Omega-6 is the name given to a group of fats that are essential for the health of our brain and heart. Our bodies can’t make omega-6, so we have to consume them as part of our diet.
Most of the omega-6 in our diets comes in the form of linoleic acid (LA), found in vegetables and seed oils like sunflower, soya bean, sesame and corn oil. Another omega-6, called arachidonic acid (AA) is found in meat, dairy and eggs.
Just like omega-3, omega-6 fats give structure to our cell membranes and are used to make locally acting hormones that play a role in regulating inflammation and immune function. Omega-6 fats are thought to produce more pro-inflammatory hormones than omega-3 fats1,2, and for this reason, it’s thought that diets high in omega-6 can increase inflammation in the body3,4,5.
What do we know about omega-6 and psoriasis?
Studies show people with psoriasis tend to have lower levels of essential fatty acids in their skin and tissues compared to healthy controls1 and higher concentrations of omega-6, an imbalance which may contribute to the elevated levels of inflammation seen in psoriasis 7.
Changing the ratio of omega-3 to omega-6 in the body via diet or supplements may help psoriasis by reducing inflammation, as the two omega families compete for the same metabolic pathway, so by increasing one, it’s possible to suppress the other 14.
For example, omega-3 can reduce the amount of omega-6 in cell membranes 4, which may slow the production of inflammatory hormones.
What does the science say?
No studies have looked at the effects of reducing omega-6 through dietary changes alone. Instead, the majority have assessed the impact of suppressing omega-6 with omega-3 supplementation, with studies showing that daily doses of between 2 and 12 grams of omega-3 can positively impact psoriasis severity 15,16.
If we look at studies that have reduced omega-6 as part of an overall treatment plan, there’s evidence of some positive results. In one 1983 study of 20 patients with arthritis and skin diseases (including psoriasis) a vegetarian diet low in omega-6 was shown to maintain the improvement in symptoms achieved after an initial two-week fast 17.
More recently, in a 2013 study of overweight patients with mild to severe plaque psoriasis, a reduced calorie diet enriched with omega-3 and low in omega-6 significantly improved psoriasis severity, itching and quality of life score18. However, it’s not possible to say whether this was due to the weight loss, increased omega-3, reduced omega-6 or a combination of all factors.
Outside of psoriasis, a diet low in omega-6 was shown to reduce inflammation in patients with rheumatoid arthritis 19. In this study, patients placed on an anti-inflammatory diet consumed less than 90 milligrams of arachidonic acid per day, with meat limited to twice a week. When fish oil was added during the final 2 months of the 8-month study, even greater improvements in joint pain and swelling were seen.
How much omega-6 is too much?
It’s difficult to say how much omega-6 we should be consuming, as the ideal ‘ratio’ isn’t clear. However, changes to Western diets show that we’re now consuming more omega-6 and less omega-3 than our ancestors 35.
For example, we’re eating more vegetable oils and meat and less oily fish, which mean the ratio of omega-6 to omega-3 in our diet has increased from 2:1 to more than 10:15.
Although the ideal isn’t clear, evidence suggests changing the balance in favour of omega-3 through supplements or changes to diet may be helpful in psoriasis.
- Omega-6 are a family of essential fats found in vegetable and seed oils, meat, and eggs. They are important for health, but it large amounts may have pro-inflammatory effects
- Studies show patients with psoriasis have raised levels of the omega-6 which may aggravate the inflammatory response
- Studies are limited, but changing the ratio of omega-3 to omega-6 in the diet through omega-3 supplementation or reduced intake of omega-6 appears helpful in reducing psoriasis severity
- Wolters M. Diet and psoriasis: experimental data and clinical evidence. Br. J. Dermatol. 2005;153(4):706-714. doi:10.1111/j.1365-2133.2005.06781.x.
- Wall R, Ross RP, Fitzgerald GF, Stanton C. Fatty acids from fish: The anti-inflammatory potential of long-chain omega-3 fatty acids. Nutr. Rev. 2010;68(5):280-289. doi:10.1111/j.1753-4887.2010.00287.x.
- Weaver KL, Ivester P, Seeds M, Case LD, Arm JP, Chilton FH. Effect of dietary fatty acids on inflammatory gene expression in healthy humans. J. Biol. Chem. 2009;284(23):15400-15407. doi:10.1074/jbc.M109.004861.
- Patterson E, Wall R, Fitzgerald GF, Ross RP, Stanton C. Health implications of high dietary omega-6 polyunsaturated Fatty acids. J. Nutr. Metab. 2012;2012:539426. doi:10.1155/2012/539426.
