Myth 2: Teacher Zhang, a nutritionist at the Nutrition Center of Zhejiang University, said that this statement by netizens has scientific basis. But it is not that instant noodles are poisonous, but that the ingredients of instant noodles contain many substances that the human body does not need. "The liver is the detoxification organ of the human body. As long as the human body ingests unnecessary substances, it will be excreted by the liver, generally 32 days is a cycle. People eat instant noodles, fried puffed food and other foods, and those substances that are not needed by the human body are discharged after liver integration, which requires such a cycle. "
Truth: The following is a separate analysis of the "risk factors" involved in the rumor.
1. How dangerous is BHT?
BHT, whose full name is 2,6-di-tert-butyl-p-cresol, is an antioxidant. In food, it is widely used for antioxidation of oil. Edible oil contains some unsaturated bonds, which will be oxidized in the air to produce the so-called "spicy taste". In fact, before the pungent taste appears, the oxidation has already taken place, and only when some oxidation products reach a certain level will the pungent taste be produced. Some oxidation products are harmful to human body.
The function of BHT is to protect oil by oxidation when it is threatened by oxidation. As a food additive, its safety has been widely examined. The Joint Expert Committee on Food Additives (JECFA) of the Food and Agriculture Organization of the United Nations and the World Health Organization has set the daily allowable intake of BHT at 0.3 mg per kilogram of body weight. For adults, it is roughly equivalent to about 20 mg per day.
According to the current national standard of food additives in China, the dosage of BHT in different foods (including fried noodles) is generally 0.2g per kilogram of oil. According to each package of instant noodles100g, the oil content is usually 20%. If you eat 5 packets of instant noodles every day for several years, BHT in them will not be harmful to your health. Of course, BHT may also come from other foods, but if a person eats five packs of instant noodles every day, he may not be able to eat other foods.
Whether a large amount of BHT affects health is indeed controversial. But internationally, China, the United States and the European Union all allow it to be used. It is not the only antioxidant that can be used in oils and fats. In the food industry, there is also a trend to replace it with other antioxidants, such as vitamin E.
2. How harmful is the polystyrene in the instant noodle bowl?
Another way of saying that instant noodles are "toxic" is that the bowl of instant noodles is made of polystyrene. When heated, it will release monomer styrene, which is carcinogenic.
In 2002, Harvard School of Public Health and other institutions published a comprehensive assessment of the potential health risks of styrene in the Journal of Toxicology and Environmental Health (Part B). The relevant conclusions are summarized as follows:
Styrene is a widely used industrial raw material. Due to the development of modern industry, it also exists in the air, and its typical value is in the order of 1ppb (1ppb equals one billion). In fact, it also exists naturally in some foods, such as strawberries, beef and peppers. In the production of wine and cheese, a certain amount of styrene is also produced.
2. Many studies have been done on the safety of styrene. In terms of carcinogenicity, large doses of styrene showed carcinogenicity to mice. This "large dose" is on the order of tens of milligrams per kilogram of body weight. Other health hazards, such as nerve and respiratory system damage, also require large doses.
3. The place with the highest styrene content in the environment is the reinforced plastic factory. An epidemiological survey found that the incidence of lung cancer and respiratory cancer among factory workers was high. However, further analysis of the data shows that this increase comes from the workers who have the least exposure to styrene in the factory. This shows that the culprit of the rising incidence of cancer in this survey is not styrene, but something else.
4. The current experimental and statistical data do not support the conclusion that styrene is carcinogenic or harmful to health at regular dose. However, due to the limitation of statistical data and experimental results, this possibility cannot be ruled out.
According to the common sense that "everything is toxic, as long as the dose is enough", we should still pay attention to the difference between intake and safety. The safe intake set by JECFA is 0.04 mg per kilogram of body weight per day. The FDA of the United States believes that the styrene released by polystyrene packaging materials can not reach this harmful dose, so it is allowed to be used for food. Europe and Japan also allow it to be used.
