February 2024 "Science" Rumors List: Do you need to drink 8 glasses of water a day to be healthy? The faster you drive, the more fuel efficient you will be?

The list of "scientific" rumors for February 2024 is revealed! Eating yeast-containing pasta regularly can damage the stomach and cause cancer? Can snow be used to treat frostbite? Is there no problem with taking cephalosporin with alcohol? The truth >>

The monthly "science" rumor list is guided by the Beijing Association for Science and Technology, the Beijing Municipal Cyberspace Administration, and the Capital Internet Association, and jointly released by the Beijing Science and Technology Journalists and Editors Association and the Beijing Regional Website Joint Rumor-Refuting Platform, and is supported by the Science and Technology Journalists and Editors Professional Committee of the China Science Writers Association, the China Evening News Science Editors and Journalists Association, the Shanghai Science Communication Association, and the Institute of Science and Technology Information of the Beijing Academy of Science and Technology.

1. Does eating yeast-containing pasta regularly damage the stomach and cause cancer?

gossip:

Eating pasta made with yeast regularly is harmful to the stomach, can easily cause gout, and may also pose a risk of cancer.

the truth:

Yeast produces carbon dioxide during the fermentation of steamed bread, bread and other pasta, but the fermentation and gas production capacity of yeast is affected by many factors such as temperature, dough composition, pH value, etc. If the temperature exceeds 60 degrees Celsius, yeast cannot survive, let alone ferment and produce gas. Therefore, there is no need to worry that freshly steamed and baked steamed bread will produce a lot of carbon dioxide and hurt the stomach.

From the perspective of ingredients, the purine content of every 100 grams of yeast is 559 mg, which can indeed be classified as a high-purine substance, but yeast is only a leavening agent and is not consumed as food alone. From the analysis of intake, the recommended amount of yeast added is 0.5%, that is, 5 grams of yeast can ferment about 1 kilogram of flour. Calculated based on 100 grams of staple food per person per meal, the purine content is basically negligible, so the impact on gout patients is minimal.

Some people believe that yeast at high temperatures will transform the protein and sugar in flour to produce new aromas, colors and flavors, and then undergo the Maillard reaction (which refers to the polymerization and condensation reactions of amino compounds and carbonyl compounds at room temperature or when heated, ultimately generating brown or even brown-black macromolecules called melanoidins or pseudo-melanins), which will produce some harmful carcinogens. But in fact, yeast mainly works during the dough-making stage, and will be inactivated in an environment above 60 degrees Celsius, and will not react at high temperatures, so the so-called carcinogenicity has nothing to do with it.

2. Can snow be used to treat frostbite?

gossip:

There has long been a popular belief that frostbite can be treated by friction massage with snow.

the truth:

There are several possible sources for this statement: First, it is influenced by movies, novels, and other film and television works. Second, in the wild, when there is a lack of rescue equipment, people will use some temporary methods, and snow is the easiest to find. Third, compared to ice, people think that snow is warmer, even warmer than the skin temperature of frostbitten parts, and can keep warm. Some people also believe that massaging with soft snow can relieve pain.

But under modern medical conditions, it is wrong to use snow to treat frostbite. Not only is it difficult to improve blood circulation, it may also cause new injuries.

The correct way is to leave the frostbitten environment and return to normal temperature once limb frostbite occurs. Use warm water of 30 to 40 degrees Celsius to gradually restore the skin's surface temperature perception. Oral hot water can also help increase the body's circulation temperature. But do not soak the skin in hot water, and do not roast or rub the frostbitten skin. The drastic temperature change is not conducive to the recovery of the skin. If blisters and ulcers appear, do not cut them open. You can first apply frostbite cream and antibiotic ointment for protection, then use electric hand warmers or warm water bags to gradually restore the body surface temperature, and then seek medical treatment.

3. Is there anything wrong with taking cephalexin with alcohol?

gossip:

Some people drink alcohol after taking cephalosporin antibiotics, and nothing happens except a little stomach discomfort.

the truth:

Many cephalosporin antibiotics can cause a "disulfiram-like reaction" when in contact with alcohol. The severity of the reaction is related to the dosage, alcohol consumption, and personal constitution. Sometimes nothing happens after taking "cephalosporin with alcohol", which can be considered a blessing. But life is only once, and there is no room for luck. In many cases, a disulfiram-like reaction is not "nothing at all" and may even be life-threatening.

