Is the freezer a "safe" for food? Here comes the July 2023 scientific rumor list →

Should you drink a lot of boiled water immediately after getting a heat stroke? Should you not drink ice water after exercise because it will damage your health? Is the freezer a universal "safe" for food? Should you take more folic acid when preparing for pregnancy, the earlier the better? ... Do these statements sound familiar? Are they true knowledge or rumors?

On August 1, Science Rumor Refutation, China Internet Joint Rumor Refutation Platform, and the "Study Strong China" learning platform jointly released the July Science Rumor List, revealing the truth about six "health rumors" and "pseudoscience."

1. Once you have heatstroke, drink more boiled water to replenish water

Rumor content : After suffering from heatstroke, you will sweat a lot and easily become dehydrated. You should drink plenty of boiled water immediately to quickly replenish a lot of water.

Truth Interpretation : This practice is incorrect. If a person suffering from heatstroke drinks a large amount of water in a short period of time, it will cause acute gastric retention and may also lead to heat cramps.

After suffering from heatstroke, drinking a lot of boiled water will not only accelerate the electrolyte disorder in the body, aggravating symptoms such as muscle cramps and fatigue, but may also cause hyperreflex sweating, resulting in a large loss of water and salt in the body. In severe cases, it may induce heat cramps.

The correct way is to drink water in small amounts and multiple times, no more than 300 ml each time. In addition, try to drink light salt water to correct the electrolyte disorder in time. After the symptoms of heat stroke are relieved, you can drink some warm water in small amounts and multiple times.

Source: People's Daily Health Client Check Disease

2. The temperature in Beijing from June 30 to July 2 this year reached 43℃ to 44℃

Rumor content : A netizen posted a "temperature forecast data released by the US Embassy in China" on the Internet. The data showed that the temperature in Beijing reached 43℃, 44℃ and 43℃ on June 30, July 1 and July 2 respectively.

Truth interpretation : This is not the case. The highest temperatures monitored on June 30, July 1, and July 2 were 39°C, 39°C, and 38°C respectively, and the so-called forecast data of 43°C, 44°C, and 43°C were not released by the US Embassy in China.

This data comes from the GFS (Global Forecast System) global numerical weather forecast system, which comes from the National Centers for Environmental Prediction (NCEP) of the United States, but this "numerical weather forecast system" is not a weather forecast suitable for ordinary people to refer to directly.

The weather forecasts that people see on TV and in weather software are all the results of "refined" numerical weather forecasts. For example, forecasters first combine local actual conditions with computer calculation results, carefully check radar echoes, infrared images, water vapor images, etc., and make judgments based on their own professional knowledge. At the same time, they also need to consult with forecasters from other meteorological bureaus to make accurate weather forecasts.

Source: Tencent

3. Don’t drink ice water after exercise, drinking ice water is harmful to your health

Rumor content : After exercising in the summer, even if you are very thirsty or hot, you cannot drink ice water, otherwise it will cause great harm to your body.

Truth interpretation : This statement is inaccurate. You can drink ice water after exercise because it can quickly help cool down the core of the body and avoid heat stroke or dehydration.

Although you can drink ice water after exercise, it does not mean that everyone should drink ice water after exercise, because some people do not have the habit of drinking cold or ice water. The temperature of ice water is too low and may irritate the stomach and intestines, causing stomach discomfort, such as cramps.

In general, you can drink ice water after exercise, but personal habits should be considered. For those who can't stand ice water, it is recommended to drink warm water after exercise, and then drink water slowly. The amount should not be too large, about 200 ml each time, and replenish it gradually.

Source: Tencent

4. Eat more folic acid when preparing for pregnancy. The earlier you eat, the better.

Rumor content : If a woman is preparing to become pregnant, she should take folic acid in advance, the earlier the better, and the more the better.

Truth : Not necessarily! There is no need to take too much too early.

