The dietary balance of polyunsaturated fatty acids (PUFAs), particularly omega-3 and omega-6 fatty acids, has been a topic of ongoing discussion. These essential fatty acids play critical roles in cell membrane structure, eicosanoid synthesis and regulation of inflammatory pathways. However, the narrative that omega-6 fatty acids are uniformly pro-inflammatory while omega-3 fatty acids are anti-inflammatory has often been oversimplified in academic and public discourse.
Omega 3
Omega-3 fatty acids are a group of essential polyunsaturated fats, meaning they must be obtained from the diet. The most biologically important omega-3s include:
- EPA (eicosapentaenoic acid)
- DHA (docosahexaenoic acid)
- ALA (alpha-linolenic acid)
ALA is converted in small amounts to EPA and DHA, which are the active forms associated with most health benefits.
The benefits
Omega-3 fatty acids possess well-documented anti-inflammatory properties that benefit a range of physiological functions. They are known to reduce systemic inflammation and decrease biomarkers such as C-reactive protein (CRP) and interleukin-6 (IL-6). Meta-analyses indicate that omega-3 fatty acids, particularly EPA and DHA, are associated with a reduced risk of chronic inflammatory conditions, including cardiovascular disease.1 Additionally, omega-3s support cardiovascular health by lowering triglyceride levels, improving the lipid profile and enhancing endothelial function. 2,3 These fatty acids also play a role in improving metabolic health by supporting insulin sensitivity, reducing obesity-related inflammation and promoting liver health.4
Dietary sources
Rich sources of EPA and DHA include cold-water fatty fish such as salmon, mackerel, sardines, anchovies and herring. Algal oil for vegetarians and vegans is also an effective source. ALA is primarily found in plant-based foods such as flaxseeds, chia seeds, walnuts and canola oil. However, clinical efficacy is strongly linked to EPA and DHA due to their direct bioactivity.
Omega 6
Omega-6 fatty acids are another class of essential polyunsaturated fats. The primary dietary omega-6 is linoleic acid (LA), which can be converted to gamma-linolenic acid (GLA) or arachidonic acid (AA). AA is a precursor for eicosanoid molecules that can have pro- or anti-inflammatory effects, depending on the context.
The benefits
Despite often being labelled as pro-inflammatory, omega-6 fatty acids have several important roles in human health. They support immune function and wound healing by modulating cell migration and proliferation, phagocytic capacity and production of inflammatory mediators during tissue repair.5 They contribute to brain development and reproductive health, and are critical for foetal neurodevelopment and neuronal membrane formation.6 They help maintain healthy skin and hair through effects of linoleic acid on skin barrier integrity and lipid composition.5 They also play roles in gene regulation and cell signalling, through eicosanoid production and modulation of cytokine and interleukin activity. The derivative gamma-linoleic acid (GLA), produced from linoleic acid, may exhibit anti-inflammatory effects in conditions including rheumatoid arthritis and eczema. Clinical trials have demonstrated GLA supplementation reduces disease activity and pain in rheumatoid arthritis and in vitro studies show GLA attenuates pro-inflammatory cytokine production by immune cells.7,8
Sources
Sources of omega-6 fatty acids include a variety of plant and animal-based foods. Common dietary sources are vegetable oils such as soybean, corn, safflower and sunflower oil. Nuts and seeds also provide significant amounts of omega-6, along with eggs, poultry and meat. Additionally, evening primrose oil and borage oil are notable for their GLA content.
Why the ratio matters
Concern regarding omega-6 fatty acids is not due to their presence in the diet, rather their dominance. The optimal omega-6 to omega-3 ratio is estimated to have been approximately 1:1 to 4:1 throughout human evolution, supporting balanced inflammatory responses and optimal cellular function.9 However, modern Western diets often reach ratios as high as 15:1 or even 20:1, heavily skewed toward omega-6 intake.10 This imbalance can promote a pro-inflammatory environment, particularly when omega-3 intake is low.11 Both omega-6 and omega-3 fatty acids share the same enzymatic pathways for conversion into their long-chain active forms.12 This means that excessive omega-6 intake can competitively inhibit omega-3 metabolism, leading to reduced production of anti-inflammatory mediators like EPA and DHA and increased production of pro-inflammatory eicosanoids derived from arachidonic acid.13 Over time, this imbalance may contribute to the pathogenesis of chronic diseases including cardiovascular disease, autoimmune disorders and inflammatory conditions.9,11
Seed oils
Despite widespread claims on social media, current scientific evidence does not support the idea that seed oils are inherently harmful to human health. Seed oils such as canola, soybean and sunflower oil are extracted from seeds and are rich in essential nutrients like vitamin E, phytosterols and PUFAs, particularly LA. Critics often argue that increased seed oil consumption contributes to chronic diseases and introduces oxidised or refined compounds into the diet. However, these claims are largely unfounded. While LA intake has increased in Western diets, systematic reviews show that it does not increase tissue arachidonic acid levels, a key inflammatory mediator, as previously feared.14 Increasing LA intake in healthy individuals has not been shown to raise systemic inflammation markers such as C-reactive protein or IL-6.15 Furthermore, higher LA intake is consistently associated with reduced risk of cardiovascular disease and improved cardiometabolic health.16 While some seed oils are refined for stability and shelf life, this does not inherently make them harmful. In fact, oils high in monounsaturated fats, like canola oil, tend to be more stable at high heat and have higher smoke points, making them suitable for cooking. Thus, demonising seed oils oversimplifies complex nutritional science and often distracts from the real dietary concern, excessive consumption of ultra-processed foods, not seed oils themselves.17
Conclusion
It is a common misconception that omega-6 fatty acids are uniformly pro-inflammatory. In reality, linoleic acid, the primary dietary omega-6, does not directly promote inflammation in healthy individuals when consumed in appropriate amounts. Furthermore, omega-6 can exert both pro- and anti-inflammatory effects depending on the physiological context. Omega-6 fats are essential nutrients that the body cannot synthesise on its own, playing critical roles in maintaining overall health. The real issue lies not in the presence of omega-6 fatty acids themselves, but in their excessive intake relative to omega-3s, which creates an imbalance that can shift the body toward a more inflammatory state. Rather than vilifying omega-6s, the focus should shift to achieving a healthier balance between omega-6 and omega-3 fatty acids. Both are essential and support vital biological functions. A balanced diet emphasising whole foods, healthy fat sources and diversity of omega-3 and omega-6 fatty acid sources can promote optimal health and support the body’s ability to regulate inflammation effectively.
