Study finds no link between omega 6 and increased inflammation

A new study published in Nutrients offers new insight into omega-6 and whether it is truly the proinflammatory fatty acid many claim it to be.

There is currently a heightened interest in the health effects of seed oils, many of which are rich in linoleic acid (LA), an essential omega-6 fatty acid. Many have claimed that western diets contain “too much” LA and that many diseases of modernity stem from the increased intake of LA over the last century.

This narrative places the blame on excess inflammation presumably caused by higher LA intakes. But are higher intakes – and therefore higher blood levels – really linked with increased inflammation? That was the primary question this new study addressed.

Investigators relied on data from the Framingham Offspring Study, a well-known research cohort from the Boston area. The Framingham Offspring Study is a landmark longitudinal research initiative that follows the children of participants in the original Framingham Heart Study to investigate genetic and lifestyle factors influencing cardiovascular and metabolic health. Launched in 1971, it has provided decades of valuable insights into chronic disease risk and prevention. The cohort’s rigor and continuity make it one of the most trusted sources for understanding long-term health trajectories.

This was a cross-sectional study, meaning that the LA and arachidonic acid (AA) levels were measured in the same blood samples as the 10 inflammation-related biomarkers in 2700 individuals. The relationships between the levels of these two omega-6 fatty acids and 10 separate blood/urine biomarkers of inflammation and oxidative stress were statistically evaluated.

After adjusting (controlling statistically) for multiple other potentially confounding factors (age, race, sex, smoking, blood lipid levels, blood pressure, body weight, etc.), the researchers found that higher LA levels were associated with statistically significantly lower levels of five of the 10 biomarkers, and in no case was higher LA related to higher levels of any biomarker. For AA, higher levels were linked with lower concentrations of four markers, and, like LA, there were no statistically significant associations with higher levels of inflammation/oxidation.

“These new data show clearly that people who have the highest levels of LA (and AA) in their blood are in a less inflammatory state than people with lower levels. This finding is exactly the opposite of what one would expect if omega-6 fatty acids were ‘proinflammatory’ – in fact, they appear to be anti-inflammatory,” explained study investigator William S. Harris, PhD; President Fatty Acid Research Institute; Founder, OmegaQuant Analytics, LLC; and Professor, Department of Internal Medicine, Sanford School of Medicine, University of South Dakota, Sioux Falls, SD.

“In the flurry of news stories about the harms of seed oils – the primary sources of LA in the diet – many voices are calling for reducing Americans’ intakes of LA. This is not a science-based recommendation, and this study – in addition to many more – point in precisely the opposite direction: instead of lowering LA intakes, raising intakes appears to be a healthier recommendation,” Dr. Harris continued. “These findings contradict a narrative, not previous research findings. There are many studies in the medical literature that are consistent with our findings here.”