The Omega-6:Omega-3 Ratio Question
Posted by , MS, RD, CDE

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I was really surprised a few years ago when the American Heart Association (AHA) took the position that omega-6 fatty acids don’t increase inflammation.[i] For years, I had thought that omega-6s, particularly linoleic acid (LA), were pro-inflammatory. I remember from biochemistry that the omega-3 and omega-6 fatty acids compete for the same enzymes. Omega-3s are shuttled through a pathway that results in their conversion to anti-inflammatory compounds. Omega-6 fats, on the other hand, are converted to pro-inflammatory compounds. With heart disease and other chronic diseases related to the inflammatory state, it was logical that omega-6 polyunsaturated fats were bad and that omega-3 polyunsaturated fats were good. Thus, I taught my patients to simultaneously increase omega-3s and decrease omega-6s to shift the omega ratio away from inflammation.

However, since then, emerging research has proven that the omega-3 to omega-6 ratio theory is not evidence-based. Because I love learning new things about one of my favorite subjects — nutrition — I read as much as I could and talked to some experts. Today, I’m entirely onboard with ignoring the idea of the omega-3 to omega-6 “ratio.” This is some of what I learned:

  • The AHA concluded that consumption of at least five to 10 percent of calories from omega-6 fats reduces the risk of coronary heart disease (CHD) relative to lower intakes. Americans consume about 7 percent of total calories from omega-6 fats. Yes, increasing omega-3s reduces CHD risk, but it does not follow that reducing omega-6s does the same.i
  • Epidemiological studies do not support that a high omega-6 to omega-3 ratio is linked to excess inflammation. For example, one study found that the lowest levels of inflammation occurred in subjects with the highest consumption of all polyunsaturated fats, which includes omega-6s.[ii]
  • According to the report of the 2008 joint meeting of the Food and Agricultural Organization of the United Nations and the World Health Organization, there is no rationale for a specific ratio of omega-6 to omega-3 fatty acids and that an appropriate intake of omega-6 fats is 2.5 — 9 percent of calories.[iii]
  • In a 2012 review paper in the Journal of the Academy of Nutrition and Dietetics, the authors state that there are virtually no data from randomized, controlled intervention studies among healthy non-infants to show that adding LA to diets increases markers of inflammation. Furthermore, they state that the dietetic community should be reassured to counsel clients and patients using current recommendations that emphasize eating habits which include both omega-3 and omega-6 fats.ii

I am reassured. Today, I teach my patients to enjoy a variety and balance of polyunsaturated and monounsaturated fats. They’re all good fats.

[i] Harris WS, Mozaffarian D, et al. Omega-6 Fatty Acids and Risk for Cardiovascular Disease: A Science Advisory From the American Heart Association Nutrition Subcommittee of the Council on Nutrition, Physical Activity, and Metabolism; Council on Cardiovascular Nursing; and Council on Epidemiology and Prevention. Circulation. 2009;119:902-907.
[ii] Johnson GH and Fritsche K. Effect of Dietary Linoleic Acid on Markers of Inflammation in Healthy Persons: A Systematic Review of Randomized Controlled Trials. J Acad Nutr Diet. 2012;112:1029-1041.
[iii] Food and Agricultural Organization of the United Nations. Fats and Fatty Acids in Human Nutrition: Report of an expert consultation. FAO Food and Nutrition Paper 91. 2010.