For decades, both government bodies and the food industry have promoted the replacement of traditional animal fats with vegetable fats, propagating the idea that they are healthier. Margarines and vegetable butters have emerged en masse as beneficial alternatives for cardiovascular health. However, recent studies point to an alarming reality: the consumption of highly refined vegetable oils can be a silent killer in the long term. Although they may reduce total cholesterol, these oils are associated with an increase in mortality of up to 20 per cent.
Vegetable oils, especially seed oils, have become ubiquitous in food production due to their low cost. In Portugal, almost all processed and tinned foods contain sunflower, soya or canola oils. In supermarkets, it’s hard to find biscuits that don’t include some kind of seed oil. Restaurants and home recipes often replace olive oil with these cheaper, odourless options.
What is the real danger of seed oils?
These oils contain a high percentage of polyunsaturated fatty acids (PUFA). PUFAs are unstable and break down quickly when exposed to chemical stress. The process of refining and extraction at high temperatures increases the formation of toxic components. While saturated fats are stable under heat, unsaturated fats are prone to oxidation, promoting inflammation and the growth of cancer cells. Linoleic acid, present in abundance in vegetable oils, oxidises easily, both during refining and on supermarket shelves.
Martin Grootvelt, a food health expert, warns that meals fried in vegetable oils can contain 100 to 200 times more aldehydes than the safe daily limit set by the World Health Organisation (WHO). Aldehydes are harmful chemical compounds produced during the oxidation of oils, associated with cell damage and an increased risk of cancer.
The Balance of Omegas
In addition to toxicity, there is the issue of the imbalance between omega-6 and omega-3 in the modern diet. Excessive consumption of omega-6, present in processed foods, to the detriment of omega-3, can promote inflammation, favouring the growth and spread of cancer cells. On the other hand, omega-3 fatty acids have been shown to reduce inflammation, control cancer growth, improve the effects of certain cancer treatments and reduce the risk of cachexia in cancer patients.
To protect your health, avoid refined vegetable oils, especially those rich in linoleic acid. Opt for healthier fats, such as extra virgin olive oil, which is rich in oleic acid and less prone to oxidation. If you need to fry food at high temperatures, choose saturated fats such as traditional butter or coconut oil. Remember that the food industry often prioritises quantity over quality. Making conscious food choices can have a significant impact on your long-term health.
