In recent years, "wellness" has become a new favorite of social topics.
In the office, everyone shared their health secrets with goji berries in thermos cups, and even swiped their mobile phones to forward the health tips to their loved ones for the first time.
For example, "milk contains hormones and causes cancer", "marine fish is more nutritious than freshwater fish", "eating black sesame pills can prevent hair loss", "the more acidic the fruit, the higher the vitamin C content", "chocolate has white frost is spoiled, can not eat", "food without food additives is healthier, if you want to buy, buy zero added"... Are these health claims reliable?
01
Milk contains hormones and can cause cancer?
Milk is one of the most effective foods to obtain calcium.
However, there are claims on the Internet that there is the hormone IGF-1 in milk, and drinking it will cause cancer. Is this true?
IGF-1, whose full name is "insulin-like growth factor 1", is not a harmful substance added artificially, but a hormone-like protein secreted by cows themselves.
Copyright images in the gallery are not authorized to be reproduced
In addition to cows, the human body also produces this hormone, and adults produce 10 million nanograms per day, and the IGF-1 content in milk on the market is only about 2.45 ng/ml, which is not a concern compared to the amount in the human body.
The U.S. Food and Drug Administration (FDA) and the Joint Expert Committee on Food Additives (JECFA) of the World Health Organization and the Food and Agriculture Organization of the United Nations have both assessed that there is no evidence that IGF-1 causes cancer.
According to organizations around the world that specialize in cancer, drinking milk normally may also reduce the risk of certain cancers.
For example, a 2017 expert report by the World Cancer Research Fund (WCRF) and the American Institute for Cancer Research (AICR) evaluated diet, nutrition, physical activity and cancer risk, in which studies on the relationship between milk and dairy products and cancer risk concluded that dairy product intake reduces the risk of colorectal cancer.
Cancer Research UK believes that consuming dairy products can reduce the risk of bowel cancer. The latest published "Consensus on Food and Health Science Evidence" also clearly mentions:
Milk and its products were not associated with the risk of prostate cancer within the study intake range; Intake of low-fat milk and its products can reduce the risk of breast cancer, and whole milk and its products are not associated with breast cancer risk.
The mainland's dietary guidelines recommend drinking 300 grams ~ 500 grams of milk per day.
But we now drink less than 50 grams of milk a day on average. Worrying about drinking milk causes cancer is really a bit redundant.
02
Can eating black sesame pills prevent hair loss?
It has always been said that eating more black foods such as black sesame seeds and black beans can make hair black, and can gradually reverse white hair.
Merchants also took the opportunity to launch "black sesame pills", which said that they can prevent and treat hair loss, and are loved by many people with hair loss, hair loss, baldness, and receding hairline. Can eating black sesame pills really prevent hair loss?
In fact, black sesame seeds can not prevent hair loss, and may also make you fat.
The reason why everyone thinks that black foods such as black sesame seeds and black beans are good for the health of hair and prevent hair loss, mainly because it is black, and we have always had the traditional culture of "making up for black with black".
Copyright images in the gallery are not authorized to be reproduced
Black sesame seeds and black beans contain rich nutrients and trace elements, if it is due to protein, B vitamins and mineral elements caused by gray hair, eating black sesame seeds and black beans may have certain benefits for hair.
However, the melanin in black foods such as black sesame seeds and black beans does not darken the hair. Because the source of melanin in hair is melanocytes, it uses tyrosine conversion in the body to produce melanin.
The melanin in black sesame seeds and black beans is mainly some polyphenolic pigments, which cannot be directly converted into pigments on hair.
Moreover, some black sesame pills on the market will add a lot of sugar to flavor, and the fat content of black sesame seeds itself is also very high, which means that black sesame pills have a lot of sugar and oil, and if you eat more, it must be healthy, and it may make you fat.
Therefore, don't be superstitious about black food, really want to eat black sesame pills, and pay attention to choosing products with less sugar when buying.
03
The more acidic the fruit, the higher the vitamin C content?
Fruits are rich in vitamin C, but what fruits have higher vitamin C content, many people will think that the more sour the fruit, the more VC, the most typical is lemon.
So, the more acidic the fruit, the more vitamin C it really contains?
The reason why some people have such an impression is mainly because the taste of vitamin C itself is indeed sour, vitamin C also has a name called "ascorbic acid", if you have tasted unsweetened vitamin C tablets, you should have experienced that sour taste.
There are indeed some fruits that taste more sour and contain very high vitamin C, such as sea buckthorn, which contains 204 mg of vitamin C per 100 grams, and sour dates contain 900mg of vitamin C per 100 grams.
However, the taste of fruits will also be affected by the type and content of sugar and organic acids, and there is no one-to-one correspondence with vitamin C content.
For example, people often think that the more acidic - lemon, only 22mg of vitamin C per 100 grams;
Another example is oranges, which only have 33mg of vitamin C per 100 grams, and these acidic legends are "high-vitamin C fruits", and the VC content is even inferior to Chinese cabbage (47mg/100g).
In fact, a large part of the sour taste in fruits comes from organic acids, such as malic acid, citric acid, tartaric acid, etc.
Organic acids are intermediate products of fruit energy metabolism, and the types and composition ratios of organic acids in different fruits are different.
For example, citrus fruits (lemons, oranges, oranges, etc.) mainly contain citric acid, berries (such as grapes, etc.) mainly contain tartaric acid, usually in unripe fruits in greater content, in the process of fruit ripening, some organic acids will be converted into sugar, less sour.
In short, the acidity of fruits is not directly related to the amount of vitamin C, and there is no need to aggrieved yourself for "nutrition"!
04
Is chocolate spoiled with white frost?
