How Vegetable Cooking Oils Destroy Your Health

You thought sugar was bad? Meet its evil twin

Maria Cross


Image: author’s

I recently came across these empty cooking oil containers that had been deposited behind a restaurant near my home. It’s not an unusual sight in areas with catering establishments. Less visible is the damage that these commonplace oils do to human health.

You don’t have to search the streets to find variations on this theme. Odds are that corn, soya, and sunflower seed oils are your store cupboard staples, and they have never come under scrutiny. Why would they? They contain polyunsaturated fats, which, you are led to believe, are good for you.

Don’t be led: the truth is that by the time they have been bottled and put on the shelf, these polyunsaturated oils have been processed beyond recognition. Any goodness they may once have contained has been well and truly dispatched.

It’s time to shed some light on these ultra-processed products masquerading as healthy options.

Chemical carnage

Cooking oils are usually extracted from beans (soya), grains (corn) or seeds (typically sunflower, sesame, or safflower). The most common extraction method involves a solvent called hexane, derived from petroleum.

This procedure is followed by a series of refining processes, including degumming, bleaching and deodorization. These processes are performed at temperatures in excess of 200ºC.

During this refinement process most of the nutrients are destroyed, including vitamin E — which is present naturally in the oil as a protective antioxidant. The high temperatures involved during refinement create rancid odours that must be neutralised, hence the deodorization process.

But nutrient loss is the least of your problems. The most disturbing aspect of all this activity is the generation of high levels of free radicals, trans fatty acids, and chemicals called aldehydes.

Free radicals are unstable molecules that create a good deal of damage in the body, and in excess are associated with cardiovascular disease, cancer, dementia, and premature ageing. Polyunsaturated fats — the kind found predominantly in vegetable cooking oils — are highly vulnerable to free…



Maria Cross

MSc. Registered nutritionist, specialising in gut and mental health. OUT NOW! My new book, How to Feed Your Brain. mariacrossnutrition @mariacross