Omega-3 vs. Omega-6: Rethinking the Hypothesis

When you’re eating a meal, you’re probably not thinking about macronutrients, like carbohydrates, fats and proteins. The vast majority of individuals following a Western diet aren’t consciously thinking is this food essential to the human body? It is important to note, however, that while there is no such thing as an “essential carbohydrate,”¹ there are “essential fats.”² Essential in the sense that the human body cannot make these fats endogenously,³ and therefore, must be obtained via diet or supplementation.⁴ Within the class of essential fats, we have omega-3, which has different forms such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (E'PA).⁵ However, omega-3 is more commonly known to the general populace as "fish oil.”

Omega 3 fatty acids are long chain in structure and found in a variety of foods.⁶ The action of these long chain fatty acids is commonly called "anti-inflammatory," though this is a misnomer.⁷ They are simply less inflammatory than omega-6 fatty acids. Omega-3 FAs and omega-6 FAs compete for the same enzyme to eventually be converted into anti-inflammatory prostaglandins (PGE3) and less inflammatory leukotrienes and into pro-inflammatory prostaglandins (PGE2) and more inflammatory leukotrienes, respectively.⁸ This paper then goes on to declare, it is the ratio of omega-6 to omega-3 that is vital to reduce or promote the overall inflammatory state of the body.^9,10,11 When we look to the habits of hunter-gatherers, the ratio of omega-6 to omega-3 has been estimated at 2:1 or 3:1.¹² This is in contrast to the modern diet, which has been estimated at 10:1, or even 25:1.¹³

With this evidence, it is assumed that emulating the ratio of hunter-gatherers is correct, if we want to improve bio-markers of health.¹⁴ Certainly the theory that an inflammatory diet, full of omega-6 rich vegetable oils and very little omega-3 would likely lead to health problems, makes basic sense.¹⁵ However, newer research suggests both omega-6 and omega-3 FAs reduce the risk of heart disease, and the ratio of these fatty acids is “not useful and can be misleading.”¹⁶ One study reported that omega-6 FAs do not inhibit the beneficial effects of omega-3 FAs, and the combination of both fatty acids leads to the greatest reduction in levels of inflammation.¹⁷

However, the real issue here is that omega-3 FAs bind to G coupled-protein receptors, and cause broad anti-inflammatory effects.¹⁸ If you remove the omega-3 FAs from your diet, inflammation returns. This means that adequate omega-3 intake alone, regardless of omega-6 intake, is enough to stop inflammation in the body. The same is apparent when you look at the biochemical pathway of omega-6 and omega-3 FAs. They compete for the same enzyme¹⁹ through a process known as competitive inhibition.²⁰

The best method of action to pursue, is to simply follow a Paleo Diet and eat plenty of fish rich in omega-3. If you want to avoid dietary intake of omega-3, and obtain the requirements solely from a supplement, DHA is preferable to all other forms of omega-3, since it can be retro converted into EPA.²¹ Only in the context of a very inflammatory diet (like the standard Western diet) does the ratio of omega-3 to 6 matter. Another case where the ratio would be of utmost importance, is if you aren’t getting any omega-3 FAs at all. This isn’t to say that the omega-3 to omega-6 ratio is completely irrelevant, but if you’re consuming a Paleo Diet, you will likely be getting the right amounts of these essential fatty acids for optimal health.

References

1. Westman EC. Is dietary carbohydrate essential for human nutrition?. Am J Clin Nutr. 2002;75(5):951-3.

2. Insel, Paul. Nutrition: Custom Edition. 4th Edition. Jones & Bartlett Learning, 2010; 182.

3. Chang CY, Ke DS, Chen JY. Essential fatty acids and human brain. Acta Neurol Taiwan. 2009;18(4):231-41.

4. Singh M. Essential fatty acids, DHA and human brain. Indian J Pediatr. 2005;72(3):239-42.

5. Wainwright PE. Dietary essential fatty acids and brain function: a developmental perspective on mechanisms. Proc Nutr Soc. 2002;61(1):61-9.

6. Meyer BJ, Mann NJ, Lewis JL, Milligan GC, Sinclair AJ, Howe PR. Dietary intakes and food sources of omega-6 and omega-3 polyunsaturated fatty acids. Lipids. 2003;38(4):391-8.

7. Foitzik T, Eibl G, Schneider P, Wenger FA, Jacobi CA, Buhr HJ. Omega-3 fatty acid supplementation increases anti-inflammatory cytokines and attenuates systemic disease sequelae in experimental pancreatitis. JPEN J Parenter Enteral Nutr. 2002;26(6):351-6.

8. Macsai MS. The role of omega-3 dietary supplementation in blepharitis and meibomian gland dysfunction (an AOS thesis). Trans Am Ophthalmol Soc. 2008;106:336-56.

9. Simopoulos AP. The importance of the ratio of omega-6/omega-3 essential fatty acids. Biomed Pharmacother. 2002;56(8):365-79.

10. Gómez candela C, Bermejo lópez LM, Loria kohen V. Importance of a balanced omega 6/omega 3 ratio for the maintenance of health: nutritional recommendations. Nutr Hosp. 2011;26(2):323-9.

11. 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.

12. 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(2):341-54.

13. Yan L, Bai XL, Fang ZF, Che LQ, Xu SY, Wu D. Effect of different dietary omega-3/omega-6 fatty acid ratios on reproduction in male rats. Lipids Health Dis. 2013;12:33.

14. Apte SA, Cavazos DA, Whelan KA, Degraffenried LA. A low dietary ratio of omega-6 to omega-3 Fatty acids may delay progression of prostate cancer. Nutr Cancer. 2013;65(4):556-62.

15. Kang JX, Liu A. The role of the tissue omega-6/omega-3 fatty acid ratio in regulating tumor angiogenesis. Cancer Metastasis Rev. 2013;32(1-2):201-10.

16. Anton SD, Heekin K, Simkins C, Acosta A. Differential effects of adulterated versus unadulterated forms of linoleic acid on cardiovascular health. J Integr Med. 2013;11(1):2-10.

17. Pischon T, Hankinson SE, Hotamisligil GS, Rifai N, Willett WC, Rimm EB. Habitual dietary intake of n-3 and n-6 fatty acids in relation to inflammatory markers among US men and women. Circulation. 2003; 108(2): 155-160.

18. Oh DY, Talukdar S, Bae EJ, et al. GPR120 is an omega-3 fatty acid receptor mediating potent anti-inflammatory and insulin-sensitizing effects. Cell. 2010;142(5):687-98.

19. Babcock TA, Novak T, Ong E, Jho DH, Helton WS, Espat NJ. Modulation of lipopolysaccharide-stimulated macrophage tumor necrosis factor-alpha production by omega-3 fatty acid is associated with differential cyclooxygenase-2 protein expression and is independent of interleukin-10. J Surg Res. 2002;107(1):135-9.

20. Oleñik A, Mahillo-fernández I, Alejandre-alba N, et al. Benefits of omega-3 fatty acid dietary supplementation on health-related quality of life in patients with meibomian gland dysfunction. Clin Ophthalmol. 2014;8:831-6.

21. Conquer JA, Holub BJ. Dietary docosahexaenoic acid as a source of eicosapentaenoic acid in vegetarians and omnivores. Lipids. 1997;32(3):341-5.

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