Recently has been recommended that using vegetable oils to fry food may be bad for your health, as a result of the production of toxic chemicals known as aldehydes during the heating process.
Aldehydes are basic organic structures – compounds which hold a carbon-oxygen double bond – and are plentiful in nature.
Aldehydes are formed in the human body in minor amounts as by-products of usual fructose and alcohol metabolism. Furthermore, consumption of dietary aldehydes is thought to contribute to human diseases including diabetes and heart disease.
So you may be asking, what about about Olive Oil? Is it classed as a vegetable oil, and is it safe to fry food with it?
Olive Oil consumption is always linked to exceptional health, and forms a main component of the Mediterranean diet.
The Mediterranean diet is known to reduce the risk of disease and early death. Olive Oil, produced by pressing olives, is commonly used throughout the globe in food preparation, whether for frying, drizzling or as a part of a salad dressing.
As a result, it is classed as a vegetable oil, as it is produced from vegetable matter, as opposed to animal fats such as lard or goose fat.
Of the vegetable oils that have been tested for heating-induced aldehyde content, Olive Oil actually performs quite well. Researchers from the University of the Basque Country analysed olive, sunflower and flaxseed oils for their aldehyde content after the oils had been heated to 190℃.
They then discovered that heating the polyunsaturated sunflower and flaxseed oils created greater quantities of aldehydes almost instantly, whereas heating monounsaturated Olive Oil created smaller aldehydes and much later in the heating process.
This is thought to be a result of the structural difference, with polyunsaturated oils containing more regions ripe for chemical reaction.
A very small amount is known about what constitutes a low or high dose of aldehydes in food in humans. If olive oil is used to shallow fry foods for short periods, it is unlikely that your body would be exposed to greater concentrations of aldehydes than it generally would as a result of your body’s normal metabolic processes, mentioned earlier.
While there are other healthier ways to cook foods, frying food with Olive Oil is unlikely to be significantly bad for your health.
Heat causes chemical changes in all oils and this alters their aroma, flavour and nutritional content. Overheating oil during cooking will typically result in a dirty smoky kitchen, poor tasting food and the creation of harmful chemicals.
Olive Oil is no different from other oils. If you burn it (heat it above its smoke point) it will taste bad and it will contain harmful chemicals. Smoke points usually tend to increase with Olive Oil quality, as the free fatty acid content tends to decrease and the antioxidant content increases.
When cooking with Olive Oil, any potential harms can be lowered by using high quality oil and making sure you keep the oil below its smoke point; it will also make your food taste nicer.
Ultimately, frying in general is not the healthiest way to prepare food, but if you are going to fry then frying in Olive Oil is not a bad decision.