Oils are essential ingredients in every kitchen, from olive oil to high-heat cooking oils, but their misuse can turn them from a healthy element to a harmful substance for the body.
Experts and specialists provide scientific information about when oil becomes toxic and how to use it safely.
Nutrition experts confirm that heating oil above the "smoke point" leads to its decomposition and the release of harmful oxidative compounds such as aldehydes and peroxides. These compounds are associated with body inflammation, oxidative stress, and may be carcinogenic in the long term.
For example, extra virgin olive oil can withstand up to ~210°C, while avocado oil can reach up to ~250°C, according to Harvard T.H. Chan School of Public Health.
Reusing oil multiple times in deep frying increases the formation of trans fats and lipid oxidation compounds, raising the risk of heart disease, liver disorders, and diabetes. Experts advise using oil only once for deep frying, according to the Food Chemistry Journal, 2018.
Studies indicate that some refined oils, especially palm or hydrogenated oil, contain high levels of saturated and trans fats even before heating, which may harm the liver and increase the risk of chronic diseases, as explained in the WHO Report on Trans Fats, 2021.
Experts recommend using oil safely by choosing the right oil and using it at a low temperature such as extra virgin olive oil.
Other oils that can withstand higher temperatures include refined canola oil, avocado oil, or ghee (Ghee).
Reusing should be avoided as used oil decomposes and becomes harmful, and proper storage of oil in a dark and cool place away from light and heat is essential. Avoid heavily processed oils, read labels, and steer clear of hydrogenated oils or synthetic palm oil.
Therefore, oil becomes toxic when it exceeds the smoke point, is reused, or is overly processed. Opting for natural unsaturated oils like olive oil, avocado, and nut oils is the safest choice for heart health and overall body wellbeing.
