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   Jun 29

It IS safe to eat food fried in olive oil: Scientists put an end to confusion as they conclude it is the best choice

Frying any vegetable oil causes the release of toxic chemicals caused aldehydes

Dietary aldehydes is thought to contribute to human diseases, such as diabetes

Olive oil has been shown to produce less aldehydes and later on in cooking

Good-quality olive oil may be less harmful due to its higher smoking point

Frying is not the healthiest way to prepare food, but olive oil is not a bad choice

‘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 choice,’ according to Rachel Adams, senior lecturer in biomedical sciences at Cardiff Metropolitan University.

The release of toxic chemicals when heating olive oil has long been a cause for health concerns, with previous studies even linking them to cancer and diabetes.

Yet experts writing in The Conversation argue the risk depends on the quality of the oil and the extent to which you heat it.

Although one expert adds that frying in general is not the healthiest way to cook, she maintains that olive oil’s antioxidant-rich content makes it the best choice.

The risk of heating olive oil depends on its quality and the extent to which you cook it


A key nutrient in olive oil may help to prevent cancer developing in the brain, research revealed earlier this month.

The staple Mediterranean ingredient contains a compound called oleic acid that stops cancer-causing genes from functioning in brain cells, the study found.

It is unclear whether increasing our consumption of olive oil may prevent brain cancer, however, the study’s findings could lead to new disease therapies, the researchers said.

Study author Dr Gracjan Michlewski, from the University of Edinburgh, said: ‘While we cannot yet say that olive oil in the diet helps prevent brain cancer, our findings do suggest that oleic acid can support the production of tumour-suppressing molecules in cells grown in the lab.

‘Further studies could help determine the role that olive oil might have in brain health.’

How healthy is olive oil?

It recently has been suggested that using vegetable oils to fry food may be bad for your health due to the production of toxic chemicals called aldehydes during the heating process.

Aldehydes are simple organic structures – compounds which contain a carbon-oxygen double bond – and are abundant in nature.

They are formed in the human body in small amounts as by-products of normal fructose and alcohol metabolism.

Consumption of dietary aldehydes is thought to contribute to human diseases including diabetes and heart disease.

But what about olive oil? Is it classed as a vegetable oil, and is it safe to fry food with it?

Around half of UK households now use olive oil, which demonstrates a sizeable shift in our oil use in recent years, according to James Brown, Aston University and Rachel Adams, Cardiff Metropolitan University.

This may be in part because olive oil consumption is frequently linked to good health, and forms a central component of the Mediterranean diet. The Mediterranean diet is itself known to reduce the risk of disease and early death.

Olive oil, produced by pressing olives, is commonly used across the world in food preparation, whether for frying, drizzling or as a part of a salad dressing. It is therefore classed as a vegetable oil, as it is produced from vegetable matter, as opposed to animal fats such as lard or goose fat.

Frying in general is not the healthiest way to cook, but olive oil is the best choice


Extra-virgin olive oil preserves memory and protects the brain against dementia, according to research released earlier this month.

The oil is a key ingredient of the Mediterranean diet, which is associated with a variety of health benefits, including a lower dementia risk.

Now scientists from Temple University in Pennsylvania have discovered that olive oil reduces the risk of dementia by prompting the brain to clear out harmful debris.

Regularly eating olive oil can protect your memory and your ability to learn new things as you age, according to the new study.

The discovery has been hailed as an ‘exciting’ breakthrough in the battle against Alzheimer’s disease.

How does it compare to other oils?

Of the vegetable oils that have been tested for heating-induced aldehyde content, olive oil actually performs reasonably 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 found that heating the polyunsaturated sunflower and flaxseed oils produced greater quantities of aldehydes more quickly, whereas heating monounsaturated olive oil created fewer aldehydes and much later in the heating process.

This is thought to be because of a structural difference, with polyunsaturated oils containing more regions ripe for chemical reaction.

Experiments performed for BBC’s Trust Me I’m a Doctor confirmed this, suggesting that heating olive oil, butter and goose fat produced similarly lower levels of aldehydes. These experiments collectively suggest that if you are going to fry, choosing olive oil is one of the better options.

Importantly, very little is known about what constitutes a low or high dose of aldehydes in food in humans. There is some data from animal studies, but the conclusions we can draw from them are limited.

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 normally would as a result of your body’s normal metabolic processes, mentioned earlier.

While there are clearly healthier ways to cook foods, frying food with olive oil is unlikely to be significantly bad for your health.

Should we cook with any oil?

Heat causes chemical changes in all oils and this alters their aroma, flavour and nutritional content, according to Rachel Adams, senior lecturer at Cardiff Metropolitan University.

Overheating oil during cooking will 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 tend to increase with olive oil quality, as the free fatty acid content tends to decrease and the antioxidant content increases.

The high antioxidant content of olive oil could even reduce the amount of harmful chemicals produced during cooking.

When cooking with olive oil, any potential harms can be reduced by using high quality oil and making sure you keep the oil below its smoke point; it will also make your food taste nicer.

So I agree with the author: 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 choice, Ms Adams added. If cooking with olive oil was that bad for you there would be population-based evidence to support the argument.

Source: Daily Mail

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