Navigating the nutritious qualities, multiple varieties, cooking/food prep applications, and the heating process of cooking oils can be a challenging task. A good starting point is knowing what cooking oils are composed of — basically fats, either nutritionally healthy or unhealthy.

Nutritional Considerations

The two types of unhealthy fats are saturated fats and trans fats. Monounsaturated and polyunsaturated fats are generally considered to be healthy fats.

• Saturated fat. These are solid at room temperature and are found in: 
  • milk products such as yogurt, ice cream, and cheese
  • pastries and cakes
  • fried foods
  • coconut oil, palm oil, and palm kernel oils lard
  • animal sources like bacon fat, fatty cuts of red meat, cured meats, and poultry skins (Sacks, Lichtenstein, & Wu, 2017)
• Trans fats. Trans fats are a byproduct of hydrogenation — a process of the chemical addition of “atoms of hydrogen to unsaturated fat, eliminating the double bonds between carbon atoms . . . making them saturated” (Marchand, 2010). The food industry uses this chemical process to prolong shelf life for processed and packaged foods. Anytime you see the words “partially hydrogenated oils,” this means the product contains trans fats. Elevated cholesterol levels and weight gain are the primary detriments of saturated and trans fats to human health.
• Monounsaturated fats. These are defined as fat molecules with one unsaturated carbon bond in the molecule (American Heart Association, 2023). They are usually liquid at room temperature but solidify when cooled. These fats are found in foods such as olives, avocados, and nuts, and cooking oils derived from them.
• Polyunsaturated fats. These fats contain two or more double carbonated bonds in the molecule. The two types of polyunsaturated fats are omega-6 and omega-3 fatty acids. They are also typically liquid at room temperature and harden when chilled. They are found in: 
  • many cooking oils, such as corn and sunflower oils
  • oily fish, such as salmon, herring, tuna, and mackerel
  • walnuts, chia, and flaxseeds

Varying your cooking oils will elevate and vary nutrient absorption. However, cooking with omega-3 and omega-6 fatty acids will promote a more anti-inflammatory and healthier diet (Cleveland Clinic, 2023).

Defining Refining Processes

With many types of monounsaturated and polyunsaturated oils desirable for cooking, another consideration is the extraction and refinement process (Forrest, 2024). 

Unrefined and Cold-pressed Oil

Unrefined and cold-pressed oils are extracted mechanically by crushing seeds or nuts in a rotating screw within a cylinder, without the use of heat or chemicals, maintaining a temperature below 120 degrees. The oil is then filtered without refining and has the following characteristics: 

• Minimum processing 
• Reserves increased nutrients and polyphenols
• May retain sediment particles
• Less resilient than refined and expeller-pressed oils 
• Best for lower-heat baking, cooking, and sautéing (200-400°F)
• May spoil more quickly

Refined and Expeller-pressed Oil

Expeller-pressed oil is also created using a mechanical screw press to extract oils from nuts or seeds. The primary difference is the temperature during the process, as expeller pressing utilizes friction to generate heat of up to 470 degrees.
Another method used to refine oils is by chemical solvents, where seeds or nuts are ground into a paste and then “washed with a solvent such as hexane to release the fats” (La Tourangelle, 2021). After the solvent separates out the oil, it is refined, bleached, and deodorized and has the following characteristics:

• Consistent appearance
• More economical
• Higher smoke point, making them best for high-heat cooking (425–575°F) (Gharby, 2022).

Calefaction and the Smoke Point

Calefaction is defined as temperature rising, or heating. Calefaction in cooking oils can lead to a temperature that causes oil to start producing smoke — the “smoke point” — which causes it to oxidize, producing toxic fumes and free radicals. Free radicals are unstable molecules that cause chemical changes in a cell and prompt “damage to other molecules like DNA, lipids, and proteins” in the body (National Cancer Institute, n.d.). This also causes dangerous fatty-acid production. Finally, the oil emits acrolein, which results in a burnt flavor and is hazardous to breathe into your lungs (Kunik & Panoff, 2023). This all happens when heated oil has a lower smoke point.

Some oils have higher smoke points and can be used at higher heats. Oils with lower smoke points must be used at lower heat, and some oils should not be heated at all. Oils with the highest smoke point are typically the most refined (Cleveland Clinic, 2023).

