Vegetable Oils: The good, the bad, & the ugly.

4 Minute Read

Vegetable oils are everywhere - from sauces to baked goods to your body lotion. What is a vegetable oil? Should they be in your diet or should you totally avoid them? Let’s find out!

Any vegetable oil is a fatty oil extracted from a seed or fruit. Common vegetable oils you’ll encounter in your diet are avocado, coconut, corn, olive, peanut, rapeseed, soybean, safflower, sunflower and canola.

Hmmmm, what on earth is a canola? Is it a plant? A flower? Does it have a seed? While you ponder what a canola is, let’s first talk about how a seed or fruit is made into an oil.

The quality of an oil is determined by the purity of the plant origin AND how the oil is actually processed. So, some oils are considered organic, pure and unrefined where others are genetically modified (GMOs) and are very highly processed. Take a guess which one of those is the healthier option for your body!

Oil extraction starts with the seed or fruit being ground into a coarse meal - essentially, the seeds or fruit is cracked open and then crushed or ground. The coarse meal is then pulverized and then pressed or processed. The processing and pressing of the coarse meal is the MOST important step that determines whether your vegetable oil will end up healthy for your body.

For the healthiest option, your oils should be cold-pressed. Cold pressing involves pressing the oil out of the coarse meal that was made during the pulverizing process. As the oil is pushed out, it will be collected essentially through a sieve. Cold pressing oils maintains their flavor as well as their nutrients. For oils that are not cold-pressed, they will be heated during the extraction process. Heating the coarse meal ends up destroying the nutrient-dense oil AND makes them more harmful to the body. Bye-bye to the quality of the oil!

The next best option is expeller-pressed oils. The coarse meal will be squeezed through a barrel-like apparatus causing friction and resulting in some heat being generated. These oils end up being heated to slightly higher temperatures compared to cold-pressed oils. Again, the heat can damage the quality of the oil.

Oils that are harmful to the body are the ones that are exposed to chemicals and high temperatures during the extraction process. Oftentimes, the coarse meal is exposed to chemicals, like hexane, followed by degumming, neutralization, dewaxing, bleaching, filtration and deodorization, and possibly hydrogenation. These processes degrade the oil causing it to become rancid. Would you want your cells to be built from rancid products? A rancid oil is NOT a healthy oil!

So, how do you determine the quality of your vegetable oil - is it cold-pressed? Expeller-pressed? Or, chemically processed? You are in luck, high quality oils will be clearly labeled. Rest assured, any high-quality oil will have it’s process clearly listed on the label. Here is a quick cheat-sheet for your next purchase:

  • cold or expeller pressed
  • organic
  • unfiltered
  • unrefined
  • virgin

  • cold or expeller processed
  • hydrogenated/partially hydrogenated

Now let’s get back to canola oi! Canola oil is made from genetically modified rapeseed and it is highly processed. Canola oil should ALWAYS be avoided. You should also avoid corn, rapeseed, and soybean oils as these are typically quite processed.

So, stick to the unrefined and heart healthy vegetable oils categories listed above. Typically, oils like coconut, olive, avocado, peanut, safflower and sunflower oils can be used if properly produced. However, beware that some of these oils do go through refinement and chemical processing so always read your labels.

Another warning for your vegetable oils, be careful what temperature you heat these oils to while cooking with them. Coconut oil is best used for high heat cooking up to 350°F and medium to high heat when sautéing. Olive oil is best for sautéing at lower temperatures. The other vegetable oils are best used cold for dressings.

  1. “Vegetable Oil.” Merriam-Webster, Merriam-Webster,
  2. Know Your Fats: the Complete Primer for Understanding the Nutrition of Fats, Oils and Cholesterol, by Mary G. Enig, Bethesda Press, 2000, p. 148.
  3. Broaddus, Hannah. “The Difference Between Solvent Expelled, Expeller Pressed and Cold Pressed Oil.” Non-GMO & Organic Oil Supplier & Packer, 17 July 2017,
  4. Sionek, B. “Cold Pressed Oils.” Roczniki Panstwowego Zakladu Higieny, U.S. National Library of Medicine, 1997,
  5. Know Your Fats, p. 9.
  6. Axe, Josh. “Coconut Oil: 20 Health Benefits, Nutrition and Popular Uses.” Dr. Axe, 24 Apr. 2019,
  7. Staying Healthy with Nutrition the Complete Guide to Diet and Nutritional Medicine, by Elson M. Haas and Buck Levin, Celestial Arts, 2006, p. 529.
  8. Vargas, M. “Expeller Pressed vs. Cold Pressed: Which Type of Oil Should you Choose.” Spoon University,
  9. Wiltz, J. “What is Cold Pressed Oil?” Live Strong.

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