Seed Oils Explained: What They Are, Health Effects, and Myths Debunked

Seed oils are refined fats pressed from seeds like soybean, canola, corn, safflower, and sunflower. This episode of Scientific American Science Quickly investigates what seed oils are, how they differ from oils like olive or avocado oil, and what the evidence actually says about heart health and inflammation. Featuring Eric Decker from the University of Massachusetts Amherst, the discussion explains fatty acid profiles, real-world data on LDL cholesterol, and why popular claims about seed oils being uniquely toxic are not supported by human trials. It also covers processing details such as hexane extraction and why cheaper seed oils often come with a bland flavor and practical benefits for cooking. The host emphasizes that health messaging should focus on overall fried food intake and cooking practices rather than vilifying seed oils as a universal danger.

Overview

The episode examines the seed oil controversy, distinguishing marketing claims from scientific evidence. It introduces the guests and frames questions about whether seed oils are worse for health than other fats, and what role consumer choices play in cardiovascular risk.

"Seed oils are not inherently toxic, but cooking practices matter" - Eric Decker, University of Massachusetts Amherst.

What are seed oils?

Seed oils such as soybean, canola, corn, safflower, and sunflower oils are typically refined, though some cold‑pressed varieties exist. The fatty acid profile varies by plant, with some seed oils rich in polyunsaturated fatty acids like linoleic acid, while olive and avocado oils are higher in monounsaturated fats. The discussion highlights how refining and genetics shape oil composition and flavor.

"Fatty acid profiles vary by plant, with seed oils often high in polyunsaturated fats like linoleic acid, while olive and avocado oils are higher in oleic acid" - Eric Decker.

Health effects and evidence

Clinical data indicate polyunsaturated fats can lower LDL cholesterol, reducing cardiovascular risk in part by replacing saturated fats. Inflammation theories, notably the omega‑6 to omega‑3 ratio, are discussed, with emphasis on human trials showing linoleic acid does not reliably raise inflammation. The role of processing solvents like hexane and the safety of consumption are addressed, alongside concerns about oil oxidation during frying.

"Clinical data show polyunsaturated fats can lower LDL cholesterol, reducing cardiovascular risk, and human trials do not consistently show increased inflammation from linoleic acid" - Eric Decker, University of Massachusetts Amherst.

Practical guidance for cooking and eating

In everyday cooking, oil choice depends on flavor and usage. Seed oils offer high smoke points and cost advantages, while more flavorful options like extra virgin olive oil are recommended for dressings and low‑heat cooking. The conversation also stresses oil management in kitchens and the broader health message of limiting fried foods rather than demonizing any single fat.

"Oil management and moderating fried foods are key to health, not simply choosing seed oils over other fats" - Eric Decker.