Q&A: Penn State nutritional sciences researcher discusses seed oils’ role in human health

Seed oils like soybean, sunflower, and canola have become staples in modern diets, but are also debated, especially around their high linoleic acid content.

Linoleic acid is an essential omega-6 polyunsaturated fatty acid that has been associated with a lower risk of heart disease and type 2 diabetes in individuals with a higher intake than other dietary fats. Despite its benefits, some health experts and online nutrition influencers have raised concerns about its potential negative effects.

Researchers and experts, like Kristina Petersen, associate professor of nutritional sciences and principal investigator in the Diet and Cardiometabolic Health Laboratory, are conducting research to better understand how different nutrients and foods — like seed oils — impact overall health. Petersen recently published a review paper in Nutrition Today where she and her colleagues reviewed several studies for the health implications of linoleic acid and seed oils to add clarity about their role in human health.

In this Q&A, Petersen discussed the science behind seed oils and linoleic acid and how they are essential to a healthy diet.

Q: What are seed oils and why are people concerned about them?

Petersen: Seed oils are made from the seeds of plants, but most people refer to them as vegetable oils. Some common seed oils are made from canola, soybean, sunflower, and corn. Oils made from fruits such as olive and palm are not considered seed oils.

There is a lot of misinformation on the internet and social media about seed oils. Many of the claims made about the “harms” or “adverse effects” of seed oils are not supported by the totality of the scientific evidence. One commonly expressed concern is that linoleic acid causes inflammation that negatively impacts health, while another concern is that the methods used to process seed oils may negatively alter them or leave harmful residues.

Q: What is linoleic acid and how does it impact the human body?

Petersen: Linoleic acid is an essential polyunsaturated fatty acid. This means we must consume linoleic acid to meet our physiological requirements because humans cannot produce it. Linoleic acid deficiency is rare but can result in rough and scaly skin and dermatitis.

A common claim made about linoleic acid is that it promotes inflammation and oxidative stress. The idea that linoleic acid promotes inflammation is based on its potential to break down into proinflammatory molecules during metabolism. Despite this claim, there is limited scientific evidence to suggest linoleic acid is broken down into proinflammatory molecules or that it increases inflammation. The preponderance of evidence from clinical trials shows that a higher intake of linoleic acid does not increase markers of inflammation or oxidative stress.

Observational evidence shows that a higher intake of linoleic acid is associated with a lower risk of cardiovascular diseases as well as type 2 diabetes. Evidence from clinical trials aligns with this and shows that linoleic acid intake as a replacement for saturated fat improves blood cholesterol levels as well as risk factors associated with type 2 diabetes. Based on this strong evidence, it is recommended to consume sources of polyunsaturated fats instead of saturated fat.

Q: How are seed oils processed and are current processing practices safe?

Petersen: There are several steps involved in producing oils from seeds. Available evidence shows that seed oils in the food supply have extremely low levels of residue from compounds used in processing, such as hexane, that are well below the safety limits established by several regulatory organizations.

Q: What are the recommendations for seed oils and how can they be included in a healthy diet?

Petersen: Vegetable oils — including seed oils — are recommended as part of healthy dietary patterns. These oils should be used in food preparation and cooking instead of solid fats such as butter, beef tallow, lard, palm and coconut oil, which are high in saturated fats and have been shown to be associated with an increased risk of heart disease.

Q: Are you currently investigating any similar avenues of research?

Petersen: My lab is currently conducting research on the health effects of cottonseed oil. The study looks at the effects of a healthy diet containing cottonseed oil on biomarkers of heart and metabolic health compared to other commonly consumed plant oils.

Q: How can people learn more about your ongoing studies or get involved in the research?

Petersen: If anyone is interested in learning more, they can email our lab at DCHLab@psu.edu.

Originally published in June 2025.