It is generally known that in order to maintain good health we have two essential fatty acids that we must consume. Commonly, these are known as omega-3 and omega-6 fatty acids. Research is uncovering both the anti- and pro-inflammatory roles they play, and are helping us to understand the intricacies of their influence on inflammatory diseases.
Both polyunsaturated fatty acids (PUFAs) ; omega-6 and omega-3 are considered ‘essential‘ because the body is unable to synthesise them itself, so they must be acquired through diet. Some PUFAs are considered to be ‘conditionally essential’ as there is the potential for the body to synthesise the fatty acid by converting a precursor PUFA molecule. However, this is dependent on many factors, such as the intake of other fatty acids.Burdge GC, Finnegan YE, Minihane AM, Williams CM, Wootton SA. Effect of altered dietary n-3 fatty acid intake upon plasma lipid fatty acid composition, conversion of [C]α-linolenic acid to longer-chain fatty acids and partitioning towards β-oxidation in older men. Br J Nutr. 2003;90(02):311. As both omega-3 and 6 conversion pathways utilise the same enzymes, this creates competition, which may lead to the favour of a certain type of fatty acid over another.Trebatická J, Dukát A, Ďuračková Z, Muchová J. Cardiovascular diseases, depression disorders and potential effects of omega-3 fatty acids. Physiol Res. 2017 Jul 18;66(3):363–82. This is an issue when a person’s diet is lacking in these essential nutrients, as they play many important roles and can be a huge influence on inflammation in the body.
In order for the insurance that we are meeting our omega needs, it is recommended that we consume both those that are essential and conditionally essential at a level to ensure adequate intake. This includes both the essential linoleic (omega-6) and alpha-linolenic (omega-3) fatty acids, as well as a suggestion for the total amount of the conditionally essential, DHA, DPA and EPA omega-3 fatty acids. This is because we tend to consume more omega-6 than we do omega-3. When this ratio is unbalanced and heavily swayed to the omega-6 end we are more likely to be converting the omega-6 fatty acids and not the omega-3’s. This can result in deficiency of these conditionally essential fatty acids, and is why our diets should also contain these nutrients. In the past, the omega ratio was likely to have been 4:1 of omega-6 to omega-3 fatty acids. In the western diet, this ratio has become very unbalanced, closing in on 16:1.Simopoulos AP. An Increase in the Omega-6/Omega-3 Fatty Acid Ratio Increases the Risk for Obesity. Nutrients. 2016 Mar 2;8(3):128. Large amounts of omega-6 fatty acids are consumed in the the form of vegetable and seed oils. Seafood, flaxseeds and walnuts provide omega-3 fatty acids.Simopoulos AP. An Increase in the Omega-6/Omega-3 Fatty Acid Ratio Increases the Risk for Obesity. Nutrients. 2016 Mar 2;8(3):128. In a modern western diet there are high quantities of food fried in vegetable oil and less fresh seafood. In comparison to traditional Mediterranean or Japanese diets where seafood is abundant and fried food is consumed sparingly, the ratio of omega-6 to omega-3 is in greater balance.Simopoulos AP. Evolutionary aspects of omega-3 fatty acids in the food supply. Prostaglandins Leukot Essent Fatty Acids. 1999 May;60(5-6):421–9.
Omega-3 and anti-inflammatory are fairly synonymous. Both omega-3 and omega-6 are involved in the processes of inflammation in the body, although with differing effects. It is not as simple as distinguishing them by their anti-inflammatory potential. Their action is far more complicated.
One important role of polyunsaturated fats is their use by cells for the production of signalling molecules that function as regulators of inflammation, called eicosanoids. For omega-3, both EPA and DHA can be channeled down pathways that result in specific eicosanoids that can resolve inflammation (resolvins) and ensure proper regulation (protectins) which form the basis of the anti-inflammatory effects that are seen.Trebatická J, Dukát A, Ďuračková Z, Muchová J. Cardiovascular diseases, depression disorders and potential effects of omega-3 fatty acids. Physiol Res. 2017 Jul 18;66(3):363–82. Although, prostaglandins and leukotrienes produced from omega-3 fatty acids also stimulate a low level of inflammation. In contrast, eicosanoids produced from omega-6 fatty acids, arachidonic acid (AA) give rise to prostaglandins and leukotrienes that have a higher inflammatory potential.Simopoulos AP. An Increase in the Omega-6/Omega-3 Fatty Acid Ratio Increases the Risk for Obesity. Nutrients. 2016 Mar 2;8(3):128. This is where the contrast between the two essential fatty acids are clear. However, the omega-6 fatty acid AA can also be channeled to become an eicosanoid lipoxin which is anti-inflammatory and a resolver of inflammation.Gobbetti T, Ducheix S, le Faouder P, Perez T, Riols F, Boue J, et al. Protective effects of n-6 fatty acids-enriched diet on intestinal ischaemia/reperfusion injury involve lipoxin A4 and its receptor. Br J Pharmacol. 2015 Feb;172(3):910–23. This demonstrates that it is not only the omega-3 fatty acids which play an anti-inflammatory role.
As discussed, it is an issue when too little omega-3, and too much omega-6 is consumed. Now we can see this imbalance will translate directly to either driving inflammation, or resolving it. While both omega-6 and omega-3 fatty acids are an essential and integral part of our diets, it is important that they are consumed in balance in accordance with dietary guidelines. Omega-3 intake is associated with a reduced risk of cardiovascular diseases, obesity, diabetes.Simopoulos AP. The importance of the omega-6/omega-3 fatty acid ratio in cardiovascular disease and other chronic diseases. Exp Biol Med . 2008 Jun;233(6):674–88. While it is more complex than its anti-inflammatory action; an imbalance is a highly substantiated contributing factor for the genesis of these diseases.
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