Both the omega-6 and omega-3 fatty acids belong to a group of polyunsaturated fats called 'essential' because they are necessary to life and to health yet we cannot make them in the body - they must be obtained from diet. They cannot be inter-converted and both must be present in the diet in a proper balance for good health.
Their differences lie in their chemical structure and their roles in the body.
As polyunsaturated fatty acids, both the omega-6 and the omega-3 families have more than one double bond in the carbon chain. All fatty acids in the omega-6 family contain their first double bond between the 6th and 7th carbon atoms (counted from the methyl (CH3) terminal carbon atom and the omega-3 family of fatty acids have their first double bond between the 3rd and 4th carbon atom.
Both families of fatty acids are vital components of membranes and are used by the body in the production of eicosanoids, a vast range of highly bioactive substances (prostaglandins, leukotrienes, and lipoxins) but the activity of these metabolites varies. For example, the eicosanoids derived from omega-6 are in general more active (or reactive) than those produced from omega-3 and omega-6 is aggregatory whereas oega-6 is pro-aggregatory.
Basically, the omega-3s have anti-inflammatory benefits and help prevent heart disease, whereas omega-6s lower blood cholesterol and support the skin.
Like all fats, EFAs provide energy. Their calorific value is similar to other fats and oils but, unlike saturated fats, they have important health roles. In fact, as their name suggest, they are essential and must be consumed regularly as the body has limited storage for them.
Both of the important EFA families - omega-6 and omega-3 - are components of nerve cells and cellular membranes. They are converted by the body into eicosanoids, leukotrienes and prostaglandins - all of which are needed on a second-by-second basis by most tissue activities in the body.
EFAs are involved in normal physiology, including:
- Regulating pressure in the eye, joints, and blood vessels, and mediating immune response
- Regulating bodily secretions and their viscosity
- Dilating or constricting blood vessels
- Regulating collateral circulation
- Directing endocrine hormones to their target cells
- Regulating smooth muscles and autonomic reflexes
- Being primary constituents of cell membranes
- Regulating the rate of cell division
- Maintaining the fluidity and rigidity of cellular membranes
- Regulating the inflow and outflow of substances to and from cells
- Transporting oxygen from red blood cells to the tissues
- Maintaining proper kidney function and fluid balance
- Keeping saturated fats mobile in the blood stream
- Preventing blood cells from clumping together (blood clots that can be a cause of heart attack and stroke)
- Mediating the release of inflammatory substances from cells that may trigger allergic conditions
- Regulating nerve transmission and communication
- If the diet is deficient in either omega-6 or omega-3 long-term degenerative illnesses will result.
However, because the end product (eg prostaglandin, leukotriene) of EFA metabolism differ slightly but significantly from omega-6 to omega-3, they must be present in balance for optimum health.
Both omega-6 and omega-3 fatty acids are essential but the body requires them in a ratio that is not normally achieved by the typical diet of today's industrialized nations.
Experts think that man evolved on a diet which would have had roughly 1-2 times more omega-6 than omega-3, though there is a school of thought which argues for a 1:1 ratio. (Currently, average UK intakes are in a ratio of around 8:1 in favour of the omega-6s, while in the US it is around 10:1 and in Australia nearer 12:1. Many individuals within those populations will have an even greater omega-6 to omega-3 imbalance).
Sources of Omega 3 Fats:
Cold water fish, tuna, cod liver, halibut, herring, mackerel, trout, salmon, sardines.
Sources of Omega 6 fats:
Sunflower seeds, seed oils, corn, pumpkin seeds, sesame seeds, nuts, meat, dairy products.
This article was written by Doug Lawrenson. Doug is a diet and nutrition expert and has trained several male and female athletes to British National level. If you would like to chat to Doug you can catch him on our muscle building forum. It's free to register, so come and join our growing community of muscle builders and fitness enthusiasts!