[Fat Bear Science] Take you to count the carcinogens hidden around you in life

Fat Bear: Grandma, haven't you finished the nuts I bought for you last time? (Grabs a nut and puts it in his mouth)

Granny Bear: Why are you in such a hurry? You should enjoy the delicious food slowly.

Fat Bear: Ugh! So bitter~ Grandma, I guess the nuts are moldy, I'll throw them away

Granny Bear: You dead baby, why are you shaking it? What a pity, only yours is rotten, the others are not rotten

In fact, similar conversations often occur in life, about leftovers, moldy peanuts...

Fat Bear has to step out today to give you some knowledge about the carcinogenicity of some foods and remind you not to do things that are harmful to your health for the sake of saving money. This is completely different from saving or not.

Ji Xiaohui

Chongqing Cancer Hospital/Affiliated Cancer Hospital of Chongqing University

Master of Oncology Attending Physician

Member of the Tumor and Cardiology Committee of Chongqing Anti-Cancer Association

I have been engaged in clinical work in tumors for nearly 5 years, mainly engaged in the medical treatment and scientific research of colorectal cancer, lung cancer and other tumors.

The onset of cancer is the result of the combined effects of genetic and environmental factors. Genetic factors are beyond our control, while the external environment, especially carcinogens in our diet, is a very important factor in the current increase in cancer incidence.

If we have a full understanding of carcinogens, many cancers can be avoided.

At present, the International Agency for Research on Cancer has classified carcinogens into five categories, namely, 1, 2A, 2B, 3, and 4, according to their risk of causing cancer to humans. Among them, Category 1 carcinogens are also called "set in stone" by some people, that is, there is sufficient evidence to prove that they are carcinogenic to humans and are clear human carcinogens. The several carcinogens we are talking about today are foods containing Category 1 carcinogens.

01

Aflatoxin: Even boiling water can’t kill me

Aflatoxin is also the most carcinogenic substance and is one of the strongest known carcinogens. It can induce liver cancer, stomach cancer, kidney cancer, lacrimal gland cancer, rectal cancer, breast cancer, ovarian cancer, small intestine cancer, etc. A single milligram per kilogram is extremely toxic, which is equivalent to the amount of a sesame seed in a ton of grain.

They exist in soil, animals, plants, and various nuts, and are especially likely to contaminate grain and oil products such as peanuts, corn, rice, soybeans, and wheat. They are the most toxic type of mycotoxins and pose a particularly prominent threat to human health.

peanut

Yellow mold often hides in moldy foods, especially foods with high starch content, such as peanuts, corn, etc.

Aflatoxin spreads in the form of spores, and food is easily implicated in mold. In addition, aflatoxin has a low solubility in water, making it more difficult to handle. If you find that a peanut has gone bad, then the bowl of peanuts or the bag of peanuts stored may have bred aflatoxin, and for food safety reasons, they should be thrown away.

Long-standing rice

In order to avoid waste, we often meet elders who eat leftovers all year round, even if the rice has a bit of odor, they still eat it. Little do they know that spoiled rice is the most likely to produce aflatoxin. Therefore, when cooking, cook only as much as you eat, and it is best to eat it all on the same day without leaving any leftovers.

Bitter nuts

Friends who like to eat melon seeds, peanuts, and pistachios have probably encountered a few that are too bitter to swallow, and many choose to swallow them quickly to shorten this unpleasant taste.

However, the bitter taste of nuts such as melon seeds comes from aflatoxin produced during the moldy process. Therefore, if you eat bitter nuts, you must spit them out and rinse your mouth in time.

Poor quality oil

Sesame paste, peanut butter and sesame oil that everyone loves to eat, some unscrupulous merchants use bran sesame seeds, shrunken peanuts and even spoiled sesame seeds and peanuts as raw materials in order to reduce production costs. The spoiled peanuts contain aflatoxin.

