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
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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.
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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.
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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.