Therefore, medical experts recommend that you should not drink alcohol within 7 days after taking cefuroxime, and you should not take cefuroxime within a week after drinking alcohol. Generally speaking, milder disulfiram-like reactions can heal on their own, and symptoms can be relieved by drinking plenty of water, resting, etc. If the symptoms are severe or do not improve, you should seek medical attention in time.

4.Is the rice in self-heating rice fake rice?

gossip:

The rice in self-heating rice is fake rice and is harmful to the body if eaten.

the truth:

Whether it is reconstituted rice, rice that is cooked and then dried, or sterile rice, they are all made from real rice, but the processing technology is different. The purpose is to allow everyone to eat rice quickly and conveniently, saving time-consuming processing.

There are currently three main types of self-heating rice on the market: the first type is to crush the rice, then add starch, and then extrude and cook it into rice grains. This type of rice is also called reconstituted rice. The starch of this processed rice will gelatinize faster and can be cooked quickly.

The second type is made by cooking rice and then drying it. After cooking, the starch of the rice is gelatinized, and then it is quickly dehydrated, which can make the gelatinized starch molecular structure more stable, prevent the aging of the starch, and cook quickly. This is actually the same principle as the instant noodles we usually eat.

The third type is sterile rice, which is actually cooked rice that is sterilized and then sealed for storage. When you eat it, you only need to heat it in the microwave for two to three minutes.

5. Do I need to drink 8 glasses of water every day to be healthy?

gossip:

Drinking 8 glasses of water (about 2 liters) a day is good for your health, otherwise you will be dehydrated.

the truth:

People of different ages, genders and countries have different water requirements. The one-size-fits-all health advice of "8 glasses of water" is not suitable for providing precise health guidance to individuals.

The daily "water turnover" of the human body is the total amount of water exchanged, which includes the water we take in and the water we lose, and largely reflects people's water needs. However, water turnover is not equal to the actual amount of drinking water we drink every day. For example, a man in his 20s has a daily water turnover of 4.2 liters, but he does not need to drink 4.2 liters of water, because human metabolism and surface water exchange can provide 15% of it, and the remaining 85% of the water requirement comes from food and drinking water. If food and drinking water are half and half, the average daily water intake of men in this age group is 1.5-1.8 liters.

In contrast, women drink less water because their non-fat content is lower than that of men. For example, a woman in her 20s may drink 1.3-1.4 liters of water per day.

6. Do biological drugs need to be stored in refrigeration during winter?

gossip:

The outdoor temperature is cold in winter, so there is no need to refrigerate biologic drugs such as insulin and hormones.

the truth:

Insulin, hormones, etc. are biological agents. After freezing, their proteins will denature, which will cause the drugs to become ineffective. Generally speaking, it is recommended that unopened biological agents be stored in a refrigerator at 2 degrees Celsius to 8 degrees Celsius. Freezing and refrigeration are completely different concepts. Freezing usually refers to minus 20 degrees Celsius to 0 degrees Celsius.

Winter in the north is often cold outdoors, and the temperature may drop below 0 degrees Celsius. If insulin and other biological agents are placed directly outdoors, they are very likely to be "frozen". Even if they are thawed, they cannot be used normally. When storing insulin, hormones, blood products and other biological agents in the refrigerator, it is not recommended to place them in the storage compartment on the refrigerator door, because opening and closing the refrigerator door may cause the temperature to be unstable, and the vibration caused by opening and closing the door may also destroy the molecular structure of the biological agent, thereby damaging the drug.

7. The faster the car goes, the more fuel efficient it is?

gossip:

When driving on the highway, the faster you go, the more fuel you save.

the truth:

When a car is driving, when the speed reaches a certain value, there is a minimum fuel consumption, which is called "economic speed". When it is lower than the economic speed, the engine load is small, the combustion is not complete, and the fuel consumption is high; when the speed reaches 80% to 90% of the engine load, the fuel economy is the best; when it is higher than the above speed, as the intake speed increases, the intake resistance increases, and the drag coefficient also increases, resulting in a significant increase in fuel consumption.

A car's "economical speed" depends on a variety of factors, including vehicle type, driving conditions, engine efficiency and aerodynamics, but it is generally concentrated in the speed range of 60-90 km/h.

(Image source: Visual China, this issue's content sources: CCTV News, China Internet Joint Rumor Refutation Platform, Beijing Science and Technology News, Beijing Daily Client, Tencent Jiuzhen, Health Times, Voice of the Chinese Academy of Sciences)