The two main types of dietary fat are:
- saturated fat (mostly from animal sources; hard at room temperature)
- unsaturated fat (mostly from plant and fish sources; oil at room temperature).
The Dietary Guidelines for Americans recommend we limit the hard saturated fats as are they associated with heart disease. Unsaturated fats, which include mono- and polyunsaturated fats, are considered beneficial because they can help lower the “bad” LDL cholesterol and therefore reduce the risk of heart disease.
When it comes to consuming unsaturated fats, the Dietary Guidelines for Americans recommends we consume plant oils, such as canola, corn, olive, peanut, safflower, soybean, and sunflower. Other plant-sources of oils include nuts, seeds, olives, and avocados. Fish and other seafood are important for omega-3 oils.
What About Canola Oil?
Canola oil, derived from the rapeseed plant, is a plant-based oil with a favorable nutrition profile. It has the least amount of saturated fat (7%) compared to other oils (including olive) and the most omega-3 fatty acids (19%). It is also a good source of vitamins E and K. It has a neutral flavor that is ideal when baking, as well as for sautéing, stir-frying, or grilling.
Smoke Point
An oil’s smoke point (burning point) depends on the type of oil and its chemical composition. Some oils such as extra virgin olive oil and coconut oil have low smoke points ranging from 325-375°F while the smoke point of oils such as canola, peanut, and corn oil range from 400-450°F. No matter what oil you choose to cook with, you want to avoid overheating and burning it to retain the best taste and to avoid damaging the heart healthy fatty acids contained in the oil.
You might have heard that when oils are heated, they release harmful toxins and trigger inflammation. While studies show that oils release harmful by-products when heated for long amounts of time at extremely high temperatures, this is not representative of normal kitchen cooking practices. Moreover, the link between possible unhealthy compounds and effects on health is largely dependent on dose. For instance, recipes typically call for 2 tablespoons or less of oil when sautéing, which is an extremely small dose when split among 4-6 servings.
In a study published in The American Journal of Clinical Nutrition, researchers assessed the association between consumption of partially hydrogenated vegetable oils (partially “hardened” and containing higher saturated fat), natural vegetable oils, and inflammatory markers in the blood among women. They found that higher intakes of natural vegetable oils—canola oil, corn oil, sunflower oil, soybean oil, and olive oil—were associated with lower concentrations of inflammatory biomarkers, whereas the processed fats (soft or hard margarines and shortening) were associated with higher concentrations of these biomarkers.
In addition, the Journal of the Academy of Nutrition and Dietetics published a systematic review of 15 randomized controlled trials (regarded as the gold standard for scientific evidence) which assessed the effect of dietary linoleic acid (a type of polyunsaturated fat common in vegetable oils) on inflammation in healthy individuals. Virtually no evidence showed that adding linoleic-rich vegetable oils to the diet increase the concentration of inflammatory markers. Oils that are highest in linoleic acid (aka polyunsaturated fat) include canola, peanut, soybean, grapeseed, and sunflower oil. You might be surprised to learn that canola oil contains more polyunsaturated fat than olive oil (4 grams in 1 tbsp of canola oil versus 1.5 grams in 1 tbsp of olive oil). Both are great choices and serve an important role in a healthy diet.
The Bottom Line
Dietary fat can be a positive part of a well-balanced and health-promoting diet. Insufficient evidence supports the claim that plant oils cause inflammation. That said, you do want to focus your attention on unsaturated fat from olive, peanut, and canola oils, as well as avocado, nuts, seeds, and fish. These health-promoting fats help increase satiety, lower cholesterol levels, and support heart health.
When it comes to the confusion around canola oil, rest assured it is safe, health-promoting, and non-inflammatory. Just like in all aspects of the diet, you want to have variety in the types of oils you use to cook and the types of fat sources you consume. Instead of obsessing over the exact breakdown of the poly-, monounsaturated, and saturated fat contents of the oil, try thinking of its flavor profile when determining which one to use. For example, the neutral flavor of canola oil is often the preferred choice when baking. A peanut or sesame oil is tasty if you are making a stir-fry, as is olive oil in a Mediterranean inspired dish. The bottom line is that when it comes to fat, try your best to keep it plant-sourced!
References
2015-2020 Dietary Guidelines for Americans
Dietary fats. (n.d.). www.Heart.Org. https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/fats/dietary-fats
Edelstein, Sari. (2018). Food Science: An Ecological Approach: Vol. Second edition. Jones & Bartlett Learning.
Esmaillzadeh, A., & Azadbakht, L. (2008). Home use of vegetable oils, markers of systemic inflammation, and endothelial dysfunction among women. The American Journal of Clinical Nutrition, 88(4), 913–921.
Guillaume C., et al. “Evaluation of Chemical and Physical Changes in Different Commercial Oils during Heating”. Acta Scientific Nutritional Health 2.6 (2018): 02-11.
Johnson, G. H., & Fritsche, K. (2012). Effect of Dietary linoleic acid on markers of inflammation in Healthy Persons: A Systematic Review of Randomized Controlled Rrials. Journal of the Academy of Nutrition and Dietetics, 112(7), 1029-1041.e15.
U.S. Canola Association. Retrieved April 15, 2021, from https://www.uscanola.com/
Written by guest blogger Emily Stewart, nutrition student at Simmons University and aspiring sports dietitian.