“Drinking milk causes cancer” has caused controversy. How should the health standards of milk be defined?

"A cup of milk a day makes Chinese people strong" is a classic milk slogan that many people are very familiar with. Drinking milk regularly is good for health. my country has been vigorously promoting the benefits of drinking milk, hoping that everyone can drink milk every day.

The 2022 version of the Dietary Guidelines was recently released. Compared with the 2016 version, the new guidelines place special emphasis on milk intake. The original 2016 version recommended 300 grams of milk and dairy products per day, while the 2022 version has increased the recommended amount to 300-500 grams per day.

Chinese Nutrition Society

This change further confirms the importance of drinking milk and also reflects the importance our country attaches to drinking milk.

Even so, there are still many different opinions on drinking milk, with mixed reviews and even some people strongly opposed to drinking milk. Let's talk about the 10 things that people "poke" about milk the most.

1. Is drinking milk harmful to health and can it also lead to precocious puberty?

There is a rumor that milk contains hormones, which is harmful to the health of adults and will cause precocious puberty in children!

The truth is: It won’t!

Let’s talk about hormones first. There are two sources of estrogen in milk. One is the natural estrogen contained in milk, which comes from the natural secretion of cows during milk production. The other is artificially added estrogen, which is mainly used to treat infertility and cow illness. [1]

The content of natural estrogen in milk is very low and has no harm to the human body. Many common natural foods contain estrogen or estrogen-like substances, such as meat, soy products, etc. Even breast milk contains estrogen, and the content is often higher than that in milk.

As for artificially added estrogen, the state will of course have restrictions. my country's "Regulations on Veterinary Drug Administration" has clear provisions on estrogen drugs, and related drugs must not be detected in animal foods. Therefore, as long as the milk is purchased from a regular manufacturer, there is no need to worry too much about estrogen issues.

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In addition, there is currently no evidence that drinking milk can cause early puberty in children or harm their health. On the contrary, a number of studies have shown that the intake of milk and its products can increase the bone density of children, adolescents and postmenopausal women, and is beneficial to the growth and development of children. [2]

Drinking milk will not cause cancer in adults. Studies have shown that milk and its products are not associated with the risk of breast cancer and prostate cancer. Regular consumption of milk may also reduce the risk of breast cancer by 16%, and drinking 200 grams of dairy products a day can reduce the risk of colon cancer by 7%. [2]

Overall, as long as the milk is purchased from a regular manufacturer, there is no need to worry about cancer and you can drink it with confidence.

2. Why is drinking milk recommended?

Because most people in my country do not drink the recommended amount of milk, according to the "Scientific Research Report on China's Dietary Guidelines 2021", in 2015, the per capita milk intake in my country's cities only reached 14% of the recommended amount in the 2016 edition of the Dietary Guidelines, and it was even lower in rural areas.

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In other words, most people in my country do not drink enough milk. Milk is a good source of calcium, and if you do not consume enough milk for a long time, you may increase the risk of calcium deficiency.

In addition to calcium supplementation, milk can also provide high-quality protein and vitamin B2. The lactose in milk can also promote the absorption of minerals such as calcium, iron and zinc.

3. Is it scientific to drink one pound of milk every day?

The reason why we recommend drinking one pound of milk every day is that for special groups with high calcium needs, even if they insist on drinking 300 ml of milk every day, it is still difficult to supplement calcium. For example, adolescents who are growing and developing, women in the middle and late stages of pregnancy, breastfeeding mothers, and people over 50 years old.

If you drink 300 ml of milk every day, you can supplement 321 mg of calcium. This is obviously not enough for people with high calcium requirements, which means they need to consume 500 to 900 mg of calcium from other foods.

In addition to milk, green leafy vegetables and soy products are also sources of calcium supplementation, but due to the influence of phytic acid, oxalic acid, etc., the absorption rate is mostly lower than that of milk. For example, the calcium absorption rate of tofu is only 15%; the calcium content of celery is higher than that of milk, at 191mg/100g, but the oxalic acid content is as high as 231mg/100g, and the available calcium is only 79mg/100g; the calcium content of leek is 105mg/100g, and the oxalic acid content is as high as 162mg/100g, and the available calcium is only 34mg/100g. [3] Therefore, it is necessary to increase the intake of milk to 1 jin per day.

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4. Should I stop breastfeeding if I am lactose intolerant?

Lactose intolerance is very common in my country. People with this condition lack lactase, which breaks down lactose, in their intestines. They experience discomfort after drinking milk, such as bloating, abdominal pain, and diarrhea. But even if you have lactose intolerance, it does not mean you need to stop breastfeeding. It is recommended to try the following 4 methods:

① Drink yogurt: During the fermentation process of yogurt, lactose will be fermented by microorganisms to produce lactic acid, which reduces the lactose content and relieves the symptoms of lactose intolerance. In addition, studies have shown that increasing yogurt intake can improve the symptoms of lactose intolerance. [2]

② Drink zero lactose or low-lactose milk: A special process is used to hydrolyze the lactose in the milk, making it very suitable for patients with lactose intolerance.

③ For people with only very mild lactose intolerance, they can try to improve their lactose tolerance: drink 60-120 ml of pure milk 2-3 times a day during or after each meal for 3 weeks to gradually induce the intestine to enhance its tolerance to lactose. [4]

④ Low-salt cheese: According to the protein ratio, 10 grams of cheese is equivalent to 100 grams of milk.

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5. I just don’t like drinking milk. How can I supplement my nutrition?

Some people just don't like the taste of milk, some are allergic to dairy products and really can't enjoy it, and some people are still skeptical about milk and don't want to drink it. So how can these people get enough calcium?

