Every decade has a new food enemy. First, it was fat. Then, it was sugar. Now, seed oils are under fire—blamed for causing obesity and chronic disease.
They’re almost impossible to avoid. Seed oils are in everything—from salad dressings and fast food to protein bars and even baby formula. Critics claim they’re harmful, while supporters argue they’re safe, affordable, and even good for you.
However, the truth is more nuanced. The debate is often oversimplified. Even the term “seed oil” is misleading, lumping together oils that have been part of traditional diets for centuries with those created for large-scale food production.
What Are Seed Oils, Really?
If you’ve been following health trends, you’ve probably heard claims that seed oils are toxic and should be avoided. What exactly are seed oils, and why do some people consider them harmful?At their most basic, seed oils are extracted from seeds. This might seem harmless—after all, olive oil comes from olives, and coconut oil from coconuts.
But not all seed oils are the same. Some, like sesame and flaxseed oil, have been integral to traditional diets for centuries and are extracted through natural, cold-press methods that preserve their nutrients and antioxidants.
Others, however, are highly processed. Industrial seed oils—like soybean, corn, canola, sunflower, safflower, cottonseed, grapeseed, and rice bran—are mass-produced through high-heat extraction and chemical refining.
Manufacturers frequently use solvents like hexane to extract the maximum amount of oil. These oils are refined, bleached, and deodorized, earning them the label “RBD” oils. This process makes them neutral in taste and more shelf-stable, but it also removes beneficial compounds like vitamin E and antioxidants.
Many industrial seed oils were never intended for human consumption. Canola oil began as rapeseed oil, primarily used as a machine lubricant until Canadian scientists modified it in the 1970s to remove toxic compounds. The name itself—a blend of “Canada” and “oil”—was a marketing invention. “Vegetable oil” is another misleading term—it’s often a blend of industrial seed oils marketed to sound healthier than it is.
Cate Shanahan, a Cornell-trained physician-scientist specializing in dietary fats, explains that industrial seed oils were not developed with nutrition in mind.
“The crude oil from these seeds is inedible,” she told The Epoch Times. “Soy and canola weren’t bred for nutrition—they were bred for high yields and industrial durability.”
Unlike traditional oils such as olive or sesame, which retain their natural antioxidants, industrial seed oils require extensive refining to become shelf-stable. Shanahan argues that this process removes beneficial compounds, making them more prone to oxidation and degradation.
Are Seed Oils Good or Bad for Your Health?
Seed oils’ health effects are hotly debated. Some experts say they’re a heart-healthy alternative to butter and other animal fats, while others believe they might contribute to inflammation and disease.The Case for Seed Oils As a Heart-Healthy Alternative
For decades, scientists have debated the role of different fats in heart health. Research suggests that replacing saturated fats—found in butter and red meat—with polyunsaturated fats (PUFAs) from seed oils may offer cardiovascular benefits.Advocates argue that the science is well-established.
“The research on seed oils is consistently positive,” Matthew Nagra, a naturopathic doctor, told The Epoch Times. “Numerous meta-analyses of randomized controlled trials have demonstrated that replacing saturated fat with seed oils rich in polyunsaturated fats can lower the risk of cardiovascular disease, America’s top killer, without any clear detriment.”
“Our findings support shifting the intake from solid fats to non-hydrogenated vegetable oils for cardiometabolic health and longevity,” the authors wrote. Examples of solid fats include butter and lard.
The Case Against Seed Oils: Oxidation and Inflammation
Not everyone agrees with the AHA’s endorsement of seed oils, and some experts question the research behind it.“This study is of low quality,” Dr. Vinay Prasad, a hematologist-oncologist and professor of epidemiology and biostatistics at the University of California, San Francisco, told The Epoch Times in an email. “It lumps extra virgin olive oil with soybean and safflower oil, which is ridiculous.” He also criticized the study’s methodology, arguing that it fails to accurately measure butter consumption and instead relies on an imprecise estimation method. “This kind of nutritional epidemiology fuels dogma rather than providing clarity,” he said.
Beyond concerns about research methods, critics argue that the real issue with seed oil is oxidation.