Have you ever encountered a layer of "white frost" on the surface when eating chocolate? Some people say that chocolate "white frost" is spoiled and cannot be eaten. Is this true?
In fact, this statement is not accurate.
There are usually two kinds of "white frosts" from chocolate - sugar frosting and fat frosting. They are all caused by changes in the ambient temperature when chocolate is stored.
For example, "frosting", as the name suggests, its main ingredient is sugar. It is often caused by a short period of sharp increase in ambient temperature.
Copyright images in the gallery are not authorized to be reproduced
For example, taking chocolate refrigerated in the refrigerator directly to room temperature is more prone to this problem.
In addition, if the chocolate is placed in a humid environment, small water droplets will appear on the surface, resulting in frosting.
The fat cream, its main ingredient is fat, and the cocoa butter in chocolate is inseparable.
Cocoa butter is a specialty of chocolate, especially high-quality chocolate, which naturally has a fragrant taste and attractive luster, which is also why people love it.
But cocoa butter is very sensitive to temperature. When chocolate is stored above 22°C for a long time, part of the cocoa butter in it will melt and seep onto the surface of the chocolate.
When the temperature drops, the oil will recrystallize on the surface of the chocolate, showing white spots that look like a layer of white frost.
So, can you eat "white frost" chocolate?
In fact, white frost is mainly due to physical changes caused by temperature changes, although it has a certain impact on the appearance and taste of chocolate, but does not affect food safety.
If the taste is okay, it doesn't hurt to eat it; But if it doesn't taste good, throw it away.
After all, eating chocolate isn't it for deliciousness!
05
Are marine fish more nutritious and safer than freshwater fish?
Many people will feel that marine fish live in the blue sea, the environment is better, less polluted, DHA content is higher, safer and healthier. Is this true?
First of all, we must know the reality that in today's globalized world, marine fish are also polluted by the environment, and Japan has to discharge nuclear sewage into the sea.
A common polluting factor in fish is heavy metals.
Copyright images in the gallery are not authorized to be reproduced
For example, a study has tested 10 kinds of fish meat in Beijing market such as heavy metals such as arsenic and other elements, and found that the heavy metal content in marine fish is higher than that of freshwater fish.
Research in Shanghai has also found that the content of heavy metal cadmium in marine fish is also higher than that of freshwater fish.
Another common class of harmful substances in fish is persistent organic pollutants.
Studies have assessed the level of contamination of polybrominated diphenyl ethers (PBDEs) in commercially available fish in Shenzhen and found that the content in marine fish is higher than in freshwater fish.
Concentrations and bioavailability assessments of polychlorinated biphenyls (PCBs) in animal foods sold in Shanghai also found that PCBs concentrations in marine fish were higher than in freshwater fish.
The situation in the United States will not be very rosy. For example, research from Duke University found that methylmercury in the deep sea, because it binds to the molecule of salt (sodium chloride), is more difficult to break down in the environment and more harmful to health.
In fact, several types of high-mercury fish that national health agencies remind everyone not to eat, including sharks, sailfish, mackerel, and tilefish, which are marine fish.
Second, freshwater fish don't necessarily have less DHA than marine fish.
Studies have determined 4 species of freshwater fish (blackfish, baotou, crucian carp, cinnamon) and 6 species of marine fish (anchovy, saury, rainbow trout, pomfret cod, small stripfish) and found that the content of n-3 polyunsaturated fatty acids in freshwater fish is not lower than that of marine fish.
There are also studies comparing 5 commercially available marine fish and 9 commercially available freshwater fish of sea bass, mandarin carp, Chinese sturgeon, silver carp, bighead carp, tilapia, wuchang fish, carp and grass carp;
Mainly analyzing and comparing the EPA and DHA content in fish meat and visceral fat, it was found that the EPA and DHA content in freshwater fish was not lower than that of deep-sea fish, and the highest content was even freshwater fish bass.
In fact, whether it is marine fish or freshwater fish, their nutrition is not much different, if conditions permit, they are healthy ingredients worth eating.
06
Are foods without food additives healthier?
When it comes to food additives, many people now think that it is "technology and ruthlessness", and many people also think that additives are unsafe;
Is it true that buying food only recognizes "no XX additives", "0 additions" and "no preservatives", and feels that such food is safer and healthier?
In fact, as long as it is used fairly, all food additives are safe, and there have never been cases of health damage caused by the rational use of food additives.
Food additives are synthetic or natural substances added to food to improve food quality and color, aroma, taste, and for the needs of preservative, preservation and processing technology.
Its use has undergone a very complex and rigorous scientific assessment, as long as it is used reasonably can ensure safety.
For example, preservatives allowed by the national standard have undergone safety evaluation, and standardized use will not cause damage to the health of consumers.
The role of preservatives is to prevent food spoilage, otherwise some food will be broken before leaving the factory, and may even produce toxins.
For example, the sausages we buy will use preservatives - nitrite, its role is mainly to inhibit the growth and reproduction of botulinum, and botulinum toxin may produce a highly toxic toxin - botulinum toxin during the growth process, which is more toxic than arsenic.
However, some foods that should reasonably use preservatives to ensure safety deliberately do not use preservatives, and manufacturing "0 additions" and "no preservatives" may bury food safety risks.
Those foods that claim to be "XX additive-free", "0 added" and "preservative-free" will not be safer and healthier, most of them are corporate marketing means, don't be superstitious.
Author: Ruan Quang Feng, Director of Science and Technology Department, Kexin Food and Nutrition Information Exchange Center
Review: Gao Chao, associate researcher of the Institute of Nutrition and Health, Chinese Center for Disease Control and Prevention
The cover image and the image in this article are from the copyright gallery
The content of the image is not authorized to be reproduced