Good Oil, Bad Oil: What You Cook With Could Be Helping (or Hurting) Your Health


by Dr. Michael Boss, DC

Good edible fats are essential to great health and wellness. They provide us with energy, help us fight fatigue, sharpen our memory, balance our mood, decrease inflammation, prevent depression, ease arthritis and joint pain, improve skin health, decrease the risk of heart issues, lower cholesterol and triglyceride levels, and curb over-eating as they provide satiety. They also help with blood sugar metabolism issues, prevent neuro-degeneration and much more.

One of the main ways that fats enter our bodies is through oils we use when we cook. You need to know that all oils are not created equal when it comes to health benefits. Most of the oils used in home and restaurant kitchens are really bad for your body.

Heavily Processed Oils

Good healthy oils like olive oil do not just naturally drip out of olives into the bottles and go on the shelves. Oils must be processed or extracted from their sources in one way or another. The more chemical or mechanical processing that goes into the production of an oil, the worse it is going to be for your health. I encourage you to avoid ingesting oils that require industrial processing on a large scale. Most of these types of oils require multiple processes involving chemical additives like hexane, which is a petroleum solvent, in order to put them in the form that goes into a bottle and then into your body.

When Oils Go Bad

All oils will spoil or turn bad with time. They lose their freshness and turn rancid. Oil turns rancid with exposure over time to heat, light and air causing oxidization, which is like rusting. Besides taking on an unpleasant taste and odor, rancid oil also poses certain health risks. Rancid oil usually tastes different, but often you cannot detect it because manufacturers take steps to deodorize the bad smell and taste. Rancid oil forms harmful free radicals in the body, which are known to cause cellular damage and have been associated with diabetes, Alzheimers disease and other conditions. Rancid oils cause digestive distress and deplete the body of vitamins B and E. Ingestion of rancid oils can also cause damage to DNA, accelerate aging, promote tissue degeneration and foster cancer development.

Oil Storage

The way you store your oils is very important. Vegetable oils have already oxidized heavily due to processing, and they continue to oxidize when stored at room temperature. They oxidize even further each time you open and close the cap. Therefore, if you must continue using an oil prone to oxidation, buy it fresh as you need it, in small-enough quantities that you know you’ll finish using as soon as possible. Store all edible oils in a tightly sealed container like dark glass in a cool, dark location like your cupboard.


  • Olive (and variations): Olive oil is a delicious salad oil, a decent sautéing oil, and it can even be used as moisturizer and shaving lotion. You should always have a bottle of extra virgin, cold-pressed olive oil available. It does great cooking with lower heat.
  • Coconut: Coconut oil is a tasty, shelf-stable (no hydrogenation required) tropical oil with a ton of saturated fatty acids. It is almost purely saturated, which is why some doctors might advise against its consumption. Not me. Use it to cook, blend it in protein smoothies or juice, or eat it by the spoonful.
  • Fish: Fish oil is another one of the widely accepted “good” fats. The Omega-3 fatty acids, EPA and DHA, are unequivocally beneficial to us. They help balance our O6-O3 ratios, promote proper cell function, good lipid numbers and improved insulin sensitivity. Use fish oils daily.
  • Avocado: Its fatty acid profile is similar to that of olive oil, but it has an even higher smoke point, making it a decent choice for cooking. Stay on medium to low medium heat. The light, subtle taste is fabulous in salad dressing.


  • Sesame Seed: The premier “flavor oil.” Sesame seed oil, especially the toasted variety, offers an unmatched and irreplaceable flavor profile. Sesame oil also contains a ton of antioxidants that can help minimize heat oxidation. Use it occasionally. 
  • Walnut: Walnut oil is a tasty nut oil. It is high in Omega-6s, so don’t use it often. Buy it in small quantities; a small dash goes great with cooking or in salad dressing.
  • Palm: Palm oil is highly saturated and heat stable. Red palm oil is also stable, but it deserves special mention for its nutrient density.


  • Canola Oil: Canola oil comes from rapeseed, a completely unpalatable seed high in erucic acid, which is bitter and very toxic. Canola oil is rapeseed oil processed and stripped of erucic acid. It is called a “heart healthy” oil rich in healthy Omega-3s, but canola oil processing uses heat of 500 degrees. This causes the major portion of the Omega-3s to become rancid on the shelf before you consume it.
  • Corn: According to the United States Department of Agriculture, 1 tablespoon of corn oil contains 7.239 grams of Omega-6 fatty acids and 0 grams of Omega-3 fatty acids. Omega-6 fatty acids accelerate the growth of cancer cells, such as prostate tumor cells, and tumor growth, whereas Omega-3 fatty acids protect the body from cancer, according to research by Isabelle Berquin published in the “Journal of Clinical Investigation” in 2007. 
  • Peanut: Restaurants like to tout that they use “healthy” peanut oil in their deep fryers. Peanuts are legumes and legume oils go rancid very easily.
  • Sunflower & Safflower Seed: While touted as “healthy,” these oils are high in polyunsaturated fatty acids with little to no Omega-3s to balance them out.
  • Cottonseed: Cottonseed oil is in many food products because it’s cheaper than other oils. It is a “partial hydrogenated” oil which means it is altered to maintain stability and is high in unhealthy trans fat.
  • Grape Seed: This oil gets a lot of hype as a good replacement for olive oil, but it has high oxidation potential.
  • Soybean Oil: Soybean oil is another partially hydrogenated oil, which means it is high in unhealthy trans fat.

Healthy fats are important, and oils are a big source of some of those good fats. I recommend staying in the realm of olive oil, coconut oil, and a little avocado oil. If you want to venture out, a few of the nut oils like walnut are alright in small amounts. As for the rest, avoid them like a two-lane highway at rush hour. Get your good, healthy fats in you and enjoy a healthy life.

Dr. Michael Boss has been a practicing chiropractor and wellness practitioner for more than 20 years. He is co-founder and president of Elevate Life, and he provides treatment programs that focus on functional healthcare, nutrition, acupuncture, exercise, hormone function and balance, chronic diseases, nutriceuticals and more. He also co-hosts the weekly ELEVATE LIFE Wellness Hour on 550 KTSA. Call 210-264-2570 for an individual consultation, or visit to learn more.

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