For people who don’t like the taste of milk, you can make milkshakes with milk and fruits, such as strawberry milkshake, banana milkshake, mango milkshake, etc. The taste is mostly acceptable; you can also use milk or milk powder to make egg custard and steamed buns; yogurt and cheese are also good choices.

Calculated according to the protein ratio: 12.5 grams of milk powder is equivalent to 100 grams of milk.

For people who are allergic to milk, they cannot eat any dairy products and often worry about insufficient calcium intake. It is recommended to choose vegetables with high calcium content, such as rapeseed, Chinese cabbage, radish greens, fennel, and coriander. For vegetables with high oxalic acid content, such as spinach, amaranth, water spinach, celery, etc., they can be blanched before eating. Eat 300-500 grams of vegetables every day. One fist is about 100 grams after cooking.

It is recommended to eat at least 50 grams of soybeans, such as 2 fists of northern tofu or 4 pieces of dried tofu or 1.5 fists of shredded tofu.

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In addition, you can also take appropriate calcium supplements. It is recommended to choose small doses, preferably containing 100 to 300 mg of calcium per tablet, which can be supplemented flexibly.

6. What should I do if I get acne after drinking milk?

Many people actually like to drink milk, but what is frustrating is that they get acne all over their face after drinking milk. This may be because they are intolerant to milk. The casein in milk can increase the secretion of insulin and IGF-1, leading to acne. [5]

In particular, skim milk may be more serious than whole milk, so the "Guidelines for the Treatment of Acne in China (2019 Revised Edition)" also mentioned that if you have acne, you should pay special attention to limiting the intake of skim milk. You can try sugar-free yogurt and low-salt cheese.

7. Are milk and citrus fruits incompatible?

There is a rumor among the people that milk and citrus fruits are incompatible and cannot be eaten together. When milk meets the citric acid in oranges, it will denature and precipitate, thus causing stones.

The truth is: precipitation may indeed occur when milk and citrus fruits meet, but this is because the organic acids in the fruits break the acid-base balance. When the pH just reaches the isoelectric point of the protein, the protein particles in the milk are easily collided and condensed due to the weakened intermolecular forces, thus producing flocculent precipitation. However, these precipitates are also edible, and many cheeses are produced in this way.

Even if you don't eat it with fruit, milk will precipitate and coagulate when it encounters stomach acid. Therefore, milk and citrus fruits can be eaten together without any risk of poisoning or stones.

8. Can drinking milk and applying milk help whiten your skin?

Can milk whiten your skin if it is white? Black people also drink milk, but their skin color is still dark.

The main components of milk are water, protein, fat, calcium, etc. These ingredients have no special effect on whitening. Even if you wash your face with milk every day, it will not whiten your skin.

Skin color is closely related to genetic and environmental factors, and cannot be changed by eating any kind of food. Drinking milk is highly recommended, but don't expect to whiten your skin; as for washing your face with milk, don't waste it.

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9. Are preservatives secretly added to milk with a long shelf life?

Many milks on the market have a shelf life of up to 6 months, so some people think that preservatives are secretly added.

In fact, there is no need to add preservatives to milk. The shelf life depends on the method of sterilization of the milk.

The shelf life of pasteurized milk is generally short, usually 7 days, and it needs to be refrigerated; while milk that is ultra-high temperature sterilized kills almost all microorganisms and bacteria during the sterilization process, so it can be stored for a long time without preservatives, generally up to 6 months, and can be stored at room temperature.

10. Is milk in transparent packaging bags fresher and more nutritious?

There are many milks in transparent packaging bags on the market now. The price is relatively high, and you can directly see the true color of the milk, giving people a very fresh feeling. Many consumers also prefer to buy this kind of milk, thinking that it is more nutritious and safer to drink.

In fact, transparent packaging does not mean that milk is fresher or more nutritious. Vitamin B2 in milk is a photosensitive substance and is unstable under light. Milk in transparent packaging is often directly exposed to sunlight and light, which may increase the loss of vitamin B2 in milk.

Opaque milk packaging can be stored away from light, thereby better protecting the nutrients in the milk.

Summarize:

From the perspective of calcium supplementation and disease prevention, 300 to 500 ml of milk per day is necessary. If you particularly like to drink milk and drink more than 500 ml per day, it is recommended to choose low-fat milk, or reduce the intake of other fats and oils appropriately, and avoid exceeding the total energy limit.

Author | Xue Qingxin, member of Chinese Nutrition Society, registered dietitian, registered nutrition technician, health manager, public nutritionist

Review | Song Shuang, Associate Researcher, Institute of Nutrition and Health, Chinese Center for Disease Control and Prevention

Editor | Ding Zong

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

The pictures in this article are from the copyright gallery and are not authorized for reproduction.

References:

[1] Lan Jianli, Nian Jingqi, Yang Xiaobo, et al. Analysis and control of estrogen in milk and dairy products[J]. China Dairy, 2014, (6): 45-46.

[2] Chinese Nutrition Society. Dietary Guidelines for Chinese Residents[M]. People's Medical Publishing House. 2022

[3] Yang Yuexin, Ge Keyou. Chinese Nutrition Science Encyclopedia 2nd Edition (Volume 1)[M]. People's Medical Publishing House, 2019.109

[4] Chen Jian, Sai Xiaoyong. Research progress on lactose intolerance[J]. Chinese Journal of Epidemiology, 2016, 37(2):299-302.

[5] Xiao Qingqing, Gao Shangpu, Song Yu. Research progress on diet in the pathogenesis of acne[J]. World Latest Medical Information Abstracts, 2019, 19(92): 92-93. DOI: 10.19613/j.cnki.1671-3141.2019.92.045.