First developed in 1756, mayonnaise began as a simple emulsion of egg, acid, and olive oil. Today, it has become one of the biggest delivery vehicles for refined seed oils in the American diet—even when the front label says, “Made with olive oil.” Turn that jar around, and you’ll often see soybean oil, canola oil, or both in the ingredient list alongside olive oil.
What Are Seed Oils?
Seed oils are highly processed vegetable oils extracted from seeds such as soybeans, canola, corn, sunflower, safflower, grapeseed, rice bran, and cottonseed. These oils are high in omega‑6 fatty acids, including linoleic acid. While the body needs some omega‑6, modern diets deliver far more than we’re designed to handle, often crowding out anti‑inflammatory omega‑3 fatty acids.In modern diets, seed oils are nearly everywhere, from restaurant frying oil to packaged snacks, salad dressings, and many “healthy” foods. Seed oils undergo heavy chemical refining, and in restaurants, they are often heated to high temperatures and reheated repeatedly. When seed oils are overheated and reheated, they break down, forming harmful compounds, including oxidized fats and toxic aldehydes. These damaged molecules can increase oxidative stress and place a burden on the body.