On the other hand, although some peanuts and sesame seeds look normal, aflatoxin has already appeared inside. The presses in small workshops or household oil presses are simple in technology and lack the technology to remove harmful substances, so they cannot refine the raw materials. Therefore, when choosing products such as sesame oil and peanut butter, try to choose products with reliable reputation.

① Quickly identify and discard decisively. Do not eat grains that have been stored in a hot and humid environment for a long time, especially those that have become moldy.

② Food containing aflatoxin cannot be sterilized after cooking. The decomposition temperature of aflatoxin is about 280 degrees, so it cannot be sterilized by general cooking methods.

③Aflatoxin in rice is mainly located on the surface. When washing rice, rub it with your hands 3-4 times to remove 80% of the aflatoxin.

④ Old vegetable oil, especially peanut oil, may contain a small amount of aflatoxin, so do not eat raw oil; when heating the oil, wait until a little smoke comes out, add a small amount of salt and boil it. The iodide in the salt can eliminate some of the toxicity of aflatoxin.

02

Benzopyrene: The higher the temperature, the more rampant I become

Barbecue, bacon, and oil fumes, when we hear these familiar names, most people know that these things are unhealthy, but do you know what carcinogenic factors they contain?

Benzopyrene is a type 1 carcinogen that can cause many types of cancer. Benzopyrene in food comes from two sources: the first is the combustion of coal, charcoal, oil, etc., especially the smoke caused by incomplete combustion, which comes into direct contact with food and adsorbs on the surface of food; the second is the thermal cracking reaction of fat, cholesterol, protein and carbohydrates contained in the food under high-temperature cooking conditions to form benzopyrene.

Therefore, the above two reasons explain why grilled and smoked meats contain more benzopyrene. Studies have reported that the benzopyrene content in the oil dripping from grilled meat is 10-70 times higher than that in animal food itself.

So, besides barbecue, which foods we often come into contact with are likely to contain benzopyrene?

High temperature fried foods

Repeated use of high-temperature vegetable oils, over-frying, and stir-frying of foods will all produce benzopyrene. The content of benzopyrene in burnt foods is 10-20 times higher than that in ordinary foods.

Cooking fumes

According to measurements, the fumes produced when cooking oil is heated to 270 degrees Celsius contain compounds such as benzopyrene. Therefore, many of us make some mistakes in our daily lives, such as waiting for the oil in the pan to smoke for a long time before putting vegetables in, or continuing to fry after frying a dish without washing the pan. Both of these practices are likely to produce benzopyrene.

Smoked food

The charcoal used for smoking and grilling contains a small amount of benzopyrene, which may enter the food along with the smoke at high temperatures. On the other hand, the incomplete combustion of sugar and fat contained in the smoked fish or meat itself can also produce benzopyrene.

① Limit the amount of fried, smoked and grilled foods you eat.

② Stay away from fried, smoked and grilled stalls, and leave immediately after buying.

③ When eating barbecue occasionally, choose an environment with good ventilation and exhaust conditions, and make sure the meat does not burn.

④ When frying foods yourself, try to control the oil temperature during frying, shorten the frying time, and make sure the color after frying is not too dark, a light yellow color is fine.

⑤ When frying food, be careful to remove the small residue or debris remaining in the oil, because after long-term and repeated frying, they will turn black and mushy, and produce many harmful substances.

⑥ Never reuse frying oil.

⑦ Be sure to clean the pan after frying the first dish before frying the second dish.

⑧Do not leave the oil smoking for a long time.

⑨If you must eat smoked, grilled, and fried foods, do not pair them with other high-protein foods. Instead, eat them with green leafy vegetables and raw vegetables.

03

Nitrite: The longer it is stored, the more harmful it is

There are also two sources of nitrite in the food we usually eat.

One is artificially added as a food additive. In fact, nitrite is a food additive permitted by various countries, mainly used in meat products. It can make the meat color more red and pleasing to the eye. For example, sausages, ham, luncheon meat and other "red beauty" processed meats.

Second, the nitrate content in vegetables is relatively high, and nitrate can be converted into nitrite by "nitrate reductase" during the storage of vegetables.

