The plethora of scientific studies on lipids and nutrition would have nutritionists thinking within reason that omega-3s are the chosen fatty acid to deliver humankind from sickness. But despite the seemingly omnipotent oil’s overabundance of qualities, not nearly enough is known about how much to consume in relation to other fatty acids such as omega-6.
In June 2008, top cardiologists convened to examine all clinical evidence and discuss optimal omega-3 dosages (1). The conclusions were summarized with a recommendation of at least 250 mg of DHA and EPA fatty acids for the “primary prevention of cardiovascular disease” (1). No ratio recommendation was given, which was purposeful.
In fact, the focus on omega-3 to omega-6 ratios had been heavily criticized earlier. A report in 2007 by the UK Food Standards Agency said that “ratio is not a useful concept and it distracts attention away from absolute intakes” (2). And a year earlier, top American omega-3 fatty acid researcher William S. Harris, Ph.D., of University of South Dakota’s Nutrition and Metabolic Diseases Research Institute wrote that “although initially appealing” for making nutritional recommendations, ratio is “of little value” (3). Lacking clinical data, the UK Food Standards Agency, Dr Harris and others may be correct in calling for concentration solely on omega-3 for established treatment(4;5).
Many clinicians and researchers, however, continue to advise and perform studies from the theoretical viewpoint of a ratio. A microscopic view reveals answers to why. The function of omega-3 and omega-6 in the cell or an organ such as the liver or brain highlights key differences. Dr Harris does concede these facts: that the two fatty acids compete for enzymes and have opposite effects (3). In addition to omega-3’s anti-inflammatory and omega-6’s inflammatory uniqueness (6), the biochemistry also presents information on how each influences metabolism, genetic expression (6-10), cell membrane function and neurotransmission (6;11). While insightful, however, the information does stop short of any clinical parameters.
As a base for perspective, nutritionists find it useful to turn to dietary origins. Nutritional anthropology and epidemiological studies suggest a ratio of 1-2:1 omega-6 to omega-3, which is in large contrast to the typical Western diet of 15-16:1 (6;12-15). And many ratios resembling the ideal hunter-gatherer 1:1 do propose significant reduction of risk of chronic disease, mainly coronary artery disease and arthritis (6;15). These research approaches come with caution as they are not enough for science in absolute, nor do they offer indication of any exact amounts for best efficacy.
Truer data must come from well-designed randomized, double-blind controlled trials. To reflect proper indications, these studies should take into account ratio, amounts or both. An example of a trial was conducted in 2003 when two parallel groups of 15 patients who each had major elective abdominal surgery were given omega-6 to omega-3 ratio of 3:1, which confirmed a significant anti-inflammatory effect (16). More trials such as this one could illuminate further.
Reference List
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2. Stanley JC, Elsom RL, Calder PC et al. UK Food Standards Agency Workshop Report: the effects of the dietary n-6:n-3 fatty acid ratio on cardiovascular health. Br J Nutr 2007;98:1305-10.
3. Harris WS. The omega-6/omega-3 ratio and cardiovascular disease risk: uses and abuses. Curr Atheroscler Rep 2006;8:453-9.
4. Harris WS. Omega-3 fatty acids and cardiovascular disease: a case for omega-3 index as a new risk factor. Pharmacol Res 2007;55:217-23.
5. Harris WS, Assaad B, Poston WC. Tissue omega-6/omega-3 fatty acid ratio and risk for coronary artery disease. Am J Cardiol 2006;98:19i-26i.
6. Simopoulos AP. The omega-6/omega-3 fatty acid ratio, genetic variation, and cardiovascular disease. Asia Pac J Clin Nutr 2008;17 Suppl 1:131-4.
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9. Lu Y, Nie D, Witt WT et al. Expression of the fat-1 gene diminishes prostate cancer growth in vivo through enhancing apoptosis and inhibiting GSK-3 beta phosphorylation. Mol Cancer Ther 2008;7:3203-11.
10. El-Badry AM, Graf R, Clavien PA. Omega 3 - Omega 6: What is right for the liver? J Hepatol 2007;47:718-25.
11. Haag M. Essential fatty acids and the brain. Can J Psychiatry 2003;48:195-203.
12. Simopoulos AP. Evolutionary aspects of diet, the omega-6/omega-3 ratio and genetic variation: nutritional implications for chronic diseases. Biomed Pharmacother 2006;60:502-7.
13. Cordain L, Eaton SB, Sebastian A et al. Origins and evolution of the Western diet: health implications for the 21st century. Am J Clin Nutr 2005;81:341-54.
14. Simopoulos AP. The importance of the omega-6/omega-3 fatty acid ratio in cardiovascular disease and other chronic diseases. Exp Biol Med (Maywood ) 2008;233:674-88.
15. Simopoulos AP. The importance of the ratio of omega-6/omega-3 essential fatty acids. Biomed Pharmacother 2002;56:365-79.
16. Koller M, Senkal M, Kemen M, Konig W, Zumtobel V, Muhr G. Impact of omega-3 fatty acid enriched TPN on leukotriene synthesis by leukocytes after major surgery. Clin Nutr 2003;22:59-64.
