Chinese people are not suitable for drinking milk? 85% of Chinese people are lactose intolerant? You have misunderstood for too many years!

Rumor: "Chinese people are not suitable for drinking milk, 85% of Chinese people are lactose intolerant"

Milk is a high-quality source of protein, but there are often claims online that Chinese people’s genes are not suitable for drinking milk because 85% of Chinese people are lactose intolerant and drinking milk will cause diarrhea, which makes many people afraid to drink milk.

Rumor analysis: This statement is not rigorous.

First, the data that "85% of Chinese people are lactose intolerant" confuses "lactose intolerance" with "lactose malabsorption". Secondly, due to the use of advanced testing technology, this data is somewhat exaggerated, that is, people with a little malabsorption are included in the statistics. In addition, internationally, the proportion of Chinese people with lactose malabsorption is relatively normal and not particularly high.

Milk is a food with high nutritional value. Many nutrition guidelines recommend that we drink a glass of milk every day. However, there are often claims online that Chinese people's genes are not suitable for drinking milk, because 85% of Chinese people are lactose intolerant and drinking milk will cause diarrhea. Is it true that Chinese people's genes are not suitable for drinking milk? Is it true that 85% of Chinese people are lactose intolerant? Can lactose intolerant people not drink milk?

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85% of Chinese people are lactose intolerant?

It is said on the Internet that Chinese people are not genetically suited to drinking milk and that 85% of Chinese people are lactose intolerant. In fact, this is a misinterpretation of the data. Chinese people can also drink milk. First of all, the data of "85% of Chinese people are lactose intolerant" confuses "lactose intolerance" with "lactose malabsorption". The "85%" data comes from a study in The Lancet. This study counts lactose malabsorption, not lactose intolerance. The two are actually not the same thing.

● Lactose intolerance refers to a clinical syndrome including abdominal pain, bloating, flatulence, nausea, and diarrhea after consuming lactose or foods containing lactose.

● Lactose malabsorption refers to a situation where the ingested lactose cannot be absorbed by the small intestine due to a lack of lactase.

Lactose intolerance emphasizes a series of digestive tract symptoms caused by undigested lactose entering the large intestine and fermented by bacteria. The symptoms are more obvious and diverse, including abdominal pain, bloating, diarrhea, etc. Lactose malabsorption focuses more on the biochemical state of unabsorbed lactose, and does not necessarily cause symptoms. In summary, lactose malabsorption is a possible cause of lactose intolerance, but not all people with lactose malabsorption will have symptoms of lactose intolerance, nor does it mean that drinking a little milk will cause diarrhea.

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In fact, most people with lactose malabsorption can tolerate 12g of lactose, which is equivalent to a cup of milk of about 250 ml. Secondly, due to the use of advanced detection technology, this data has been magnified to a certain extent. In the Lancet study, advanced testing technologies such as hydrogen breath test, lactose tolerance test, and genetic testing were used to detect lactose malabsorption. These detection technologies are very sensitive, which will result in the detection of small lactose malabsorption. Many people with lactose malabsorption may not reach the level of lactose intolerance when drinking milk, but they are counted in the study, which will cause this data to be magnified to a certain extent. In addition, it is not only Chinese who have a lot of lactose malabsorption. According to the Lancet study, 68% of people worldwide have lactose malabsorption. China is indeed higher, but it is not the only one. For example, South Korea 100%, Mongolia 88%, Vietnam 98%, Thailand 84%. Even in Europe, there are many countries with a high rate of lactose malabsorption, such as Armenia 98%, Czech Republic 81%, Italy 71%, Czech Republic 81%, Russia 61%. It can be seen that lactose malabsorption is quite common among people all over the world, so we don't need to belittle ourselves and think that we cannot drink milk.

Lactose Malabsorption Is an Evolutionary Selection

So why do so many people have lactose malabsorption and lactose intolerance? This is a choice of genetic evolution. Humans are mammals. Mammals produce milk after pregnancy and childbirth. The human body can secrete lactase during infancy, and infants can digest lactose and grow normally by eating breast milk. However, after growing to a certain stage, the human body will gradually reduce the secretion of lactase. The vast majority of people do not secrete lactase after adulthood, and only a few can continue to secrete lactase. The incidence of lactase deficiency in 3-year-old children in my country is 30%-40%, and it rises to more than 70% at the age of 5. This is the need for mammals to reproduce themselves, because milk is limited, and priority should be given to newborn babies. Only by ensuring that newborn babies have enough milk and grow up healthily can the continuation of the species be guaranteed.

