When cooking oil is exposed to high cooking temperatures, oxygen in the air will combine with the oil's unsaturated fat resulting in free radicals - our health enemy. When we eat fried food containing free radicals, our body will be affected and develop various chronic illnesses such as cardiovascular diseases, paralyzes, hypertension, arthritis, allergies, hypersensitive immune system, immune system weakening, cataract, wrinkles, and cancer.

One of the most popular frying dishes in Thailand is Chinese donuts. Vendors often use a large amount of cooking oil to fry the donuts in one time. Thus, they tend to reuse the same cooking oil several times in order not to waste the oil. When the level of cooking oil is reduced, they just pour down new cooking oil without rinsing the old one.

Free radicals increase according to the frequencies of the cooking oil being used. If fried food is produced in factories, there will be a measure to prevent using cooking oil for so many times that can cause health risks. In European Union, there is a law prohibiting the usage of cooking oil in cooking process after the oil is dump by food factories. This type of oil can't even be mixed in animal food. The only way it can be used is to produce soaps, shampoos, or lipsticks.

In Thailand, however, there is no measure to control cooking oil reuse in the cooking process such as in Chinese donuts, fried bananas, deep fried minced fish, etc. Vendors usually cook this type of food using the same cooking oil over and over again. In some cases, some people may have acute oral lesions when eating Chinese donuts.

Acute oral lesions happen because free radicals in Chinese donuts cause wounds in the soft tissue of the neck and when viruses or bacteria penetrate through these wounds, neck infections and sore throat will inevitably occur.

Besides risks from free radicals, oxidation occurring when frying food can also cause:

- Useful free radicals such as vitamin E in the oil or beta-carotene from the food.

- A large amount of free radicals. The first group is called Trans which is not dangerous to our health. The second group is Polymer occurring from unnatural disintegration. If our body receives Polymer for 20-30 years, our cells will be weaken and we can have heart disease, paralyze, arthritis, allergies, hypersensitive immune system, cancer, etc.

- High cooking temperatures for 200-300 Celsius will transform protein into Acrolein, a substance that can cause cancer. This substance can destroy the structure of flour and sugar. Some flour can be changed into a cancer risk substance. Such flour is flour from potato which is being fried in high temperatures. How to reduce risks from fried and stir-fried food

Don't pour cooking oil into a hot pan and heat the oil until white smoke appears. The white smoke is free radicals which will be our health risk. It is better to use traditional Chinese cooking style. That is to add a little bit of water into the pan, wait until the water is hot then takes the water out. Add cooking oil into the pan and start frying the food. While cooking, you can add cooking stock in it to increase flavor, help reducing the temperature to 100 Celcius which is a non- dangerous degree, prevent the food from burning and preserve its taste and nutrition. Thus, this way of cooking is safer and preserves higher nutrition than other ways.

Another way of cooking is to cook in an old European style. That is to firstly put vegetables into the pan and add cooking oil later.

Anti-free radicals substances that can reduce cooking oil danger are such as high sulpher food like garlic and onion. In Thailand, we have been told to add smashed garlics before frying food. Garlic's smell can add taste to food and also prevent free radicals from harming us.

There are two types of good cooking oil. The first one is oil with high saturated fat like lard, coconut oil, and palm oil. The second one is monounsaturated fat in olive and peanut oil.

There is an advantage and disadvantage of both types of cooking oil. High saturated fat oil like lard is safer when cooking because it doesn't have double bond that will create oxidation so it provides less cancer risk and can prevent deterioration of our body. However, this type of oil can cause high blood cholesterol if using in a large amount. For monounsaturated fat oil, it can cause less free radicals or cancer risk; yet, it is rare and expensive like olive oil.

The oil which doesn't cause much high blood cholesterol and free radicals is such as high oleic sunflower, which is not a typical kind of sunflower oil that is widely sold, and peanut oil which is rarely found in Thailand.

When frying food, use only adequate amount of oil or as less as possible. After finish frying food, always throw away the used oil. Don't reuse the oil for it will be dangerous for your health and cause chronic diseases. It doesn't worth it if you save your money in buying cooking oil but you have to pay a lot more for medical bills.

Thais' favorite fried food such as Chinese donuts, fried bananas, deep fried minced fish, deep fried minced pork or crab, fried fish, and fried chicken from famous franchised restaurants are being cooked in reuse oil. This type of food is full of free radicals which are harmful to our body.

The other ways of cooking are, such as boiling or steaming. For in stance, if you want to eat fish, you should steam, grill or boil it without frying. You can do the same with vegetables by blanching, and steaming instead of frying.