The Perfect Omega 6 to 3 Ratio – Just a Myth?
Alpha-linolenic acid (ALA), an omega-3 fatty acid, and linoleic acid (LA), an omega-6 fatty acid, are polyunsaturated fatty acids (PUFAs) that are found in a wide range of foods. In the presence of certain enzymes, these fatty acids can be metabolized into long-chain PUFAs which play an important role in regulating inflammation. However, the conversion of ALA into its long-chain equivalents docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), and the conversion of LA into arachidonic acid (AA), is typically rather low.
AA tends to be pro-inflammatory, while long-chain PUFAs have been shown to exert anti-inflammatory effects and a high intake of the latter has been linked to a lower incidence of numerous diseases mediated by inflammatory mechanisms. As ALA and LA compete for the same enzymes for their conversion into the longer-chain fatty acids, it has been suggested that high intakes of omega-6 fatty acids might negate the anti-inflammatory effects of omega-3s. Some people even suggest that there is a specific ratio of omega-6 to omega-3 fatty acids you should aim at if your goal is to reduce chronic inflammation in your body.
However, the concept of an ideal omega-6 to omega-3 ratio is a controversial, and many authorities today believe that the concept of a perfect omega-6 to 3 ratio is nothing but a myth. These authorities typically suggest that your focus should be on correcting omega-3 deficiencies, rather than on balancing your omega 6 to 3 ratio. In this article, we will be looking at some of the arguments that have been put forward by experts who believe that having, or not having, a balanced omega 6 to 3 does not matter in the end.
The Problem with a Fixed Omega 6 to 3 Ratio
According to a paper summarizing the contents of a workshop at the UK Food Standards Agency, the idea of an optimal omega-6 to omega-3 fatty acid ratio has a number of problems. For example, the concept typically makes no distinction between the omega-3s ALA and EPA/DHA, nor does it distinguish between the omega-6s LA and AA. However, it is well established the different types of omega-3 fatty acids have very different effects, and the same applies for the different types of omega-6s.
A study published in the journal Circulation, for example, found inverse associations between EPA/DHA intake and plasma levels of certain inflammatory markers, but no association between ALA intake and inflammatory markers. What's more, these relations appeared to be dependent on the intake of n-6 fatty acids: when the omega-3 intake is low, omega-6 fatty acids appear to be associated with high levels of inflammatory markers; yet when the omega-3 intake is high, the combination of both types of fatty acids is related to the lowest levels of inflammation.
Another study, published in Annals of Nutrition and Metabolism and referenced in the UN's 2008 Expert Report on Fats and Fatty Acids in Human Nutrition, suggests that increasing LA intake does not result in increased levels of AA in plasma or platelet lipids, nor does it increase the formation of pro-inflammatory mediators.
The above study, together with the results of a 2000 study which found that both omega-6 and omega-3 fatty acids have anti-inflammatory properties protective of atherogenic changes in vascular endothelial cells, led the UN's Food and Agriculture Organization (FAO) to conclude that there is no rational for a specific recommendation for an omega-6 to omega-3 ratio, provided that the intakes of omega-6s and omega-3s lie within the recommendations established in their report (2.5 to 9% and 0.5 to 2 % of daily energy, respectively). This contradicts the conclusion of the UN's 2002 Expert Report on Diet, Nutrition and the Prevention of Chronic Diseases which suggested that a balanced intake of omega-6 and omega-3 fatty acids is essential for health.
The Bottom Line
Although the jury is still out on whether there is a specific ratio that could be considered the ideal, or 'perfect', omega-6 to omega-3 ratio, most experts seem to agree on one thing: Western diets are typically deficient in omega-3 fatty acids. To increase your intake of these health-promoting fatty acids, add foods like salmon, fish eggs, flaxseed, chia seeds and hemp seeds to your diet. Also fish oil and microalgae oil supplements are great sources of omega-3 fatty acids.
References:
1. J. Stanley et al (2007). UK Food Standards Agency Workshop Report: the effects of the dietary n-6:n-3 fatty acid ratio on cardiovascular health. British Journal of Nutrition, 98, 1305-1310.
2. T. Pischon et al (2003). Habitual Dietary Intake of n-3 and n-6 Fatty Acids in Relation to Inflammatory Markers Among US Men and Women. Circulation, 108:155-160.
3. O. Adam, G. Wolfram, G. et N. Zollner (2003). Influence of dietary linoleic acid intake with different fat intakes on arachidonic acid concentrations in plasma and platelet lipids and eicosanoid biosynthesis in female volunteers. Ann. Nutr. Metab, 47(1), 31-36.
4. FAO Food and Nutrition Paper. Fats and fatty acids in human nutrition Report of an expert consultation. Food and Agriculture Orhganizazion (FAO) of the United States, 2010.
5. De Caterina, R., Liao, J.K. & Libby, P. 2000. Fatty acid modulation of endothelial activation. Am. J. Clin. Nutr., 71(1 Suppl.), 213S-223S.
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