Long-lasting green leafy vegetables

Due to excessive nitrogen fertilizer application, the nitrate content in vegetables is often high. If stored for a long time, nitrate can be converted into nitrite by the plant's own "nitrate reductase" during the storage of vegetables.

Therefore, the nitrite content in fresh vegetables is very low. If you buy green leafy vegetables and do not eat them immediately, but leave them for two or three days, the nitrite content in them is likely to increase.

Overnight dishes

When vegetables are eaten, they are repeatedly tossed by several pairs of chopsticks, which has already fully inoculated bacteria. Even if the leftovers are placed in the refrigerator after eating, bacteria will slowly grow. The longer they are stored, the more nitrites are produced.

Pickles

During the pickling process, the nitrate in the vegetables will be converted into nitrite. However, it is necessary for everyone to know a general rule: the nitrite content of pickled vegetables is the highest in the first one or two weeks, and then gradually decreases, and the content will be very low after 20-30 days.

According to Zhong Kai, an associate researcher at the National Food Safety Risk Research Center, patients who suffer from pickled vegetable poisoning in clinical practice generally eat "exploded pickled vegetables," which are vegetables that have been pickled for a very short time.

Salad

When the weather gets hot, many families like to eat some cold dishes, and sometimes they put too much in the refrigerator. Although the cold dishes still look fresh and crisp after a few days, the nitrite content in them is higher than that of leftovers after one or two days.

① Eat fresh vegetables, do not eat rotten vegetables.

②Try not to eat overnight cooked food.

③ There is a tendency to choose some vegetables with low nitrate content. For example, root vegetables and green leafy vegetables have the highest nitrate accumulation, while melon vegetables have the lowest content, and the difference between the two can be more than 20 times.

④ Pickled vegetables should be purchased from regular manufacturers. If you make pickles at home, you should control and extend the pickling time.

04

Formaldehyde: I may also be added to food

Most of us know formaldehyde from decoration materials. It is also a type 1 carcinogen. The source of formaldehyde in food is not exactly the same as the previous carcinogens. It can be said that it is basically added artificially for the purpose of preservation and beautification bleaching.

Baby cabbage and other fresh vegetables

Baby cabbage will rot quickly if left alone under normal circumstances. However, the media has frequently reported that vegetable markets use formaldehyde to treat baby cabbage, which can keep it fresh for a long time and facilitate trading.

Aquatic products

In order to prevent spoilage and increase weight, formaldehyde is most likely to be added to squid, beef tripe, yellow throat, duck intestines and other water-soaked products by illegal vendors. Because water-soaked products such as squid treated with formaldehyde can not only prevent spoilage for a long time, but also double their weight, thus making more profits.

Boiled peanuts and edamame from food stalls

In summer, many people like to eat at food stalls and drink beer at night, and if they have a plate of boiled peanuts, it will be even more enjoyable.

We know that boiled peanuts will quickly become sticky and rotten if left at room temperature in summer, even if they are refrigerated. However, the media has repeatedly reported that boiled peanuts sold by illegal vendors often remain at room temperature for a long time without rotting. The reason is that they have been treated with excessive formaldehyde.

There is only one piece of advice regarding formaldehyde in food: listen to your mother and go home for dinner.

Having said so much, we may find that carcinogens seem to be everywhere, but we should still face this problem rationally.

We must be clear that the occurrence of cancer is the result of a combination of factors, and external carcinogens are one of them. Repeated exposure to carcinogens does not necessarily lead to cancer, but it will definitely increase the probability of cancer. Therefore, we can reduce the probability of cancer by paying more attention to our daily lives, eating healthily, and avoiding foods that clearly contain carcinogens.

Photo/ Fat Bear

Review/ Ji Xiaohui

Original article, no reproduction without authorization

Chongqing Science Popularization Base/Member of China Medical We-Media Alliance

Chongqing Municipal Science and Technology Commission Science and Technology Communication and Popularization Project

National Health Commission National Basic Public Health Service Health Literacy Project