The risks of cooking on grills, ovens and barbecues

Throughout history, the ancestral diet has evolved to give rise to the current westernized pattern. This is characterized by a high presence of animal fats and proteins, sugars and processed foods, along with a decrease in the consumption of fresh foods, both fruits and vegetables and fish.

The data is worrying because diets high in sugar, animal products, red meat and alcohol have been linked to the development of colorectal cancer. Quite the opposite of whole grains, fruits and vegetables, which have shown a protective effect against this pathology.

Embers, smoke and toast
Regardless of nutritional characteristics, modern diets have a high presence of processed foods. These are usually rich in additives that prolong their shelf life and improve their organoleptic properties. To make matters worse, when preparing them, we often choose quick and simple culinary techniques such as grilling, barbecue, grilling or frying, which result in golden, crispy and tasty foods.

Within this context the term xenobiotic arises. This name includes all substances external to the body that we add to food during processing or cooking. Most of them are generated during high-temperature cooking and have the ability to damage our cells, increasing the risk of injury and tumor progression.

There are different types of xenobiotic compounds. Among the most important are heterocyclic amines and polycyclic aromatic hydrocarbons. They are not naturally present in foods but are mainly incorporated when we cook meats and fish at high temperatures.

They are also formed during the incomplete combustion of wood or charcoal and are deposited on top of the product, giving rise to that smoky flavor that is so popular in different populations. Hence they are present in smoked products.

Then there are nitrites and nitrates, naturally present in some foods such as vegetables, which are also often used as food additives to preserve meats, cheeses, etc. And acrylamide, which is generated in foods rich in carbohydrates that are baked, toasted or fried. For example, French fries or toast for breakfast.

Better grilled than on the barbecue
Depending on the xenobiotic compound, the recommendation of some culinary techniques over others could be considered. For example, 100 grams of a barbecued skin-on chicken thigh leads to the formation of 17 ng of a compound called PhlP, a heterocyclic amine classified as a possible carcinogen, according to the IARC (International Agency for Research on Cancer). However, the same portion cooked on the grill accounts for less than a quarter of this compound. And if we prepare it in the oven, it is drastically reduced.

Therefore, it is not only what we eat that matters but how we cook it. In general, it is advisable to avoid direct contact of the food with the heat source by reducing the brown color of the surface. As an alternative, you can use techniques in which you cook for longer but at low temperatures. At temperatures below 150 ℃, practically undetectable levels of these compounds appear.

Culinary techniques such as marinating meats or fish, marinating, the use of spices, garlic or lemon and the use of olive oil have been shown to reduce the formation of these compounds.

In the case of barbecue, the use of vertical barbecues could reduce the formation of xenobiotics by 10 to 30 times. Probably because it prevents meat and fish from absorbing the smoke produced by burning fat on charcoal. Using additives to achieve the smoked flavor is another healthier alternative.

On the other hand, the formation of nitrosamines can be minimized using reducers such as vitamin C, vitamin E and polyphenols, naturally present in fruits, vegetables and vegetable oils.

It is also recommended to avoid overbaking pastry products, as well as not exceeding 175℃ during frying in order to obtain a yellowish golden color instead of a brownish golden color to reduce the amount of acrylamide in a food.

Xenobiotics, probiotics and microbiota
As with almost everything in food, the dose makes the poison. But what dose of xenobiotics is harmful? The answer is complicated.

When evaluating the impact of these compounds on health, it must be taken into account that an individual's diet is very complex. The balance between substances with possible harmful action against our cells and beneficial substances can determine the progression of damage. On the other hand, some dietary components such as fiber can counteract the damage of xenobiotics at the intestinal level.

For example, probiotics, which we can define as live microorganisms that, when ingested in adequate quantities, exert beneficial effects on health beyond those inherent to basic nutrition. Foods containing probiotics, as well as fermented foods (with beneficial bacteria, fungi and yeast), can counteract the harmful effect of xenobiotics. Hence, it is recommended to consume dairy and vegetable products such as yogurt, cheese, kefir, kombucha or sauerkraut.

Nor should we ignore that the millions of microbes we have in our intestine, known as intestinal microbiota, can modify the ability of xenobiotics to cause harm. That is why it is important to promote a correct composition of our microbiota through diet and healthy lifestyle habits.

Source: The Conversation. Authorship: Sonia González Solares, Full Professor at the University of Oviedo. Researcher in the human microbiota diet and health group at ISPA, University of Oviedo; Clara González de los Reyes-Gavilán Research Professor at the CSIC, Institute of Dairy Products of Asturias (IPLA – CSIC)

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