University of Queensland researchers have identified a surprising association in a dataset of over 15,000 individuals: increased levels of omega-3 and omega-6 fatty acids linked with higher concentrations of GlycA, a biomarker used to measure chronic inflammation.
Researchers Apply Genetic Methods to Strengthen Findings
The findings, published in The International Journal of Epidemiology, used Mendelian randomisation to assess whether dietary fats actively cause inflammation rather than simply correlate with it.
Drawing on two major UK-based cohorts—the Avon Longitudinal Study of Parents and Children (ALSPAC) and the UK Biobank—the study offers one of the most robust analyses to date of the causal relationship between fatty acids and inflammation.
“Surprisingly, the results showed that both omega-3 and omega-6 fatty acids were associated with higher levels of a marker called GlycA… This was unexpected, especially for omega-3s, which are widely promoted as anti-inflammatory,” said Dr Thomas M. Holland, physician-scientist at RUSH University, who was not involved in the research.
Skewed Omega Fat Ratios Elevate Inflammatory Markers
Researchers also examined the ratio of omega-6 to omega-3 fatty acids, which has shifted dramatically in modern diets. Once balanced at 4:1, today’s ratios—often nearing 20:1—are influenced by high consumption of seed oils. In the ALSPAC cohort, those with higher omega-6:omega-3 ratios showed consistently elevated levels of CRP, IL-6, and GlycA.
“This [finding] supports earlier findings that it’s not just about how much omega-3 you consume; it’s about how balanced your overall intake is,” Holland added.
Researchers Urge More Nuanced Interpretation of Omega Fats
Lead author Daisy Crick from the Institute for Molecular Bioscience at the University of Queensland emphasised that the findings do not mean omega-3s are inherently harmful, but that their role is more complex than previously understood.
“Our findings suggest that it’s not as simple as ‘omega-3 is anti-inflammatory, and omega-6 is pro-inflammatory’… Improving the balance between the two fats could be a better method for people who want to reduce inflammation in their bodies,” Crick said.
The researchers measured levels of omega-3 and omega-6 in the blood using biomarkers such as DHA and linoleic acid, and assessed inflammation using CRP, IL-6, and GlycA. They acknowledged limitations in the scope of biomarkers examined despite controlling for socioeconomic and lifestyle factors.
“The immune system is incredibly complex… More research using a broader range of immune biomarkers will help clarify this relationship,” said Holland. Crick pointed to the limits of the analysis, saying, “The relationship between fatty acids and inflammation is complex and our findings only tell part of the story.”