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Therefore, from an evolutionary perspective, lactose intolerance is a good thing, a good gene. If it weren't for this gene, humans might have become extinct long ago. Therefore, even if you are lactose intolerant, don't worry, let alone consume yourself, because you are the normal majority. People who cannot continuously secrete lactase carry the lactase non-persistence gene in their bodies. About 10,000 years ago in Europe and Northern Europe, some people in the Nordic region had a gene mutation that produced the lactase persistence gene. They could continue to secrete lactase after adulthood, so they would not be lactose intolerant. These people later spread around the world with the migration and colonization of European humans. They are currently mainly distributed in Northern Europe, North America, Oceania and other places, so the proportion of people in these countries with lactose intolerance is relatively low.

How to drink milk if you are lactose intolerant?

Dairy products are rich in calcium and high-quality protein. At present, dietary guidelines of countries around the world recommend that everyone drink milk every day. The Chinese Residents' Dietary Guidelines recommend that we consume 300-500 grams of dairy products every day. So, can lactose intolerance drink milk? How to ensure the intake of dairy products? In fact, even if there is lactose malabsorption or even symptoms of lactose intolerance, there is no need to blindly avoid milk and dairy products. You can do this: First, drink a small amount multiple times and gradually increase the amount. You can drink a few sips at the beginning, then half a cup, a small cup, and drink slowly. By consuming milk and dairy products in small amounts and multiple times, your gastrointestinal tract can adapt, and it can also improve our lactose digestion ability and improve lactose intolerance. Second, with other foods, for example, when making egg custard, adding some milk can increase the intake of dairy products, and can also avoid people who don't like to drink milk from not accepting it. It turns out that many elderly people don't like the smell of milk and don't drink milk. In addition, when making steamed buns, you can also put some milk.

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Third, you can choose low-lactose dairy products, such as low-lactose milk and lactose-free milk. Lactose-free milk is now available on the market. Fourth, eat yogurt and cheese. There are many kinds of dairy products, and you don’t have to just focus on drinking milk. Eating yogurt and cheese are also good choices. Fermented dairy products such as yogurt and cheese have no lactose after fermentation. You should know that Americans consume more than ten times more dairy products than we do, and a large part of them are yogurt and cheese. So you might as well eat more yogurt and cheese.

Looking in the mirror of rumors

Some information will be misinterpreted and misattributed during the dissemination process. This is a typical rumor caused by deviation during the dissemination process. This also reminds everyone that when it comes to online information, you must pay attention to the source of the information. If you can check the first-hand information, try not to listen to the second-hand information.

References

[1] Storhaug CL, Fosse SK, Fadnes LT. Country, regional, and global estimates for lactosemalabsorption in adults: a systematic review and meta-analysis. Lancet Gastroenterol Hepatol. 2017 Oct;2(10):738-746. doi: 10.1016/S2468-1253(17)30154-1. Epub 2017 Jul 7. PMID: 28690131.

[2] Chen Jian, Sai Xiaoyong. Research progress on lactose intolerance[J]. Chinese Journal of Epidemiology, 2016, 37(2): 299-302. DOI: 10.3760/cma.j.issn.0254-6450.2016.02.030.

[3] Suchy FJ, Brannon PM, Carpenter TO, Fernandez JR, Gilsanz V, Gould JB, Hall K, Hui SL, Lupton J, Mennella J, Miller NJ, Osganian SK, Sellmeyer DE, Wolf MA. National Institutes of HealthConsensus Development Conference: lactose intolerance and health. Ann Intern Med. 2010 Jun 15;152(12):792-6. doi: 10.7326/0003-4819-152-12-201006150-00248. Epub 2010 Apr 19. PMID: 20404261.

[4] Robayo-Torres CC, Nichols B L. Molecular differentiation of congenital lactase deficiency from adult-type hypolactasia[J]. Nutrition reviews, 2007, 65(2): 95-98.

[5] Liu Qing, Jin Xueyuan, Li Jinsong, et al. Study on the occurrence of lactose malabsorption in children using hydrogen breath test[J]. Chinese Journal of Clinical Nutrition, 1996 (1): 32-34.

[6] Swallow DM. Genetics of lactase persistence and lactose intolerance. Annu Rev Genet. 2003;37:197-219. doi: 10.1146/annurev.genet.37.110801.143820. PMID: 14616060.

[7] Itan Y, Powell A, Beaumont MA, et al. The origins of lactase persistence in Europe[J]. PLoS Comput Biol, 2009, 5(8): e1000491.

[8] Curry A. Archeology: The milk revolution. Nature. 2013 Aug 1;500(7460):20-2. doi: 10.1038/500020a. PMID: 23903732.

Author: Ruan Guangfeng, Deputy Director of Kexin Food and Health Information Exchange Center

Review丨Zhang Yu, researcher at the Chinese Center for Disease Control and Prevention, national health science expert