The Role Of Omega 3 Fatty Acids
As explained elsewhere, we include the two derivative omega 3 (n
-3) fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in the context of the term "Omega 3 EFA" in addition to ALA, the "official" n
-3 essential fatty acid.
To avoid confusion we will generally use the term "PUFA" rather than "EFA" when we talk about n
-3 fatty acids.
Why do we need Omega 3 PUFAs?
-3 PUFAs play an important role in maintaining our health by:
- Reducing inflammation
- Maintaining cell membranes
- Facilitating inter-cellular communication
- Controlling diverse metabolic functions via eicosanoid synthesis
- Regulating cholesterol and other blood plasma lipid levels
What roles do the different Omega 3 PUFAs play?
ALA, EPA and DHA are all key structural components of cell membranes via their inclusion in phospholipids.
ALA is used by the body to manufacture EPA and DHA via the n
-3 metabolic pathway.
EPA and DHA are present in high concentrations in brain and retina cell membranes. They are considered important for cognitive functions including memory and learning ability.
EPA is directly involved in the synthesis of certain eicosanoids that reduce inflammation. Eicosanoids are made "on-demand" by the body and impact a wide range of physiological processes.
EPA and DHA are precursors for resolvins and protectins, which perform an important anti-inflammatory role.
Find out about metabolic pathways
What specific health benefits can Omega 3 PUFAs provide?
Research published in February 2010 shows a clear connection between n
-3 PUFAs and the telomere mechanism involved in cellular aging.
-3 PUFAs exert a powerful preventative influence over the development of major degenerative diseases such as cardiovascular disease (CVD), cancer, diabetes, arthritis, depression and cognitive disorders.
Discover how omega 3 PUFAs can combat aging
Discover how omega 3 PUFAs can combat specific health problems
Physiology of Omega 3 PUFAs
Here is a high-level view of the main physiological functions of n
-3 PUFAs. A more comprehensive treatment can be found in any of the excellent books that have been published on this subject.
Much remains to be understood about ALA and its derivatives and the precise ways in which these n
-3 PUFAs are used by the human body, However, it is now widely accepted that they perform the following important roles:
-3 PUFAs help to maintain cell equilibrium. Together with n
-6 PUFAs, they are components of phospholipids. Phospholipids are present in cell membranes, where they promote fluidity and regulate the flow of substances into and out of the cell.
The Inner Life of the Cell: Get a powerful insight into the cell functions from this stunning animation from Harvard Medical School. The video includes nice visual representations of Lipid Bi-layers and Lipid Rafts, in which PUFAs participate. Visit http://multimedia.mcb.harvard.edu/anim_innerlife.html
By holding oxygen in the membrane, PUFAs prevent hostile organisms from invading the cell. They also facilitate the transport of oxygen and other essential nutrients into the cell and the expulsion of toxic substances.
-3 and n
-6 PUFAs compete for inclusion in the phospholipids used to construct cell membranes. The relative amounts of n
-3 to n
-6 PUFAs present in the phospholipids directly influence the proportion of n
-3-derived eicosanoids to n
-6-derive eicosanoids that are produced.
Regulation of plasma lipid levels
-3 PUFAs help to reduce levels of cholesterol and triglycerides in the blood (plasma lipids). This is considered an important factor in the development of atherosclerosis, which causes cardiovascular disease (CVD).
-3 PUFAs are incorporated into cell membranes, the flexibility that they provide needs to be balanced by the inclusion of rigid saturated lipid molecules, which are thus removed from the bloodstream.
-6 PUFAs also reduce overall blood cholesterol. However, it is believed that they reduce levels of beneficial HDL cholesterol as well as harmful LDL cholesterol. n
-3 PUFAs may therefore lead to a healthier ratio of HDL to LDL cholesterol.
-3 PUFAs play a vital role in inter-cellular communication, for example by facilitating signal transmission between brain cells. This is achieved via the elasticity that DHA contributes to the ion channels in brain cell membranes.
They play a similar role in retina cells, helping to maintain sharpness of vision. n
-3 PUFAs, especially EPA and DHA, are important for memory and cognitive functions and for maintaining a healthy central nervous system.
Prostaglandins, thromboxanes, leukotrienes and lipoxins are collectively known as eicosanoids. They act like hormones and are all derived from the 20-carbon PUFAs DGLA, AA (both n
-6) and EPA (n
-3). They perform a wide range of regulatory functions.
Prostaglandin production and anti-inflammatory actions
Prostaglandins are one of the important families that belong to the eicosanoid group of signaling molecules.
Series 1 and Series 2 prostaglandins are made using the n
-6 PUFAs DGLA and AA respectively. One type of series 2 prostaglandin, PGE2, is associated with increased blood clotting, high blood pressure and inflammation. These effects can cause a number of serious health problems.
Series 3 prostaglandins are made using the n
-3 PUFA EPA. The EPA component of PGE3 inhibits PGE2 production. It is therefore instrumental in combatting the health problems caused by PGE2.
Other anti-inflammatory mechanisms
EPA and DHA serve as precursors for powerful anti-inflammatory lipids called resolvins and protectins.
Energy production and distribution
-3 PUFAs facilitate oxidation via their double bonds as part of the energy generation cycle.
EPA and DHA regulate the expression of genes concerned with inflammatory activity and energy metabolism.