by Mila McManus, MD

The most popular culinary chefs on your cooking channel are likely proponents of cooking in plant oil {vegetable or seed oil], such as olive, avocado, peanut, grapeseed, sesame, or canola oil.   Most hot preparation recipes call for one of these.  Many chefs will attribute a high smoke point and light flavor as culinary benefits to using them. But is it healthy?

Industrially Manufactured -What is a high smoke point oil? High smoke point oils are produced by manufacturers using industrial refinement processes such as bleaching, filtering, and high-temperature heating. The refinement process serves to extract and eliminate the extraneous compounds that burn, or smoke, at a certain point. This also makes the oil shelf-life longer[1]. This industrial refinement applies to most of the oils labeled “high smoke point” including avocado, canola, cottonseed, grapeseed, olive, peanut, safflower, soybean, and sunflower oils. Refinement increases manufacturers’ profitability while making them more pro-oxidative, pro-inflammatory, toxic, and nutrient deficient[2].

Damaged and Adulterated – Cooks are focused on taste – not necessarily on what is in the best interest of your body. Light, heat, water, and air are enemies of cooking oils. For this reason, it doesn’t make health-sense to cook with them. Whether cooking with high temperatures for short duration [think searing a roast in a pan at 375-400°], or lower temperatures for a longer duration [think roasting vegetables for 30 minutes at 350° or higher], heat will breakdown and destroy these cooking oils. They are not structurally secure chemical formulas. There is considerable speculation that, much like olive oil and grapeseed oils, avocado oil is also being refined, tainted, and blended with cheaper seed oils.  At this point, it’s difficult to discern a clean, unadulterated oil from a damaged one on the grocery store shelf. Carefully selected unrefined olive and avocado oils are healthy choices for cold preparations which allow  you to reap the natural, unadulterated benefits of these mostly mono-unsaturated fats.

Toxic to Cells – Research is revealing how toxic these oils are to your mitochondria, the organelles found in every cell in your body necessary to produce energy and keep the cell alive and functioning[3]. Research suggests refined vegetable/seed oils [i.e. avocado, canola, cottonseed, grapeseed, olive, peanut, safflower, soybean, and sunflower] are implicated in the rise of lifestyle diseases of today, including cancer, cardiovascular disease, diabetes, and obesity. These oils are found in all processed foods, fast food, and most restaurant food[4]. They are on the oil aisle touted as high smoke point options.

Omega 3:6 Ratios – Vegetable/seed oils are also extremely high in omega-6 fats, even when fresh from the source. While we need omega-6 fats, they are very easy to get from our diet. Most people eating the standard American diet, which is highly processed, consume five times more omega-6 fats than omega-3 fats, creating excess oxidation, inflammation, and toxicity. One good example of a common health outcome of eating too many Omega-6 fats is excess LDL cholesterol and a high total cholesterol.  Lowering omega -6 fats in the diet and increasing Omega-3 fats contribute important antioxidant, anti-inflammatory benefits for the whole body and can lower LDL cholesterol and improve total cholesterol. But omega-3 fats are much more difficult to get through the diet.  Getting the proper balance of Omega-3 to omega-6 oils requires action from both aspects: reduction of vegetable/seed oils high in omega-6 fats and increases in quality sources of omega-3 fats such as wild anchovies, mackerel, herring, and cod liver oil, as well as grass-fed beef, pasture raised eggs, walnuts, and appropriate supplementation[5].

Carcinogenic Potential – The smoke point of an oil, also known as the burn point, is where the oil breaks down and releases free radicals and a substance called acrolein, the chemical taste and smell of burnt oil. Acrylamide is the common substance released from burnt plant foods such as potatoes, found to be cancer causing in mice[6]. Extremely high heat cooking will most likely result in oxidation and release of toxic acrylamides from the food being cooked. So whether it’s from the oil, or the food being cooked, the natural structure of both the oil and the food [meat, veggie, egg, etc.] are also being de-natured, reducing its nutrient value and increasing its toxicity. It’s best to minimize high heat cooking.

Solutions – Use saturated fats for medium high, medium, and low heat stovetop, roasting, and baking. Saturated fats, which are solid, not liquid, at room temperature, are structurally double bonded chemical formulas. That is what gives them their solid nature. They tolerate light, heat, and air much better than the oils already mentioned above. Our earlier ancestors left butter on the counter all the time. They are also generally lower in Omega 6 content, and higher in Omega 3, less easily oxidized, and less inflammatory or pro-oxidative. They are good for brain and heart health and promote absorption of important fat soluble vitamins like A, D, E, and K which promote healthy bones, skin, and vision, just to name a few. They tolerate heat better for longer periods of time, offer better nutrition, and are not industrially refined  in the first place. Start with an undamaged oil the way it is found in nature such as ghee, butter, beef tallow, pork or chicken fat, and coconut oil. Ideally, animal fats should come from animals that ate their natural diet grazing and foraging, and should be organic whenever possible. All animal fats have a smoke point equal to or higher than avocado or olive oil. The French are well known for cooking in duck fat. The flavor is delightful.

Cook wisely. Be Well.

[1] https://www.seriouseats.com/cooking-fats-101-whats-a-smoke-point-and-why-does-it-matter#toc-chart-smoke-point-index

[2] Knobbe, Chris A. (May 14, 2023). The Ancestral Diet Revolution. Ancestral Health Foundation.

[3] Rogers, Kara. (January 9, 2024) Science & Tech: Mitochondrion. Encyclopedia Britannica. https://www.britannica.com.

[4] Knobbe, Chris A. (May 14, 2023). The Ancestral Diet Revolution. Ancestral Health Foundation.

[5] https://www.healthline.com/nutrition/12-omega-3-rich-foods. Updated October 6, 2023. Accessed 1/18/2024.

[6] https://www.cancer.net/blog/2023-01/can-eating-grilled-or-charred-foods-cause-cancer