News
4 July, 2025
Fight over fats
Long considered beneficial in fighting inflammation, omega-3 fatty acids may in fact increase certain inflammatory markers in the body, new research suggests.
Dr Daisy Crick from The University of Queensland’s Institute for Molecular Bioscience led the study as part of her PhD research at the Medical Research Council (MRC) Integrative Epidemiology Unit at the University of Bristol. She said the findings challenge long-held assumptions.
“We tend to regard omega-3 as anti-inflammatory and omega-6 as pro-inflammatory, but the relationship is more complex,” Dr Crick said.
“Surprisingly, we found omega-3 fats could increase certain markers of inflammation in the body.”
These findings were drawn from the long-running Avon Longitudinal Study of Parents and Children, which has followed participants from birth into adulthood over three decades. Researchers measured blood biomarkers to assess inflammation and found higher levels of omega-3 fats—naturally found in oily fish and commonly taken in supplements—were linked to higher levels of inflammation.
The association remained even after adjusting for triglycerides and LDL (‘bad’) cholesterol.
The study also found that a higher ratio of omega-6 to omega-3 fats correlated with increased inflammatory markers, suggesting an imbalance may contribute to inflammation.
Dr Crick said the results were backed up by findings from the UK Biobank, a separate dataset of nearly half a million people. Researchers used Mendelian randomisation—a method that uses genetic information to mimic a randomised trial—to confirm the association.
“Our findings suggest that the link between dietary fats and inflammation is more nuanced than previously believed. The balance between omega-6 and omega-3 in the diet may be more important than the absolute amount of either,” Dr Crick said.
While omega-3 fats have long been promoted in popular diets such as the Mediterranean diet and are a staple of over-the-counter supplements, Dr Crick said assumptions about their anti-inflammatory effects may not hold in all cases.
Senior author Dr Hannah Jones from the University of Bristol agreed the results raised new questions.
“Although our findings show that omega-3 fats are associated with increases in some inflammatory biomarkers, they don’t rule out other potential health benefits,” she said.
The study is published in the International Journal of Epidemiology.
