Glossary /
Seed Oils
Industrial vegetable oils — soybean, corn, canola, sunflower, safflower, cottonseed, grapeseed — extracted with heat and solvents.
What it is
Seed oils are pressed and refined from the seeds of plants that, before the twentieth century, were not significant food sources. The extraction involves high heat, hexane solvents, bleaching, and deodorizing. The finished product is mostly polyunsaturated linoleic acid — an omega-6 fatty acid that, in small amounts, is essential, but in modern food supply represents 8 to 10 percent of total calories where it used to be a fraction of one percent.
Why it matters
The debate is not whether linoleic acid is necessary — it is — but whether the current intake is far too high relative to omega-3s, and whether the refining process oxidizes the oils in ways that promote inflammation. The evidence is contested but the direction is clear enough: cooking with butter, ghee, olive oil, or animal fats and minimizing ultraprocessed packaged food is a defensible default, regardless of where the science lands.