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The Health Impact of Cooking Oils: A Comparison

When it comes to selecting which oil you're going to use for your cooking project, it turns out that flavor is only one of many considerations. Here's everything you need to know about the health impact of various cooking oils...

All cooking oils are 100% fat, but the type of fat varies. Oils contain different ranges of saturated, polyunsaturated, and monounsaturated fats.

Saturated fat is more solid at room temperature and is known to contribute to increased risk of heart disease. Oils high in saturated fat include butter, ghee, lard, tallow, palm tree, palm kernel, cottonseed and coconut. 

Trans fats are created through hydrogenation, a process that takes oil that was liquid at room temperature (unsaturated) and turns it into solid fat (saturated). For example, liquid vegetable oil contains no trans fats, but when it’s hydrogenated into solid vegetable shortening, trans fats are created.

Heating oil to high temperatures over a longer period of time, such as deep-frying foods in commercial kitchens, also creates trans fatty acids.

Trans fats are bad news for our health because they increase cholesterol levels, create inflammation that is associated with stroke, diabetes, and heart disease; and contribute to insulin resistance and diabetes. According to Harvard Health Publishing, for every 2% of calories from trans fat consumed daily, the risk of heart disease rises by 23%. The current recommendation is to completely avoid trans fats in foods. 

Polyunsaturated fats are considered essential fats because they're required for normal body functions, but since your body can't make them, we have to get them from our foods. There are two main types of polyunsaturated fats: omega-3 fatty acids and omega-6 fatty acids. 

Omega-3 fatty acids help form the structure of cell membranes and are found in higher concentrations in the eye, brain and sperm. They also play important roles in cardiovascular health. Good sources of omega-3 fatty acids include fatty fish such as salmon, mackerel, and sardines, flaxseeds, walnuts, canola oil, and un-hydrogenated soybean oil.

Omega-6 fatty acids help decrease inflammation and are important in blood clotting. Foods rich in linoleic acid and other omega-6 fatty acids include vegetable oils such as safflower, soybean, sunflower, walnut, and corn oils.

Monounsaturated fats can help reduce risk of cardiovascular disease and also contribute vitamin E to our diets. Good sources of monounsaturated fats are olive oil, peanut oil, canola oil, avocados, and most nuts, as well as high-oleic safflower and sunflower oils.

The American Heart Association recommends choosing oils with <4gm saturated fat per tablespoon and no hydrogenated or trans fats, choosing polyunsaturated and monounsaturated oils the majority of the time to promote health.

So, when you next shop for cooking oil...

  • Choose oils that are higher in monounsaturated or polyunsaturated fat with very low amounts of saturated fat for the healthiest oils: olive, canola, safflower, soybean, sunflower, walnut, and avocado.

  • Avoid using plant oils that are high in saturated fat. These are usually solid at room temperature due to the high percentage of saturated fat. Coconut, palm tree, palm kernel and cottonseed oils are at least 50% saturated fats.

  • Substitute a plant-based oil for animal oil whenever possible for a healthier fat profile.

  • When frying or using a wok at high heat, choose an oil with a high smoke point:  avocado, safflower, soybean, peanut, corn, sunflower.

  • Use the least amount of any oil that you can. All oil contains about 40 calories per teaspoon and those calories add up quickly.

By Lynn Grieger, RDN, CDCES

For more information about cooking oils, visit the post Cooking Oil Smoke Point Chart and/or Cooking Oils 101.

References:

  1. American Heart Association. Healthy Cooking Oils. https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/fats/healthy-cooking-oils  last reviewed 4-24-18; accessed 10-29-22

  2. University of Rochester Medical Center. Cooking Oils: Which one when and why? https://www.urmc.rochester.edu/news/publications/health-matters/cooking-oils-which-one-when-and-why posted 6-15-15; accessed 10-29-22

  3. Harvard Health Publishing. Harvard Medical School. The Truth About Fats: The Good, Bad, and In-between. https://www.health.harvard.edu/staying-healthy/the-truth-about-fats-bad-and-good  published 4-12-22; accessed 10-29-22

  4. Bhat S, Maganja D, Huang L, Wu JHY, Marklund M. Influence of Heating during Cooking on Trans Fatty Acid Content of Edible Oils: A Systematic Review and Meta-Analysis. Nutrients. 2022 Apr 2;14(7):1489. doi: 10.3390/nu14071489. PMID: 35406103; PMCID: PMC9002916.

  5. National Institutes of Health. Office of Dietary Supplements. Omega-3 Fatty Acids Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/Omega3FattyAcids-HealthProfessional/ updated 7-18-22; accessed 10-29-22

  6. American Heart Association. Monounsaturated Fat. https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/fats/monounsaturated-fats  last reviewed 6-1-15; accessed 10-29-22

  7. MasterClass. Cooking Oils and Smoke Points: What to Know and How to Choose the Right Cooking Oil

  8. https://www.masterclass.com/articles/cooking-oils-and-smoke-points-what-to-know-and-how-to-choose last updated 8-4-21; accessed 10-29-22.

  9. Spectrum. 1-2-3 Cooking; Using the Right Oil for the Right Reasons. https://welllifefm.com/wp-content/uploads/2017/04/oil_kitchen_guide.pdf  accessed 10-29-22

  10. Food Business News. Oil prices doubling, or even tripling, makes fry life a priority. https://www.foodbusinessnews.net/articles/18707-oil-prices-doubling-or-even-tripling-makes-fry-life-a-priority published 6-10-21; accessed 10-30-22.

  11. USDA Economic Research Service. Summary Findings Food Price Outlook 2022 and 2023. https://www.ers.usda.gov/data-products/food-price-outlook/summary-findings/  last updated 10-25-22; accessed 10-30-22.

  12. Heart-Healthy Oils: They're Not All Created Equal. Judith C. Thalheimer, RD, LDN. Today's Dietitian. Vol. 17 No. 2 P. 24. February 2015.

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