24 April 2019
The deep-frying process of cooking food produces chemicals that are hazardous to health. Photo: Internet
The deep-frying process of cooking food produces chemicals that are hazardous to health. Photo: Internet

Beware of cancer-causing cooking methods

The International Agency for Research on Cancer (IARC) has come up with a list of combustion-related carcinogens, including tobacco smoke, second-hand tobacco smoke, diesel and gasoline engine exhaust emissions, emissions from indoor household combustion, emissions from high-temperature frying and welding fumes.

In traditional Chinese medicine, these cancer-causing substances could be described as “toxic heat” or “fire toxins”.

Charred food, fumes from incense burning as well as second- and third-hand tobacco smoke could be more dangerous than emissions from industrial plants because we have easy and prolonged exposure to these carcinogens at home and on the streets.

For example, many people are unaware of the dangers posed by burnt or charred food.

Whether meat or vegetable, food that is overly baked, grilled, pan-fried or deep-fried could turn carcinogenic. The more burnt, the more toxic food could become.

Charred food produces toxic heat, according to traditional Chinese medicine. Its consumption results in excessive heat accumulated in the body in short run or, worse, triggers mutations and cancers in the long run.

Scientific studies also confirm that meat cooked through high-temperature methods – pan- or deep-frying, or grilling directly over an open flame – produces mutagenic chemicals such as heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs), while acrylamide is produced when high-starch food is roasted, fried or grilled for too long at high temperatures.

High temperature alone would not result in the formation of carcinogens. But when the moisture content of food is greatly reduced and the cooking temperature is higher than 120 degrees Celsius, food browning occurs.

This releases products in gases, liquids and solids that could all be cancer-inducing.

As such, gases released by grilling, baking and pan- or deep-frying, as well as burnt food should all be avoided, as they are as bad as inhaling second- or third-hand tobacco smoke.

I would therefore suggest that people avoid such cooking methods as baking, pan- or deep-frying, and grilling.

Food that is burnt or that turns brown or black must be discarded.

Another common carcinogenic source, especially in Chinese households, is incense burning, which is a form of indoor combustion.

Burning of incense releases benzene, toluene and PAHs. Studies conducted in Hong Kong and elsewhere find links between incense burning and cancers of the upper respiratory tract.

While most people know that second- or third-hand tobacco smoke is bad for the health, not too many realize that smoke from incense burning has a similar impact as a carcinogenic source.

To avoid all these “toxic heat” or “fire toxins”, the best strategy is to avoid producing them. The second best strategy is to avoid eating them or having contact with them.

Some people have the mistaken belief that they could “neutralize” the bad effects of consuming barbecued food by eating vegetables and drinking herbal tea. It doesn’t work that way.

This article appeared in the Hong Kong Economic Journal on April 5

Translation by John Chui

[Chinese version 中文版]

– Contact us at [email protected]


Registered Chinese medicine practitioner and senior lecturer of the Department of Applied Science at the Hong Kong Institute of Vocational Education (Chai Wan)

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