Most saturated fats have a smoke point of 250–450°F, making them suitable for sautéing, baking, and roasting. Ultimately, unsaturated oils that can tolerate higher cooking temperatures are healthier choices (Gold & Leffler, 2024).

Oil Applications

Pan frying, deep frying, roasting, and baking all need a type of oil or fat for preparation, lubrication, flavor enhancement, binding, and/or moisturizing. Oils (fats) may help:

• Enhance flavor with their own particular flavors.
• Project aromas and enhance flavors that we may not otherwise notice.
• Coat the tongue, giving our taste buds a longer and more intense exposure to flavors.
• Intensify flavor when aromatics are added into cooking oil, or into butter while mixing.
• Promote surface browning (which water cannot do).
• Present a new flavor from browning, such as “nuttiness, sweetness, meatiness, earthiness, or savoriness (umami)” (Nosrat, 2017).
• Lubricate pans or pots to prevent the food from sticking or overcooking.
• Add moisture to baked goods.

Healthiest Cooking Oils

The following oils contain essential vitamins and higher amounts of monounsaturated fats, a solid source of protein:

• Extra virgin olive oil (EVOO). EVOO is the least processed oil and is mechanically extracted with no change to the oil (Champion, 2024). A maintainer of vitamins, minerals, flavor, as well as natural chemicals and compounds, olive oil also has antioxidants such as vitamin E (Page & Dornenburg, 2008). Smoke point: 325–350°F; use it for sautéing or to make sauces and dressings.
• Avocado oil. With a fruity and nutty flavor, avocado oil contains antioxidants and oleic acid, a monounsaturated omega-9 fatty acid. Avocado oil aids in meal satiety. Another benefit is that pairing it with a meal increases absorption of vitamins A, D, E, and K. Smoke point: 520°F. Uses: emulsify, fry, grill, sauté, and roast. Great for any type of high-heat cooking (Page & Dornenburg, 2008).
• Almond oil. A blood sugar stabilizer, almond oil embodies nutrients like copper, magnesium, omega-3 fatty acids, and vitamin E. It also protects the nervous system from harm. Smoke point: 420°F; use it for sautéing or roasting. (The smoke point of cold-pressed or unrefined almond oil won’t be this high, though.)
• Sesame oil. With a palatable, specific smell and taste, sesame oil is frequently used in Asian dishes (Champion, 2024). Toasted sesame oil enhances the flavor even more. Flavor enhancement is the best use of this oil, adding flavor to stir-fried rice, roasted vegetables, salad dressings, and sauces. This oil also protects against neurodegenerative diseases like Parkinson’s and Alzheimer’s and promotes blood sugar management for type 2 diabetics. Smoke point: 410-450°F; use it for sautéing and roasting.
• Safflower oil. Heart-healthy safflower oil mitigates blood sugar levels. Almost tasteless, safflower oil remains a liquid even upon refrigeration. Its best uses are in cold salads, salad dressings, and for cooking in high heat. Smoke point: 440–520°F; use it for cold preparations as well as sautéing and roasting.
• Flaxseed oil. A palpable source for vegetarians due to its fatty acids, flaxseed oil also encourages lower blood pressure. Flaxseed oil is sensitive to heat, plus it spoils quickly, requiring continuous refrigeration. Because of its low smoke point, it is not suitable for cooking but may be used in salad dressings. Smoke point: 200–225°F; use it to drizzle over dishes or in a salad dressing.

Cooking Oils to Avoid

Some oils can be harmful to our health because they increase inflammation in the body. Vegetable oils are the greatest offender. The following oils are the least healthy and should be replaced if possible (Sacks et al., 2017):

