Are Seed Oils Making You Sick? This MD Explains The Science

If you've been hearing more about seed oils lately, you're not alone. 

Once hailed as heart-healthy staples, oils like canola and soybean are now under fire—and leading the charge against them is Cate Shanahan, M.D. A board-certified family physician and leading voice in nutrition, Shanahan warns that certain oils lurking in our diets are fueling chronic disease.

Why are these oils so problematic? It all comes down to their chemical structure and how they're processed. These oils are high in polyunsaturated fats, which are unstable and prone to oxidation1.

Seed oils aren't just empty calories—they actively harm the body. Shanahan explains that these oils contribute to2 metabolic diseases, chronic inflammation, autoimmune disorders, and even degenerative conditions.

The problem stems from oxidative stress. The unstable fats in seed oils break down into harmful byproducts that damage cells and trigger inflammation. Over time, this leads to insulin resistance, heart disease, and other metabolic disorders.

And it's not just about what these oils do but also what they lack. Through heavy industrial refining, seed oils are stripped of essential nutrients and antioxidants that help stabilize fats.

Even the most health-conscious eaters will inevitably consume some seed oils—it's nearly impossible to avoid them entirely. The goal isn't to stress over every bite or say no to your favorite foods but rather to be informed and intentional about your choices.

While the debate around seed oils continues, being mindful of the types and amounts of oils in your diet can be a valuable step toward supporting your overall health.

Experts, such as Shanahan, believe swapping these oils for healthier, stable fats isn't just a diet change—it's an investment in your metabolic health and longevity.