- Simopoulos a. P. The importance of the ratio of omega-6/omega-3 essential fatty acids. Biomed. Pharmacother. 2002;56(8):365-379. doi:10.1016/S0753-3322(02)00253-6.
- Vessby CVBBM. The fatty-acid spectrum in plasma and adipose tissue in patients with psoriasis. Arch. Dermatol. Res. 1985;278(2):114-119. doi:http://dx.doi.org/10.1007/BF00409217.
- Azzini M, Girelli D, Olivieri O, et al. Fatty acids and antioxidant micronutrients in psoriatic arthritis. J. Rheumatol. 1995;22(1):103-8. Available at: http://www.ncbi.nlm.nih.gov/pubmed/7699656.
- Sadik CD, Sezin T, Kim ND. Leukotrienes orchestrating allergic skin inflammation. Exp. Dermatol. 2013;22(11):705-9. doi:10.1111/exd.12239.
- Hendriks a GM, Keijsers RRMC, Seyger MMB, van de Kerkhof PCM, van Erp PEJ. Cutaneous application of leukotriene B4 as an in vivo model of psoriasis-like skin inflammation: an immunohistological study. Skin Pharmacol. Physiol. 2014;27(3):120-6. doi:10.1159/000354119.
- Ruzicka T, Simmet T, Peskar BA, Ring J. Skin levels of arachidonic acid-derived inflammatory mediators and histamine in atopic dermatitis and psoriasis. J. Invest. Dermatol. 1986;86(2):105-108. doi:10.1111/1523-1747.ep12284061.
- P. M, H. G, F. G. n-3 fatty acids in psoriasis. Br. J. Nutr. 2002;87(SUPPL. 1):S77-S82. Available at: http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=reference&D=emed5&NEWS=N&AN=2002059514.
- Brain S, Camp R, Dowd P, Black a K, Greaves M. The release of leukotriene B4-like material in biologically active amounts from the lesional skin of patients with psoriasis. J. Invest. Dermatol. 1984;83(1):70-73. doi:10.1111/1523-1747.ep12261712.
- Maurice PD, Camp RD, Allen BR. The metabolism of leukotriene B4 by peripheral blood polymorphonuclear leukocytes in psoriasis. Prostaglandins 1987;33(6):807-818. Available at: http://www.ncbi.nlm.nih.gov/pubmed/2823314.
- James MJ, Gibson R a, Cleland LG. Dietary polyunsaturated fatty acids and inflammatory mediator production. Am. J. Clin. Nutr. 2000;71(1 Suppl):343S-8S.
- Habermann NT, De C. Efficacy of omega-3 fatty acids in the treatment of psoriasis. Rev. Bras. Med. 1994;51:779-783. Available at: http://onlinelibrary.wiley.com/o/cochrane/clcentral/articles/687/CN-00170687/frame.html.
- P. M, F. G, C. P, E. S, W. S. Reproducible effects of intravenously administered fish-oil in acute relapsing psoriasis. J. Dermatolog. Treat. 1996;7(4):211-214. Available at: http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=reference&D=emed4&NEWS=N&AN=1997028592.
- Lithell H, Bruce A, Gustafsson IB, et al. A fasting and vegetarian diet treatment trial on chronic inflammatory disorders. Acta Derm. Venereol. 1983;63(5):397-403.
- Guida B, Napoleone A, Trio R, et al. Energy-restricted, n-3 polyunsaturated fatty acids-rich diet improves the clinical response to immuno-modulating drugs in obese patients with plaque-type psoriasis: a randomized control clinical trial. Clin. Nutr. 2013;33(3):399-405. doi:10.1016/j.clnu.2013.09.010.
- Adam O, Beringer C, Kless T, et al. Anti-inflammatory effects of a low arachidonic acid diet and fish oil in patients with rheumatoid arthritis. Rheumatol. Int. 2003;23(1):27-36. doi:10.1007/s00296-002-0234-7.
- Kapoor R, Huang Y-S. Gamma linolenic acid: an antiinflammatory omega-6 fatty acid. Curr. Pharm. Biotechnol. 2006;7(6):531-534. doi:10.2174/138920106779116874.
- Kragballe K. Dietary supplementation with a combination of n-3 and n-6 fatty acids (super gamma-oil marine) improves psoriasis. Acta Derm. Venereol. 1989;69(3):265-268.
- Soyland E, Funk J, Rajka G, et al. Effect of dietary supplementation with very-long-chain n-3 fatty acids in patients with psoriasis. N. Engl. J. Med. 1993;328(25):1812-1816. doi:10.1056/NEJM199306243282504.
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