The toxic truth about vegetable oil

When I go to my local curry restaurant, I always ask the waiter to make sure my chicken jalfrezi, spinach curry and lentil daal is cooked in ghee, not vegetable oil. They know me now so I don’t get rolling eyes and shrugs anymore. It helps that I leave a generous tip. But it’s worth it. As a cardiologist with an interest in obesity and heart health, there is no way I am going to put my health at risk by eating poisonous compounds that are created when vegetable oils are cooked at high heat. Unfortunately, curry lovers in the UK, and the vast majority of Indians on the subcontinent are doing just that – they have abandoned traditional ghee (a kind of clarified butter) in favour of ‘healthier’ vegetable oils. The outcome of this trend has been disastrous – driving higher rates of heart disease, type 2 diabetes and cancer.

Studies now show that sunflower oil, corn oil and other vegetable oils are unstable at high temperature and quickly break down into toxic aldehyde which is linked to an increased risk of developing getting cancer among other things. A recent study showed that cooking in vegetable oil for just 20 minutes, produced 20 times the permitted levels of aldehyde recommended as a maximum limit by the World Health Organisation. When I see someone who is otherwise healthy frying healthy kale and tofu in sunflower oil, I despair how good intentions can go so wrong.

For years, we have thought that vegetable oils, including sunflower oil and corn oil, were better than butter and animal based fats. But the tide of opinion has changed and the latest scientific evidence reveals that dairy products actually protect against heart disease and type 2 diabetes. Sadly, the news has come too late for the millions of people who now shun full-fat milk and butter because they think it is bad for them.

I now always advise my patients to actively avoid eating any industrial vegetable oils. Cold pressed extra virgin olive oil, however, will protect your heart and give you a bit of a boost when it comes to antioxidants which help to mop up damaging free radicals in the blood. But the vast majority of vegetable oils are not going to help, despite claims that they help reduce cholesterol. A recent BMJ analysis found that even if cholesterol levels do decline on a diet of vegetable oil margarines, there is no knock-on benefit to heart health and a more worrying trend to increasing the risk of death.

So my message is drizzle your cold pressed olive oil on your chorizo to your (healthy) heart’s content but stick to butter (and ghee) when you want to create a bit of a sizzle.

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Dr Aseem Malhotra

Dr Aseem Malhotra is a Consultant cardiologist who is a leading campaigner highlighting the harms of diet related disease and a vocal advocate for greater transparency in medicine. He is an adviser to the National Obesity Forum and a member of the board of trustees of health think tank, The King's Fund. This year he was named in the Debretts 500 in a list of 19 of the most influential people in science and medicine in Britain.

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