Myth-busting study shows controversial seed oils reduce inflammation

Linoleic acid, which is found in vegetable oils -- especially seed oils like soybean and corn oil -- and plant foods, is the primary omega-6 fatty acid consumed in the diet.

"There has been increasing attention on seed oils, with some claiming these oils promote inflammation and raise cardiometabolic risk," said Kevin C. Maki, Ph.D., adjunct professor at the Indiana University School of Public Health-Bloomington and chief scientist at Midwest Biomedical Research. "Our study, based on almost 1,900 people, found that higher linoleic acid in blood plasma was associated with lower levels of biomarkers of cardiometabolic risk, including those related to inflammation."

Maki presented the findings at NUTRITION 2025, the flagship annual meeting of the American Society for Nutrition held in Orlando, Florida.

The new results are consistent with those from observational studies that have shown higher intake of linoleic acid to be associated with lower risks for type 2 diabetes and cardiovascular events, such as heart attacks and strokes.

"Although other studies have assessed relationships between linoleic acid and cardiometabolic risk factors, our study used objective biomarkers rather than diet records or food frequency questionnaires to assess linoleic acid intake," said Maki. "We also measured a range of markers of inflammation and indicators of glucose metabolism."

For the new study, the investigators performed a cross-sectional analysis on data from 1,894 people in an observational cohort focused on Covid-19. They found that higher levels of linoleic acid in plasma -- indicative of dietary intake -- were consistently associated with lower levels of risk factors for cardiovascular disease and type 2 diabetes.

Specifically, study participants with higher linoleic acid showed lower levels of glucose and insulin as well as HOMA-IR, a biomarker of insulin resistance. They also had lower levels of inflammation biomarkers, including C-reactive protein, glycoprotein acetyls, and serum amyloid A.

"We saw consistent results across the different biomarkers measured," Maki said. "People with higher levels of linoleic acid in their blood tended to have a healthier overall risk profile for heart disease and diabetes."

The researchers say that their findings support the need for additional intervention studies to test whether increasing linoleic acid intake improves cardiometabolic risk factors and lowers the incidence of heart attacks, strokes and type 2 diabetes. Next, they plan to investigate how different types of oils with varying fatty acid content affect cardiometabolic risk factors.