Has someone ever told you not to heat olive oil? Was the reason that they feared olive oil would suddenly transform into saturated or trans-fatty oil? Well, let’s break this down once and for all!
Some say that dangerous trans-fats can form when olive oil is heated but the fact is that this process, called hydrogenation, can take several hours. You cannot make a saturated product like margarine at home by heating olive oil or any other vegetable oil in a pan. You would need to bubble hydrogen gas in high heat in the presence of a metal catalyst (palladium / nickel) Conditions which simply don’t exist in your kitchen.
The Downside With Heating Olive Oil
There is actually a downside when frying with olive oil – heating olive oil will evaporate the alcohols and esters which make up its delicate taste and fragrance. It will therefore lose its’ flavor.
Is it Toxic?
Vegetable oils can, however oxidize as they are exposed to air, light or heat and some of these products are known to be toxic BUT they are formed in minimal amounts and are easily dealt with by our bodies. Corn oil and sunflower oil oxidize easier while olive oil and coconut oil are more resistant to oxidation. Extra Virgin olive oil even contains antioxidants to minimize oxidation. Smoke from heated oils can, however, contain toxic polycyclic aromatic hydrocarbons (PAHs) and this should be avoided (The smoke point of olive oil is around 200°C).
To conclude, there is no current evidence that frying with olive oil should increase your risk of cardiovascular disease!
1. How heating affects extra virgin olive oil quality indexes and chemical composition,” Y. Allouche, A. Jiménez, J. J. Gaforio, M. Uceda, G. Beltrán, J Agric Food Chem, 2007 Nov 14;55(23):9646-54. Epub 2007 Oct 13, PMID: 17935291
2. Bente Lise Halvorsen. Determination of lipid oxidation products in vegetable oils and marine omega-3 supplements. Food Nutr Res. 2011; 55: 10.3402/fnr.v55i0.5792.
3. Baynes JW. Dietary ALEs are a risk to human health–NOT! Mol Nutr Food Res. 2007 Sep;51(9):1102-6.
4. Song J. Analysis of Trans Fat in Edible Oils with Cooking Process. Toxicol Res. 2015 Sep;31(3)
5. Sayon-Orea C. Does cooking with vegetable oils increase the risk of chronic diseases?: a systematic review. Br J Nutr. 2015 Apr;113 Suppl 2:S36-48.
6. Yao Z. Characteristics of PAHs from deep-frying and frying cooking fumes. Environ Sci Pollut Res Int. 2015 Jun 12.