In 2018, researchers published a review examining the widely held belief that eating more omega-6 fats from seed oils fuels inflammation.

They analyzed the biological pathway where the body converts these fats into arachidonic acid, which is a building block for inflammatory molecules.

However, when reviewing data from healthy human adults, they found that increasing the intake of these fats did not actually increase the concentration of inflammatory markers in the body.

The researchers noted that epidemiological studies even suggest these fats might be linked to reduced inflammation, directly supporting the claim that seed oils do not cause chronic inflammation.

Scientists systematically analyzed data from 15 randomized controlled trials to test if eating linoleic acid, the main fat found in seed oils, actually causes inflammation in healthy adults.

Across the trials, individuals were assigned to consume differing amounts of this fat over several weeks to months while researchers tracked multiple blood markers of inflammation.

The combined data showed absolutely no significant increases in any inflammatory markers, returning an overall effect size near zero.

The researchers concluded that human clinical trial data definitively shows that adding seed oils to a normal diet does not increase systemic inflammation, proving these oils do not cause chronic inflammation.

The American Heart Association assembled an expert panel in 2009 to evaluate the entire body of nutritional evidence regarding the specific fats found in seed oils.

After analyzing both long-term observational populations and controlled human trials, the panel found no evidence that high intake of these fats increases inflammatory markers in the blood.

Instead, they calculated that consuming 5% to 10% of total daily calories from seed oils actually lowers the risk of coronary heart disease compared to diets with lower seed oil intake.

The advisory explicitly warned that reducing seed oil consumption would likely increase population rates of heart disease, aggressively contradicting the idea that they cause harmful chronic inflammation.

An international consortium of scientists pooled raw biomarker data from 30 observational studies spanning 13 countries to bypass the unreliability of people self-reporting their diets.

By directly measuring the concentration of linoleic acid, the primary seed oil fat, in the blood of 68,659 participants, they found that those with the highest levels actually had better health outcomes.

Specifically, the highest seed oil levels correlated with a 7% lower incidence of total cardiovascular disease and a 22% lower risk of cardiovascular mortality compared to the lowest levels.

Because cardiovascular disease is heavily driven by inflammation, the researchers noted that this massive dataset strongly supports the protective benefits of these fats, indicating they do not cause chronic inflammation.

The American Heart Association published a Presidential Advisory reviewing the most rigorous available clinical trial data on dietary fats, focusing on studies where subjects replaced saturated animal fats with liquid vegetable oils.

By aggregating the data from four core long-term randomized trials, researchers calculated that making this specific dietary switch resulted in a 29% reduction in cardiovascular disease incidence.

The advisory noted that this 29% reduction in heart disease matches the significant benefit typically achieved by taking daily cholesterol-lowering medications.

They concluded that extensive clinical evidence proves replacing solid fats with liquid seed oils protects the vascular system from damage, defying claims that seed oils cause chronic inflammation.