Refining makes seed oils more resistant to spoilage, allowing them to last longer on store shelves. However, once exposed to heat, air, or light—especially during cooking—their chemical structure begins to break down.
Not all experts agree that oxidation is a major threat.
“These processes have pros and cons,” says Christopher Gardner, a nutrition professor at Stanford. “They help prevent oils from breaking down but also strip away some beneficial components.”
The Processed Food Connection
If there’s one thing both critics and defenders of seed oils agree on, They’re everywhere. And that’s no accident.Cheap, abundant, and heavily subsidized seed oils are a pillar of the modern food industry. The U.S. government pours billions into supporting crops like soybeans, corn, and cottonseed, making their oils far more affordable than alternatives like olive or avocado.
Government support doesn’t just make seed oils cheap for home cooks—it makes them the backbone of ultra-processed foods (UPFs), which now make up nearly 60 percent of the American diet. Along with refined grains and added sugars, seed oils form the foundation of modern processed foods, used to enhance texture, extend shelf life, and boost flavor at a low cost. These ingredients appear in everything from breakfast cereals to frozen dinners, making them nearly impossible to avoid in a typical supermarket.
A 32-ounce bottle of canola oil costs about $5.79, while the same amount of extra virgin olive oil can cost $13.99 or more. For food manufacturers trying to keep costs down, the choice is obvious. Because they’re inexpensive, neutral in flavor, and relatively shelf-stable, seed oils are a food manufacturer’s dream—allowing processed foods to last longer, taste better, and remain profitable.
Shanahan estimates that seed oils account for 20–30 percent of the average American’s daily calorie intake. This figure wasn’t easy to calculate, as seed oils aren’t tracked as a category. Shanahan analyzed decades of production data from crops like soybeans and canola, using government and industry reports to uncover the extent of seed oils’ presence in modern diets.
“Humans have never consumed polyunsaturates at this level before,” she warns. “Historically, diets relied mainly on animal fats, not oils rich in PUFAs. If you don’t know to avoid them, you’re eating vast quantities.”
Gardner agrees—but says the issue isn’t just seed oils. The rise in seed oil consumption isn’t because more people are making homemade salad dressings, he said. It’s because ultra-processed foods—where these oils are used heavily—now dominate the American diet.
Gardner argues that even if seed oils were removed from the food supply tomorrow, ultra-processed foods wouldn’t disappear—they’d just be reformulated.
“If the same UPFs were made with another oil like butter, beef tallow, lard, or coconut fat, those foods would not suddenly become health foods.”
So, What Should You Cook With?
Rather than fixating on eliminating seed oils altogether, experts say the bigger issue is reducing ultra-processed foods and choosing high-quality, stable fats when cooking at home.“If you want to improve your health by cutting back on seed oils, the best way to do that is by eating fewer ultra-processed foods,” Gardner advises. “That would be a win in several ways—less sugar, less refined grain, and less sodium.”
Better Options for Cooking
- Avocado: High in monounsaturated fats, stable for high heat
- Extra virgin olive: Rich in antioxidants, ideal for drizzling or light cooking
- Butter and ghee: Naturally stable for high-heat cooking
- Coconut: High in saturated fat, making it oxidation-resistant
Oils Best Used Cold
- Flaxseed: High in omega-3s, best for dressings
- Walnut: Antioxidant-rich, flavorful in salads
- Sesame: Aromatic and moderately heat-stable
Industrially Refined Oils
- Soybean
- Corn
- Canola
- Cottonseed
- Sunflower
- Safflower
- Grapeseed
- Rice bran
The Bottom Line
The debate over seed oils is far from over, but one thing is clear: How you consume them matters.A drizzle of canola oil on a homemade salad is not the same as eating French fries fried in old restaurant oil. Relying on ultra-processed foods filled with cheap oils, sugar, and additives is where the larger problem lies.
For most people, the best way to improve their diet isn’t to worry about every drop of seed oil—it’s to eat more fresh, unprocessed foods, says Gardner.
“It seems bizarre to blame the plant oils and not the foods they’re in.”
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