Among the thousands of human foods, milk should be the “closest to perfect food” for us humans. The nutrients in milk can be said to be close to 100% and can be absorbed by the body.
First of all, milk is rich in high quality of protein, which contains a complete range of amino acids, a sufficient number, and a suitable ratio. It is the most suitable protein for human tissue organization; and the protein in milk is mainly composed of casein and whey protein, which is easy to digest and absorb. Therefore, milk is an excellent source of quality protein.
At present, a considerable number of people do not drink milk because of abdominal distension, abdominal pain, exhaust, diarrhea in babies, and other symptoms after drinking milk. These symptoms are called lactose intolerance and are caused by the lack of lactase in the body, which prevents lactose from being properly decomposed and digested.
After the lactose in the milk enters the small intestine, it should be broken down into monosaccharides and absorbed by the action of lactase. However, due to the lack of lactase, lactose can not be completely decomposed and absorbed to produce the above symptoms.
Lactose is the main carbohydrate in milk. After lactose enters the body, it is broken down into glucose and galactose by small intestinal lactase. Galactose is an essential substance for infant brain development, which is closely related to the rapid growth of the baby's brain. Lactose is in the intestine. The lactic acid produced by fermentation can increase the absorption and utilization of calcium, phosphorus, potassium, iron and other minerals in food. After weaning, the lactase decreases with age and eventually becomes lactase deficiency and leads to lactose intolerance.
According to statistics, about 90% of adults in China have varying degrees of lactose intolerance. This phenomenon is related to the genetics caused by the different dietary habits we have formed for generations.
In a strict sense, lactose intolerance does not count as a disease. When we were still babies, the main source was breast milk, so at that time our body secreted enough lactase (excluding congenital lactose intolerance). When we grow up, the amount of lactase is gradually reduced because we don't drink milk often.
Research data show that the rate of this lactase reduction is 80-100% in Asia, 70-95% in Africa, 15-80% in the US, and 15-70% in Europe.
Since the activity of lactase is affected by many factors, the degree of lactose intolerance varies from person to person. However, in general, the lactase in most people's bodies does not completely disappear.
Researchers believe that the persistence of lactase is a phenomenon of co-evolution of human genes, cultures, and diets:
The lactase activity of a person in adulthood depends on the polymorphism of the MCM6 locus in his body. Its sites are mainly divided into three types:
• T/T: People with this type of gene show lactose tolerance
• C/T: People with this type of gene show lactose tolerance
• C/C: People with this type of gene show lactose intolerance
People with the first two loci, the lactase-regulated gene is like a never-extinguishing electric lamp, which has been promoting lactase activity and is not controlled by age.
The person with the C/C gene locus seems to be a "switch" electric light, which will be turned off after a certain period, and the lactase is inactivated. And this time generally indicates: we need to enter the weaning stage.
From the perspective of genes, scientists believe that lactose intolerance is the result of animals playing the genetic probabilities of their genes. This point is fully explained in Robert Trivers's theory of "parent-child conflict", which holds that the mother's breastfeeding diet after birth will bring benefits to both sides. The mother's interest is that her genes can continue in the baby. And the baby can take the nutrients from the breast milk daily.
But as time goes on, the benefits of feeding the baby to the mother will gradually diminish, such as: unable to breed new children, foraging or discovering the enemy. Similarly, babies who depend on mothers for feeding can't survive better because they can't be independent. Therefore, choosing to wean at the right time can effectively resolve this conflict. After weaning, individuals will gradually replace breast milk with other foods. The presence or absence of lactase is less important. Over time, humans have evolved a switch that controls lactase activity, the C/C locus.
In China, 80-100% of the MCM6 genes belong to the C/C type. From a genetic point of view, most Chinese are lactose intolerant. However, whether in Europe, Africa or Asia, hominids are lactose intolerant.
But why are Europeans currently far more lactose tolerant than Chinese? This is gradually evolved from the long history of milk drinking.
In the 1970s, some ceramic fragments covered with small holes were unearthed in Poland until the scientists inspected them in 2011. This discovery once again proves the development and settlement of dairy products on the European continent. The far-reaching impact.
In the Middle East about 11,000 years ago, cattle-raiser began to use fermented milk to make cheese and yogurt. Because of the small lactose content of these dairy products, humans gradually began to adapt to dairy products and chose to drink milk directly. Thousands of years later, people on the European continent regained the ability to produce lactase and drink milk. Milk has become a new source of nutrition, helping them survive the bad harvest. This is why most people in Europe have higher lactose tolerance than people in other parts of the world.
When our ancestors moved into Asia, the fertile environment of the two rivers laid a solid foundation for our lives. The diet structure of the farming society is mainly based on grain, fruits, and vegetables.
Although the Shang Dynasty was more than 3,000 years ago, people learned to drink milk. However, most of the dairy products can only be enjoyed by the nobility. Even though the Ming Dynasty entered the life of ordinary people, it was only used as a food embellishment, not an indispensable source of important nutrients, and most of them were cheese. Yogurt and other forms of lactose are less common.
Therefore, we have not experienced genetic mutations caused by nomadic life. It is a matter of more than 20 years since the Chinese began to drink milk universally. With the development of the economy and the increase in dairy production, we are qualified to drink milk anytime and anywhere. Amount of milk material.
Partly from the public number 3HFIT subscription number (ID: SH3hfit)