In China, the situation is more complicated. According to the hygienic standard of polystyrene resin for food packaging (GB 9692 ~ 1988) and the hygienic standard of polystyrene molded products for food packaging (GB 9689 ~ 1988), polystyrene foam can be used to make disposable tableware. However, due to reasons such as "polystyrene may release harmful substances at high temperature", "white pollution" and "the product quality of illegal enterprises cannot be guaranteed", disposable foamed plastic tableware including polystyrene tableware has been included in the list of "eliminated products" since 2005. A local law prohibiting this kind of tableware has been implemented in one area. Considering the situation abroad, safety analysis and the benefits brought by using it, there have been calls to remove it from the list of eliminated products recently.
Styrofoam is just an option for instant noodle bowls. At present, the instant noodle bowls on the market are made of what materials, which need to be judged according to the specific products. But in any case, the myth that "the dangerous amount of polystyrene intake per kilogram of body weight per day is 0.00 1 mg, and the dissolved amount of a bowl of instant noodles is 0.0 15 mg" is unfounded.
3. What are the "unwanted substances" in the ingredients?
Teacher Zhang, a nutritionist at the Nutrition Center of Zhejiang University, said, "The ingredients of instant noodles contain many substances that the human body does not need." Teacher Zhang didn't explain "which" substances in instant noodle seasoning are not needed by human body, but such a general statement actually has no practical significance.
There is nothing special about the seasoning of instant noodles. Like other auxiliary materials of convenience foods, they are mainly "conventional condiments" such as salt and oil, and some "food additives" such as flavors, pigments, antioxidants and preservatives. Many people regard food additives as "substances that the human body does not need". From a nutritional point of view, these substances are usually really unnecessary. But they each play a specific role in food. For example, antioxidants, without antioxidants, the oil in seasonings may soon deteriorate. The ingredients produced by different instant noodle manufacturers are not exactly the same, but as long as the materials meet the national standards, they will not endanger health.
Most ingredients of instant noodles contain a lot of salt. From the perspective of controlling salt intake, the seasoning of instant noodles is really unhealthy. Some people advocate not adding all of them, which is also reasonable from the perspective of reducing salt intake.
4. Does the liver have a 32-day detoxification cycle?
There are various ingredients in food. Not only processed foods, but also "natural foods" have some ingredients that are "not needed by the human body". There are several possibilities for this substance to enter the human body:
1, which is not absorbed and excreted directly through the gastrointestinal tract. Such as insoluble dietary fiber or solid food insoluble in gastrointestinal tract.
2. It is absorbed into the blood and metabolized into other substances in the liver, which is commonly known as "detoxification".
3. The products decomposed in the liver, or undecomposed substances, are mainly excreted with urine through kidney filtration (a small part is excreted with bile).
4. Some of them reach some parts of the body with blood circulation, where they endanger the normal activities of cells and cause harm.
The first three situations will not cause harm to health. If the intake is too large and exceeds the processing capacity of liver and kidney, the fourth situation will be aggravated.
For instant noodles, qualified products, normal consumption, there will be no fourth situation. In the second and third cases, the speed of decomposition and excretion is determined by specific substances, rather than following the so-called "detoxification cycle" of the liver. That is to say, some substances are discharged quickly and some substances are discharged slowly. Usually, the time of discharging 50% or 90% is used to measure the discharge speed of a substance. The time when the concentration drops by half in a certain tissue is defined as "half-life". If this time is very short, such as a few hours or a day or two, it is considered that this substance "has not accumulated". This is true of all kinds of food additives. If this time is long, such as months or even years, it is considered that this substance will "accumulate" in the body. This is the case with many heavy metal pollutants.
For example, calculated by the concentration of metabolites in urine, the half-life of styrene is 8 to 9 hours; Calculated by the concentration in adipose tissue, it takes 2 to 4 days. The metabolic kinetics of BHT is complex, and the half-life of mice after a single feeding is between 9- 1 1 hour. Other food additives have similar time frames. No matter which number you press, there will be no "32-day detoxification cycle".
When setting the safe intake, JECFA considered the health impact of the maximum possible content of the substance in the body. Therefore, as long as it meets the safe intake standard, it can be considered that it has no impact on health.
Conclusion: The rumor is shattered. Instant noodles themselves are not a kind of "healthy food". Its problems are high calories, single nutrients and more salt. As a convenient food, it should only be used as a temporary emergency food, not as a regular staple food. However, these rumors of "instant noodles are poisonous" are speculations used to create panic, and there is no scientific basis to support them.