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Lactose intolerance and genetics
Spoken text of the video
Section 1: Intro
Chapter 47. Lactose intolerance and genetics. This is a specific training for the Lactose Sensor, meaning lactose intolerance. You will find this test here. This is where the Lactose Sensor is. It is part of the Gastrointestinal Sensor. It has two functions. It does not actually help you in prevention because there is no way to prevent getting the disorder, but it helps you in early detection as it takes around five years for a person to get the right diagnosis once the first symptoms arise and it helps in improved treatment.
Section 2: Lactose Intolerance
Lactose intolerance is actually quite an interesting case of a genetic disease. Let me explain to you why. Let us say that a baby during the Stone Age drinks lactose, milk, it cannot actually digest lactose itself in the way it is ingested. First, it needs to be split up into two smaller parts. For that, the baby would need the lactase gene. This gene produces an enzyme, a kind of scissors, that will split up lactose into two smaller sugars, glucose and galactose. These are just two different kinds of sugars that they come attached to each other and the enzyme just beaks them down into smaller pieces. These pieces can then be absorbed and used as energy sources. So, the little cave baby can use lactose as an energy source from his mother’s milk.
Nature is very energy-consuming. If we take a cow for example, it will, as a baby, have access to its mother’s milk but it will not have access to milk once it has grown up because cows do not have access to milk when they are adults. So, nature has developed and evolved a system where there is a genetic element that turns off the lactase gene once the baby has become a few years older, just because the body should conserve the energy of producing this enzyme because it is not required later on in life. What happens? As the cave baby grows up, it will no longer produce the enzyme. This is usually not a problem because the cave man does not have access to milk anyhow.
However, now we are in a modern age where we have cow or domesticated animal milk available to us in the fridge. Now, what happens if we drink lactose? Lactose is not broken down because we lack the enzyme. Then, bacteria uses lactose as an energy source. It starts to grow and it converts lactose in all sorts of acids and waste products. It is these waste products that actually cause digestive problems in a lactose intolerant. So, what happens in people with this genetic element is that they produce the enzyme at a high level during the first six years and then the enzyme’s production starts to decline. It declines faster in some people and slower in other people. In one of six people, the enzyme is gradually turned off. Once you have reached this level here of moderate or severe symptoms, you are considered to be lactose intolerant. This is very different from one person to the next. Some people develop it at the age of 10, others at the age of 70. There is a big variation. However, it is the same process in most people with this genetic variation.
There is a genetic mutation in this genetic element that is responsible for switching it off with increasing age. This is the SNIP. In case you do not know what a SNIP is, SNP, please do watch the general genetic training video that will explain to you how these things arise and how they originate. So, this SNIP, this genetic variation, disables the turning off of the gene with increasing age. What happens, even in adult cave men, so to speak? The enzyme is still produced. If lactose is ingested, it can still be broken down and absorbed. In 5 out of 6 people, the lactase enzyme is constantly produced. So, the question is: if this here is the mutation and this is the normal case, why do only 20 % belong to the normal case and 80 % have the mutation. This is actually a very interesting story.
It is estimated that around 10 thousand years ago in the north of Europe humans have already colonized Europe. In the region around Sweden, a single mutation happened. This genetic variation originated in one person. Suddenly, he was the very first person who was able to drink cow or domesticated animals’ milk without having digestive problems. He was the first person not to be lactose intolerant. Around that time, they already had domesticated animals that they could eat their meat but they could not drink their milk because of digestive problems. That was a very harsh time and many people died of famine. They starved to death and this one person had a huge advantage against all of the others because he was the first person to have an additional food source, which was the milk of domesticated animals. He or she, I have to say, would have then children with the same genetic variation and they also had this advantage.
So, they started to repopulate Europe with this survival advantage compared to everybody else. This was such a big advantage at this time that 80 % of all Europeans are directly related to this one person. This led to 80 % of people with European ancestry to be lactose tolerant. They have inherited the mutation while around 20 % have not inherited it and they cannot drink milk. So, this happened in only Europe. There are some other smaller cases where there is something similar happened, but it happened mostly in Europe. The Europeans were quite good in colonizing the rest of the world, so they have carried this lactose tolerance with them. However, people with African, Asian or Native American ancestry are all lactose intolerant, with some very few exceptions.
Section 3: Types of Lactose intolerance
There are a number of different forms of lactose intolerance. The type that I have just explained is primary lactose intolerance. It affects 20 % of people. Actually, it is not really a genetic variation but it is a normal case as I have said. It affects around 20 % of people with European ancestry and around 100 % of people with African, Asian or Native American ancestry. It occurs with increasing age. So, when you have this genetic variant, it means that with a very high likelihood of more than 95 % during the course of your life you will develop symptoms of lactose intolerance, but it could happen at the age of 80 or at the age of 10. This is still very variable.
Primary lactose intolerance is the most common food intolerance and it occurs with increasing age. There is the secondary lactose intolerance. This happens due to either some diseases or some damage done to the intestine. The intestine is just too damaged to digest lactose. This is usually not genetic. We call it acquired lactose intolerance. Through some other factors, it has been acquired during the course of life. Then, there is congenital lactose intolerance. This is a very rare disorder. It is actually a mutation in the lactase gene. The gene is broken. It is inactive right from birth. It is a very severe thing for babies who need immediately to switch to milk without lactose. It is very rare, it occurs right after birth. Then, there is milk protein allergy. This is actually the most common problem that babies have with milk. It is not actually lactose intolerance, it has nothing to do with lactose, it is just some protein that the immune system recognizes and attacks as an invading organism.
Section 4: The test
So, if you are to recommend a lactose intolerance test to a person, it depends on what age they are. If they are older than the age of 5, then the most useful test will be the Lactose Sensor, where we do the genetic test for the genetic variation causing primary lactose intolerance. Secondary lactose intolerance is the acquired type. It is still very rare. In this case, you run the genetic test because it is acquired. It has developed throughout life. They would do a standard breath test. Basically, you go to a hospital and have doctor do that. You get a glass of lactose to drink and then measure the amount of hydrogen gas produced because bacteria in the intestine produces hydrogen gas. You always feel you are very ill, it is a drawback but that is the way to measure this. As I said, this is very rare type of lactose intolerance. 99 % of the time it will be primary lactose intolerance in adults that is causing symptoms.
Then, there is milk allergy. In theory, this is active throughout life but mostly it is in babies. We can test it through the allergy sensor test that we have. It is not a genetic test but we actually test for the antibodies against milk protein. So, this is the most common problem in newborn babies under the age of 5. Then, there is the congenital lactose intolerance, which occurs right after birth. This is included in the baby sensor genetic test. So, we have a test for the baby sensor, the allergy sensor from 1 to 5 and the lactose sensor which is just the most common type with increasing age.
This is the end of chapter 47, lactose intolerance and genetics, a specific training for the lactose sensor.