References
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2. Tortosa-Caparrós, E., Navas-Carrillo, D., Marín, F., & Orenes-Piñero, E. (2016). Anti-inflammatory effects of omega 3 and omega 6 polyunsaturated fatty acids in cardiovascular disease and metabolic syndrome. Critical Reviews in Food Science and Nutrition, 57(16), 3421–3429. https://doi.org/10.1080/10408398.2015.1126549
3. Djuricic, I., & Calder, P. C. (2021). Beneficial outcomes of omega-6 and omega-3 polyunsaturated fatty acids on human health: An update for 2021. Nutrients, 13(7), 2421. https://doi.org/10.3390/nu13072421
4. Belury, M. A. (2023). Linoleic acid, an omega-6 fatty acid that reduces risk for cardiometabolic diseases: premise, promise and practical implications. Current Opinion in Clinical Nutrition and Metabolic Care, 26(3), 288–292. https://doi.org/10.1097/MCO.0000000000000919
5. Silva, J. R., Burger, B., Kühl, C. M. C., Candreva, T., dos Anjos, M. B. P., & Rodrigues, H. G. (2018). Wound healing and omega-6 fatty acids: From inflammation to repair. Mediators of Inflammation, 2018, 1–17. https://doi.org/10.1155/2018/2503950
6. Shahabi, B., Hernández-Martínez, C., Jardí, C., Aparicio, E., & Arija, V. (2025). Maternal omega-6/omega-3 concentration ratio during pregnancy and infant neurodevelopment: The ECLIPSES Study. Nutrients, 17(1), 170–170. https://doi.org/10.3390/nu17010170
7. Zurier, R. B., Rossetti, R. G., Jacobson, E. W., Demarco, D. M., Liu, N. Y., Temming, J. E., White, B. M., & Laposata, M. (1996). Gamma-linolenic acid treatment of rheumatoid arthritis. A randomized, placebo-controlled trial. Arthritis & Rheumatism, 39(11), 1808–1817. https://doi.org/10.1002/art.1780391106
8. Furse, R. K., Rossetti, R. G., & Zurier, R. B. (2001). Gammalinolenic acid, an unsaturated fatty acid with anti-inflammatory properties, blocks amplification of IL-1β production by human monocytes. The Journal of Immunology, 167(1), 490–496. https://doi.org/10.4049/jimmunol.167.1.490
9. Simopoulos, A. P. (2008). The importance of the omega-6/omega-3 fatty acid ratio in cardiovascular disease and other chronic diseases. Experimental Biology and Medicine (Maywood, N.J.), 233(6), 674–688. https://doi.org/10.3181/0711-MR-311
10. Simopoulos, A. P. (2006). Evolutionary aspects of diet, the omega-6/omega-3 ratio and genetic variation: nutritional implications for chronic diseases. Biomedicine & Pharmacotherapy, 60(9), 502–507. https://doi.org/10.1016/j.biopha.2006.07.080
11. DiNicolantonio, J. J., & O’Keefe, J. (2021). The importance of maintaining a low omega-6/omega-3 ratio for reducing the risk of autoimmune diseases, asthma, and allergies. Missouri Medicine, 118(5), 453–459. https://pubmed.ncbi.nlm.nih.gov/34658440/
12. Lands, W. E. M. (2005). Dietary fat and health: The evidence and the politics of prevention: Careful use of dietary fats can improve life and prevent disease. Annals of the New York Academy of Sciences, 1055(1), 179–192. https://doi.org/10.1196/annals.1323.028
13. Lands, B. (2014). Dietary omega-3 and omega-6 fatty acids compete in producing tissue compositions and tissue responses. Military Medicine, 179(11S), 76–81. https://doi.org/10.7205/milmed-d-14-00149
14. Rett, B. S., & Whelan, J. (2011). Increasing dietary linoleic acid does not increase tissue arachidonic acid content in adults consuming Western-type diets: a systematic review. Nutrition & Metabolism, 8(1), 36. https://doi.org/10.1186/1743-7075-8-36
15. Johnson, G. H., & Fritsche, K. (2012). Effect of dietary linoleic acid on markers of inflammation in healthy persons: A systematic review of randomized controlled trials. Journal of the Academy of Nutrition and Dietetics, 112(7), 1029-1041.e15. https://doi.org/10.1016/j.jand.2012.03.029
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17. Fritsche, K. L. (2008). Too much linoleic acid promotes inflammation—doesn’t it? Prostaglandins Leukotrienes and Essential Fatty Acids, 79(3-5), 173–175. https://doi.org/10.1016/j.plefa.2008.09.019