Why can a mouthful of milk bring a baby back to full health? Learn more about breast milk | Ren Guangxu

As soon as we are born, we face a very important choice - to strike a balance between food, microorganisms and immunity.

How can we achieve this balance? Our mother's milk alone can solve the problem.

It basically covers all the nutrients needed by the baby during birth, and also contains some immune-related substances, which help fight microbial infections while preventing the immune system from overreacting and causing harm to the body.

On September 19, 2020, at the 25th "I am a Scientist" lecture, Ren Guangxu, an associate researcher at the Institute of Food and Nutrition Development of the Ministry of Agriculture and Rural Affairs, gave a speech entitled "What's in the milk delivered to your door every morning?"

Ren Guangxu's speech video:

The following is the transcript of Ren Guangxu’s speech:

Hello everyone, my name is Ren Guangxu, and I’m from the Food Nutrition Development Institute of the Ministry of Agriculture and Rural Affairs. This time I will mainly share with you the relationship between dairy products and health.

The story begins with breast milk and the human immune system. Before we are born, after 10 months of pregnancy, we have already become accustomed to the clean and tidy environment in our mother's womb. But this environment is broken with birth, and we are exposed to a world full of microorganisms.

This world is full of various crises: during birth, we will be squeezed by our mother in the birth canal, and the microorganisms in the birth canal will enter our body; at the same time, we will use our lungs for the first time, and breathing from the lungs will also allow microorganisms in the air to enter our body.

When a baby is born, it is thrown into a quagmire full of microorganisms - which puts great pressure on the immune system because immune cells are not challenged by microorganisms after they are secreted from the thymus.

What is the thymus? It is a military academy for training the immune system.

The immune cells have never seen these microorganisms when they are in the mother's womb, so after birth, they are exposed to the microorganisms, which is equivalent to the enemy being at the gate.

With so many microorganisms coming, what will happen to our immune system?

Without experiencing this kind of baptism on the battlefield, they must also grow up on the battlefield. So these microorganisms use the skills they learned in military academies, for example, they will secrete some gamma interferon and inflammatory cytokines.

Inflammatory cytokines will kill the microorganisms they encounter, but these immune cells are very young after all, and their main purpose is to kill all these microorganisms. They do not consider whether the battlefield is too large. This will cause a phenomenon - when they attack, they do not consider the damage to the body's tissues, which may cause inflammation of the newborn's intestines.

If the inflammatory situation is not effectively controlled, fatal neonatal enteritis may occur. This is a very serious problem. Therefore, we are faced with a very important choice as soon as we are born - to achieve a balance between food, microorganisms and immunity.

How to achieve balance?

The problem can be solved well by mother's milk alone.

First of all, food is not the most important issue for newborns, because before birth, the baby absorbs a lot of nutrients from the mother's placenta and converts them into fat that can be stored, making itself fat. This fatness is not cute, but the three-day dry food that the baby brings with him when he is born.

What is the most important question at this time?

It is to resolve the conflict between microorganisms and the immune system.

The immune system needs these microorganisms. For example, the microorganisms in the intestines can absorb some substances that the human body cannot absorb, such as dietary fiber. However, the immune system also attacks the microorganisms, which is a very contradictory system.

How to resolve this contradiction?

For babies, the same old saying applies: there is no problem that cannot be solved by a mouthful of milk. It basically covers all the nutrients that babies need during birth, and can adjust the required nutritional content according to the various stages of the baby's development.

For example, the milk secreted by the mother five days before birth is called colostrum. In fact, the nutrients in colostrum do not account for the main part. Its main components are some immune-related substances. For example, soluble antibodies can help fight pathogens in the baby's body; the mother's milk also contains a small amount of immune cells, but these immune cells come from the mother's body and are very mature. Some of them even have some memory. So when these immune cells enter the newborn's body, they help the newborn solve microbial infections that they cannot handle, just like the peacekeeping forces sent by our country.

At this point, you may ask, doesn't breast milk have to go through the stomach? There is strong hydrochloric acid in the stomach, and the pH value is very low, so why aren't these active substances killed?

In fact, nature is really amazing. It has already designed it in advance - the pH value in the stomach of a newborn is close to neutral, and the distance from their mouth to the stomach is very short, which can maximize the retention of active substances in breast milk and allow these active substances to enter the intestines of newborns to provide protection.

In addition, breast milk also contains lactoferrin, which the latest research has found can help the baby's immune system and inhibit excessive immune responses. It's like our immune system is fighting a war, and after the fight, firefighters come up to clear the scene to prevent the war from spreading too far.

Therefore, breast milk not only provides nutrition for infants in the early stages of life, but more importantly, it provides a protective effect on immune homeostasis.

Will we no longer have the protection of breast milk when we grow up?

Actually, no, because when you grow up, there are many dairy products to choose from, such as ambient temperature milk, low-temperature milk, skimmed milk, etc.

Many people may have a question: Why can room temperature milk be kept at room temperature for so long? Is there any preservative?

In fact, the reason why room temperature milk can be stored at room temperature mainly depends on the processing method of milk. When milk is just squeezed out, it contains a large number of microorganisms, which need to be eliminated through food industry technology.

