Diet & Nutrition

8 Bad Seed Oils You Should Replace

What's the most powerful dietary change you can make? According to one prominent doctor and author, the answer is cutting out vegetable oils

Do you ever feel mentally exhausted during the day, even if you’ve had enough sleep? Do you get cranky or unable to function before lunch or mid-afternoon, until you eat something? Or maybe you’re having a hard time learning how to use a new electronic device and chalk it up to “getting old.”

These are just some of the symptoms of eating unhealthy seed oils (aka vegetable oils), according to Catherine Shanahan, MD, best known as Dr. Cate and author of The Fatburn Fix and Deep Nutrition. Other side effects of such fats can include weight gain, anxiety, mood problems, migraines, and other types of headaches.

Seed oils are the most common fats in foods that come in packages and on restaurant menus and they make up the largest share of fat in the typical American diet. But this doesn’t make them healthy.

Many people eliminate gluten or other foods or try to reduce sugar to improve their health and performance. But they’re missing a more basic step.

“If they don’t first cut out all 8 vegetable oils, it’s like taking an aspirin for a headache before deciding to stop hitting themselves on the head with a hammer,” says Dr. Cate. And the idea of “everything in moderation” does not apply.

See also: The Laker’s Diet

8 Harmful Seed Oils

These are the most widely used, unhealthy fats:

  • Canola oil
  • Corn oil
  • Cottonseed oil
  • Grapeseed oil
  • Rice bran oil
  • Safflower oil
  • Soy oil

Although they are usually refined, even unrefined and cold-pressed versions pose the same health risks because these oils are naturally rich in polyunsaturated fats: PUFAs. The molecular structure of PUFAs makes them very unstable in the human body and they generate a tremendous amount of free radicals — chaotic reactions that damage cells.

Free radicals are a normal byproduct of metabolism that our bodies are equipped to handle, but only up to a point. Seed oils produce an onslaught that far exceeds our innate capacity.

“Free radicals are bad for us in the same way that radiation is bad for us,” says Dr. Cate. When you eat a lot of PUFA-rich seed oils, she adds, “It’s like you have tiny dirty bombs inside your cells.”

PUFAs are inflammatory and damage the lining of blood vessels, affecting overall circulation, blood flow to the brain, and risks for heart disease and diabetes.

According to a review of research published in Mayo Clinic Proceedings,[i] health hazards of eating too many of these oils include a suppressed immune system; lower “good” HDL cholesterol; a more dangerous, oxidized form of “bad” LDL cholesterol; and increased risk for prostate, pancreatic, colon, and breast cancers.

Are Seeds Harmful?

Although seed oils are rich in PUFAs, whole seeds also contain other fats, fiber, and important vitamins, minerals, and antioxidants. Whole (or ground) seeds are nutritious foods.

Benefits of Eliminating Seed Oils

“It’s like a fog has lifted.” That’s what many people tell Dr. Cate after they stop eating seed oils.

Other benefits include unlocking the ability to burn body fat; fewer headaches; a better mood; less anxiety; greater ability to learn new things; and overall enhanced mental performance.

Less craving for sugar is another perk. “The gateway drug to sugar addiction” is one of her descriptions of the harmful fats because when you eat them, the combination of locked-up body fat and depleted mental energy makes you reach for junk food — especially the sugary or starchy kind.

Good Fats

Refining turns good oils bad, so oils should be both cold-pressed and unrefined. These are Dr. Cate’s top choices of multipurpose fats that can be eaten cold and used for all types of cooking:

  • Almond oil
  • Avocado oil
  • Butter
  • Cocoa butter
  • Coconut oil
  • Ghee
  • Macadamia nut oil
  • Olive oil
  • Peanut oil
  • Tallow and lard

Hemp culinary oil can be eaten cold or used for low-heat cooking. Flax and walnut oils are healthy fats that shouldn’t be exposed to heat.

Shopping Tips

Organic versions of harmful seed oils are becoming more popular in packaged foods. Organic standards help to reduce toxins from chemicals used in agriculture and refining, but they don’t change the molecular structure of PUFAs, so organic versions of the unhealthy seed oils will produce the same harmful reactions in the human body as regular versions.

Healthy fats degrade when they are refined and can go rancid during shipping or storage. Look for fresh, unrefined, cold-pressed products.