Folic acid is a water-soluble vitamin that participates in the metabolism of amino acids and nucleic acids. It plays an important role in cell proliferation, tissue differentiation, and body growth and development. It is one of the most important nutrients during the pregnancy preparation period. Folic acid deficiency can easily lead to fetal neural tube defects.

Since folic acid cannot be synthesized in the human body and its utilization rate from food is low, women need to take additional folic acid supplements during pregnancy preparation. However, the earlier you take folic acid, the better, and the more you take, the better. It is recommended to take folic acid from the first three months of pregnancy preparation to the third month of pregnancy. The recommended daily intake is 400-800 μg.

Source: Science Refutes Rumors

5. People who love to laugh will not suffer from depression

Rumor content : People with depression are unhappy and have no interest in life. People who are sunny and love to laugh will not suffer from depression.

Truth interpretation : This is a common misunderstanding. People with cheerful and lively personalities may also suffer from depression.

There is also a type of depression called "smiling depression". In addition to the common depression patients' characteristics such as sensitivity, inferiority, and excessive introspection, this type of depression patients also usually have personal perfectionism and histrionic personality disorder.

They often indulge in playing the perfect persona, or are afraid that their emotions will affect those around them, and are unwilling to burden others, so they hide their depression and choose to "treat others with a smile." Even if they are depressed, they will still smile in front of others, making them look happy and cheerful, and mistakenly believe that they are living a happy life, which makes it difficult for people to discover their depressive tendencies.

Therefore, we cannot simply judge depression based on a person’s personality.

Source: Science Refutes Rumors, Science Popularization China

6. The freezer compartment of the refrigerator is a "safe" for food

Rumor : Food can be preserved for a long time in the freezer.

Truth interpretation : The answer is No! Refrigerating or freezing food cannot completely inhibit the growth of bacteria.

There is a type of "psychrophilic bacteria" in the refrigerator that prefers low-temperature environments. "Psychrophilic bacteria" can still survive below zero, and -15℃ to -20℃ is their suitable growth temperature. If the food stored in the refrigerator happens to be contaminated by this type of bacteria, the food will become a "nutritional place" for their growth and reproduction.

Listeria is the most common "psychrophilic bacteria" that hides in household refrigerators. Healthy adults infected with Listeria will experience mild flu-like symptoms. Special groups with weak cellular immune function are prone to sudden fever, severe headache, nausea, vomiting, diarrhea, sepsis, meningitis, etc. after infection. Pregnant women may also suffer from miscarriage.

Source: Science Popularization China

About the Science Rumors List

Released by the China Association for Science and Technology, the list is reviewed by experts every month. Based on criteria such as timeliness and harmfulness, hot rumors are selected for special interpretation and pushed across the entire network.

Jointly published : Scientific rumor-busting platform, China Internet Joint Rumor-busting Platform, "Study to Strengthen the Country" learning platform

Supported platforms : Tencent Jiuzhen, Weibo Rumor Refutation, Toutiao Health, Baidu Knows, Toutiao Rumor Refutation, Douyin, Dad Review, NetEase Health

Scientific rumor debunking : Sponsored by the China Association for Science and Technology, the National Health Commission, the Ministry of Emergency Management, the State Administration for Market Regulation and other ministries and commissions, guided by the Central Cyberspace Affairs Commission, and jointly created by national societies, authoritative media, social organizations and scientific and technological workers, it aims to effectively improve the dissemination, guidance and influence of rumor debunking information, so that rumors can stop at the wise and let science outrun rumors.

List of review experts (in order of the number of strokes of surnames)

Wang Qian, Chief Physician of the Emergency Department, the Third Medical Center, PLA General Hospital

Zhang Yu, researcher at the Chinese Center for Disease Control and Prevention, doctor of medicine, and master's supervisor

Chen Peng, Associate Professor, Department of Communication, Nankai University

Han Hongwei, Researcher at the National Food Safety Risk Assessment Center

Dai Teqi, Associate Professor, Faculty of Geographical Sciences, Beijing Normal University

This article is produced by "Science Facts" (ID: Science_Facts). Please indicate the source when reprinting.