1. Hundreds of millions of Chinese people claim to be "lactose intolerant", so should we still drink milk?

"A glass of milk a day makes Chinese people strong", I believe everyone is familiar with this sentence, but many people also say that most Chinese people are lactose intolerant, so can drinking milk still achieve the purpose of strengthening the body? In fact, this sentence itself is problematic, because it jumps directly from the inactivation of lactase to the issue of milk supplementation, which is unreasonable.

Today let’s talk about lactose intolerance and drinking milk to keep fit.

01. Why does lactose intolerance occur?

Lactose intolerance is not determined by a single SNP.

First of all: the mechanism of lactose intolerance is not completely clear at present. This is the biggest problem. Often, we see various theories describing Chinese people's lactose intolerance, and these theories are all based on a SNP (rs4988235) in the lactose metabolism gene.

Looking at this SNP alone, it seems to be true. However, it is not just this single SNP that determines lactose intolerance. Researchers have found that at least 8 or more SNPs are related to lactose intolerance, which is a common condition.

So, don't jump to conclusions.

Secondly, lactose intolerance is not a single classification, there are at least four types.

02. Does this mean I can’t drink milk if lactase is inactivated?

Today we are simply discussing genetically determined lactase inactivation. Lactase inactivation does not mean that you cannot drink milk. This is a basic truth, but many times, people equate it.

In the past, I had learned about lactose intolerance because I was very skeptical about the data and conclusions. After all, it was too counterintuitive. Humans basically rely on breast milk to survive during infancy (whey milk powder appeared very late). In this case, if a gene prevented humans from consuming breast milk, it would have been eliminated in evolution. After all, it would not even survive. This is a natural selection. Later, I found that there was a problem with my understanding here.

First, lactase is not inactivated from the beginning, but is activated during infancy. Therefore, most children have no problem with breastfeeding, and the World Health Organization also recommends breastfeeding for 6 months to 2 years.

Worldwide, the proportion of infants with congenital pure lactose intolerance is very low. For example, in Finland, where it is most common, the proportion is only one in 60,000, so most people are OK.

Lactose intolerancein infancy resulting from congenital lactase deficiency is a rare disorder. Its incidence is unknown. This condition is most common in Finland, where it affects an estimated 1 in 60,000 newborns.

The reason why this gene was turned off later is currently believed to be the result of epigenetic modification (but epigenetic modification is a rather mysterious thing and is still at a shallow level of cognition)

Second, even if lactase is shut down as the baby grows, it does not necessarily mean that related symptoms will appear. The human intestinal system has a very powerful metabolic system and tolerance.

1. Powerful metabolic capacity. It is not just the human body that can metabolize lactose. We have a powerful intestinal microbial system, which is more complex than humans. There are hundreds of types of cells in the human body, and tens of thousands of types of intestinal microorganisms; there are 4-6 billion cells in the human body, and tens of billions of intestinal microorganisms.

Intestinal microbes at this scale can easily process a little lactose. Therefore, for most adults, there is no problem at all drinking some milk. Intestinal microbes can help you process lactose. Of course, if you consume a lot of milk, such as Baoqiang:

If you are lactose intolerant, then the intestinal microorganisms metabolize a large amount of lactose, which will produce gas and cause bloating. In addition, the accumulation of lactose increases the osmotic pressure in the intestine, preventing water absorption and causing diarrhea.

2. Strong tolerance. Even if the intestinal microorganisms do not play a role, it does not mean that symptoms will occur. The human digestive system has a strong tolerance range, and only when it exceeds this range will it trigger a certain reaction. In other cases, most of them are directly treated as waste. This is a bit like the fiber metabolism of the human body. For example, some people swallow a coin, and there is no strong reaction, and it is directly treated as waste.

03. Milk is not just lactose

From the argument of lactase inactivation to the argument that drinking milk is useless, this is a typical slippery slope argument. Maybe people have a misunderstanding of the composition of milk, and people's understanding of digestion is still at the perspective of what you eat is what you excrete.

1. Lactose is only a tiny factor in milk. * Take a look at a picture of the nutritional composition of milk. You will find that milk contains more than just lactose.

In fact, the first function of milk is to replenish water, hahaha, after all, the main component of milk is water. The components of milk include protein, fat, sugar, and a large amount of minerals, such as calcium needed by the human body.

These ingredients are all present in milk, so people drink milk not simply to supplement lactose. In fact, for adults, lactose is meaningless and it is better to eat a steamed bun.

2. Even if you are lactose intolerant, it does not mean "puerperal milk". People think that lactose intolerance means not supplementing with milk. This is a digestive fallacy. Maybe the questioner thinks that lactose intolerance means "puerperal milk when drinking milk"~

However, the reality is that even if lactose intolerance occurs, only the intolerant lactose is excreted, while the beneficial ingredients can still be absorbed.

04. Let’s take a look at the definition of lactose intolerance

Finally, the definition of lactose intolerance is very interesting. Various definitions all mention "more than a certain amount", but there are many opinions on how much this amount is. Some say it is 100ml, some say it is 1L. In short, it is rare to hear that you can't drink a single sip of milk. In fact, studies have found that, for example, in Japan, where more than 90% of people are lactose intolerant, most people can still drink 200ml of milk a day without any discomfort.

Some studies have found that most Japanese can consume 200 ml (8 fl oz) of milk without severe symptoms

So, keep drinking milk, don’t let yourself feel that you are not good enough to drink milk after listening to some theories. I even suddenly thought of a classic line:

The dream here can be replaced by drinking milk:

Don't let anyone tell you that you can't drink milk. If you can drink milk, then drink it decisively. Those who can't drink milk want to tell you that you can't drink milk either, but you can, brother!

Finally, science is used to understand the world, not to replace facts. If a fact contradicts certain scientific cognition, it must be that scientific cognition is not yet perfect.