition of 'essential' is stricter. A small amount of n−3 in the diet (~1% of total calories) enabled normal growth, and increasing the amount had little to no additional effect on growth.

Likewise, researchers found that n−6 fatty acids (such as γ-linolenic acid and arachidonic acid) play a similar role in normal growth. However, they also found that n−6 was "better" at supporting dermal integrity, renal function, and parturition. These preliminary findings led researchers to concentrate their studies on n−6, and it is only in recent decades that n−3 has become of interest.

In 1964, it was discovered that enzymes found in sheep tissues convert n−6 arachidonic acid into the inflammatory agent called prostaglandin E₂, which both causes the sensation of pain and expedites healing and immune response in traumatized and infected tissues. By 1979, more of what are now known as eicosanoids were discovered: thromboxanes, prostacyclins, and the leukotrienes. The eicosanoids, which have important biological functions, typically have a short active lifetime in the body, starting with synthesis from fatty acids and ending with metabolism by enzymes. However, if the rate of synthesis exceeds the rate of metabolism, the excess eicosanoids may have deleterious effects. Researchers found that certain n−3 fatty acids are also converted into eicosanoids, but at a much slower rate. Eicosanoids made from n−3 fatty acids are often referred to as anti-inflammatory, but in fact they are just less inflammatory than those made from n−6 fats. If both n−3 and n−6 fatty acids are present, they will "compete" to be transformed, so the ratio of long-chain n−3:n−6 fatty acids directly affects the type of eicosanoids that are produced.

This competition was recognized as important when it was found that thromboxane is a factor in the clumping of platelets, which can both cause death by thrombosis and prevent death by bleeding. Likewise, the leukotrienes were found to be important in immune/inflammatory-system response, and therefore relevant to arthritis, lupus, asthma, and recovery from infections. These discoveries led to greater interest in finding ways to control the synthesis of n−6 eicosanoids. The simplest way would be by consuming more n−3 and fewer n−6 fatty acids.

They are required during the prenatal period for the formation of synapses and cell membranes. These processes are also essential in postnatal human development for injury response of the central nervous system and retinal stimulation.