There are currently two methods, one is pasteurization and the other is ultra-high temperature sterilization. Pasteurization uses a relatively low temperature to sterilize, about 72 to 85 degrees, which can kill pathogenic microorganisms while retaining a large number of beneficial or neutral microorganisms. Therefore, it has strict requirements on the storage time and storage location of dairy products.

Ultra-high temperature sterilized milk uses instant ultra-high temperature sterilization method, which basically kills all microorganisms in the milk, leaving the milk in a near-sterile state. If there is no external contamination, theoretically it can be kept for a long time, half a year or even a year.

So, which of these two types of milk should you choose?

In fact, each has its pros and cons. The biggest advantage of low-temperature milk is that it preserves many biologically active substances in milk intact. However, its storage conditions are very harsh, so this kind of milk is not suitable for long-distance travel or earthquake relief. Although room-temperature milk can solve the problem of long-term storage, many biologically active substances or nutrients in it are destroyed to some extent.

So the type of milk you choose depends on the occasion you are going to use it in. However, if you choose low-temperature milk in the supermarket, do not boil it when you get home. This will inactivate the biologically active substances in the low-temperature milk, which is equivalent to buying room-temperature milk at the price of low-temperature milk.

Our team mainly studies the nutritional content of milk and how it affects human health through gastrointestinal microorganisms after drinking it.

For example, we focus on how dairy products affect muscle health. Muscles are needed in all aspects of physiological activities. For example, there is a small muscle in the human ear, which transmits sound signals to the brain. As the elderly age, their muscles will shrink to a certain extent. If this muscle shrinks, it will cause the elderly to have difficulty hearing clearly.

Our research team hopes to perform some nutritional interventions through natural dairy products, and our first target is muscle health.

Which group of people need this kind of muscle health care the most?

Cancer patients. Because the muscles of cancer patients will be greatly depleted. Muscles contain a lot of nutrients, which are not only related to exercise, but also secrete some substances to degrade and sacrifice themselves in some emergency situations. The sacrificed products - a lot of protein, especially some high-quality protein, will be provided to other important organs of the human body to enable them to work normally.

For example, a man with very strong muscles got COVID-19, and after he recovered, his muscles were reduced to a level lower than that of a normal person. But thanks to his strong muscle protection, it would have been difficult for him to survive this period.

The photo below shows us using milk to intervene in the muscles of cancer patients. The thigh muscles of cancer patients are severely atrophied. Theoretically, this muscle should be very abundant. After two months of intervention, we have achieved a very good intervention effect. The tissue sections of the local muscles show that the distance between muscle fibers increases after the intervention.

When doing this kind of population intervention, especially milk nutrition intervention, we need to pay attention to a very important principle - the double-blind principle. The so-called double-blind principle means that the designer of the experiment and the final data collector must go through a password transfer process. What is transferred? The group information is transferred. In addition to the experimental researchers, all participants do not know what kind of dairy products they are using.

The double-blind mechanism is to avoid subjective influences from researchers or participants. For example, if I think eating this kind of food is good, I will psychologically suggest it to myself, which will affect the accuracy of the data.

I am a researcher trained in interdisciplinary fields. My undergraduate degree was in botany, and my master's and doctoral studies were mainly in the School of Basic Medicine, studying the interaction between microorganisms and immunity. After graduation, I went to the Institute of Microbiology of the Chinese Academy of Sciences to study how intestinal microorganisms regulate immune development.

In 2014, I joined the Institute of Nutrition, mainly conducting research related to dairy nutrition.

Why did I choose dairy products? Because I think dairy products, represented by milk, are actually a very attractive food system. Dairy products contain many nutrients or bioactive substances. The composition and content of these bioactive substances will fluctuate in different dairy products, so they are very diverse.

On the other hand, our research focuses on human health. Humans are very complex organisms. The genes given by their parents are different, and the composition of microorganisms in the intestines is also different. Each microorganism carries its own genes, so the genomes they make up are also different.

As an organic whole, our daily preferences for food, living habits, and moods are all different, all of which will affect many aspects of health. So this study has become a multi-factor study of multiple factors.

In the past, this kind of multi-factor research was actually very difficult because it was impossible to lock in one variable. However, with the development of science, especially the integration of interdisciplinary disciplines, it provides a good platform or method for this kind of multi-factor research. We can use multi-omics, bioinformatics, and even machine learning, and their cross-integration enables us to understand the collaborative effects of multiple systems in an unprecedented way.

Therefore, the main task or mission of our team is to enable everyone to choose dairy products that suit them according to their genetic characteristics. We also hope that everyone can enjoy the health effects of dairy products.

Asians have a characteristic called lactose intolerance. Many people want to drink milk, but because they lack a lactase in their bodies, they are prone to diarrhea after drinking milk. This also seriously affects the milk drinking experience.

What should we do? We have an idea. Intestinal microorganisms are a very important part of the human body. Among them, there are some very common probiotics. Can we let them carry lactase and make it into something similar to milk companion and put it in milk?

In this way, it will be easy for people who are lactose intolerant to drink milk, because probiotics can break down lactose, which can at least minimize the bad experience brought by milk and enjoy the nutrition it brings to humans.

Thank you everyone.

Speaker Ren Guangxu: "What's in the milk delivered to your doorstep at 7 o'clock every morning?" | Photography: VPhoto

Author: Ren Guangxu

Producer: Wu Ou

Planning: Maiya Yang

Editor: Fan Kexin

Layout: Lei Yuer

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