• Canola oil. This oil is made from rapeseed, a seed related to the mustard plant, cabbage family, and the turnip. In early human history, it was primarily used for fuel (Falkowitz, 2024). It is produced from genetically modified crops and processed with the chemical 
• Soybean oil. Generally marketed as “vegetable oil,” soybean oil “contains unstable fats that will destroy the nutritional value of your food,” says Mehak Naeem, RDM (Gold & Leffler, 2024). Its extremely low smoke point can cause food to burn easily.
• Palm oil. This oil is often substituted for other unhealthy trans fats, but much of the fat content in palm oil is the type of saturated fat that increases bad cholesterol (Kunik & Panoff, 2023).
• Coconut oil. Used on a regular basis, coconut oil is not recommended because it is solid at room temperature. This means it has over 90 percent saturated fat, more saturated fat than lard. Adverse health effects from its use include increased LDL cholesterol (Kunik & Panoff, 2023). 
• Sunflower oil. This oil is especially high in polyunsaturated fatty acids (PUFAs). These are considered unstable when heated. Because of this, sunflower oil — and other PUFAs, such as rapeseed (canola), corn oil, and grapeseed oil — should not be used for frying, per Ellie Busby, registered nutritionist and founder of Vojo Health. She says, “Sunflower oil seems to be the worst to fry with and has higher levels of toxic compounds after frying compared to rapeseed oil” (Gold & Leffler, 2024).
• Corn oil. The corn oil name can be deceiving, as it is made from genetically modified plants instead of vegetables. Its great amount of omega-6 fatty acids can contribute to chronic inflammation and health issues like diabetes, cancer, heart disease, arthritis, and Alzheimer’s disease (Ambreen et al., 2020).

It is important to note that various sources agree on the health aspects of most of these oils. However, Champion claims that canola oil is a good oil to use, and Forrest iterates that studies do not confirm the ill health effects of coconut oil (Champion, 2024; Forrest, 2024).

References

• Ambreen, G., Siddiq, A., & Hussain, K. (2020, April 13). Association of long-term consumption of repeatedly heated mix vegetable oils in different doses and hepatic toxicity through fat accumulation. Lipids in Health and Disease, 19, 69. doi.org/10.1186/s12944-020-01256-0
• Champion, D. (2024, January 9). What are the healthiest oils to cook with? Ohio State Health & Discovery. health.osu.edu/wellness/exercise-and-nutrition/healthiest-oils-to-cook-with
• Cleveland Clinic. (2023, January 18). Choosing and using cooking oils: what to use and when. health.clevelandclinic.org/how-to-choose-and-use-healthy-cooking-oils
• Falkowitz, M. (2024). Why is it called canola oil? Taste. tastecooking.com/called-canola-oil/#:~:text=That’s%20because%20canola%20oil%20is,fuel%20rather%20than%20a%20food
• Forrest, C. (2024, January 6). What are the safest and healthiest oils for cooking? Clean Eating Kitchen. cleaneatingkitchen.com/what-are-the-safest-cooking-oils
• Gharby, S. (2022, January 11). Refining vegetable oils: Chemical and physical refining. Scientific World Journal. onlinelibrary.wiley.com/doi/10.1155/2022/6627013
• Gold, B. & Leffler, S. (2024, January 17). 7 healthiest cooking oils – and which to avoid. Real Simple. realsimple.com/health/nutrition-diet/healthiest-cooking-oil
• Kubala, J. (2024, January 9). Which cooking oils are best for your health? Health. health.com/best-and-worst-cooking-oils-8405160
• Kunik, K. & Panoff, L. (2023, October 24). 4 healthier cooking oils (and 4 to avoid). Healthline. healthline.com/nutrition/best-cooking-oils 
• La Tourangelle. (2021, July 16). What is expeller-pressed oil? latourangelle.com/blogs/general/what-is-expeller-pressed-oil 
• Marchand, V. (2010, July–August). Trans fats: What physicians should know. Paediatrics Child Health. ncbi.nlm.nih.gov/pmc/articles/PMC2921725
• National Cancer Institute. (n.d). Free radicals. cancer.gov/publications/dictionaries/cancer-terms/def/free-radical#
• Nosrat, S. (2017). Salt fat acid heat: The elements of good cooking. New York, NY: Simon & Schuster.
• Page, K. & Dornenburg, A. (2008). The flavor bible. New York, NY: Voracious/Little, Brown and Company, Hachette Book Group.
• Sacks, F., Lichtenstein, A., Wu, J., Appel, L., Creager, M., Kris-Etherton, P., Miller, M., Rimm, E., Rudel, L., Robinson, J., Stone, N., Van Horn, L., & American Heart Association. (2017, July 18). Dietary fats and cardiovascular disease: A presidential advisory from the American Heart Association. Circulation, 136(3), e1–e23. https://doi.org/10.1161/CIR.0000000000000510

Kimberly Whiteside Truitt is a former food service manager at Camp Gilmont and Camp Zephyr and has served on Camping Magazine’s Editorial Advisory Committee. Kimberly was a presenter at the 2018, 2020, and 2023 North American Food Service and Maintenance Conferences.