Amanda
Rich in Calcium and proteins, milk is a great combination of good taste and nutrients for many people. However, some people have an opposite opinion, saying that drinking milk can cause them to suffer from gastrointestinal discomfort and in some cases, diarrhoea! !This phenomenon is called “lactose intolerance”. Experts estimate that about 68% of the world's population has lactose intolerance, but more than a half of them are in Asia and Africa. What exactly makes milk a “laxative”? And why are most lactose intolerant people Asians and Africans?
Q1
什么是乳糖不耐受？
What is lactose intolerance？
乳糖是一种双糖，需要特定的酶去消化，然而乳糖酶就正好是这种特殊的酶，它是从小肠里分泌的。在一个普通人的身体里，乳糖酶的数量足以消化体内的乳糖从而使它转换成为半乳糖和葡萄糖，这些元素可以为我们身体活动提供能量和营养。但对于那些乳糖不耐受的人们来说，小肠所分泌的乳糖酶并不足够去完全消化日常饮食中含有的乳糖，比如牛奶，芝士还有冰淇淋。这些未消化的乳糖会流动到大肠内，大肠内壁的细菌将会把它们分解开，并产生液体和氢气，这些就是导致腹胀，腹泻，疼痛和其他症状的元凶。
Lactose is a kind of disaccharide which needs a specific enzyme to digest, while lactase is that special enzyme, it is secreted from the small intestine. In a normal person's body, the amount of lactase is enough to break down the lactose to produce galactose and glucose that provide energy and nutrients for our body itself. However, for those people who are suffering with lactose intolerance, the small intestine doesn’t produce enough lactase to digest all of the lactose in the dairy products such as milk, cheese and ice cream. The undigested lactose moves into the large intestine(colon), the bacteria inside will break it down, but it will create fluid and hydrogen gases which lead to bloating, diarrhoea, pain and other symptoms.
Q2
Symptoms of lactose intolerance
If people are lactose intolerant, then any lactose-related products they consume may cause several adverse reactions…
1.Diarrhoea
2.Bloating
3.Stomach cramps
Those symptoms may appear from 30 minutes to 2 hours after having dairy products.
Q3
How can we get necessary nutrients
if we are lactose intolerant
(How we treat lactose intolerance)？
Milk is an important source of Calcium and Vitamin D which are used for building strong bones and teeth, ensuring blood clots and also regulating muscle contractions. But if lactose intolerant people couldn’t have any milk which means that they lost a good amount of Ca and VD from this, how do they get enough of essential nutrients to help the operation of their body? The following are some solutions to this.
Try to get Calcium and Vitamin D from other sources such as tofu, soya beans, leafy green vegetables and nuts. Those foods can also provide us with a range of other nutrients.
Lactose free milk. This process is called enzyme immobilisation. Firstly, enzyme(lactase) is immobilised in alginate beads, they are placed inside a which milk can pass through. The milk is collected and recirculated until all lactose is converted into galactose and glucose. The remaining content is the lactose free milk. This is a cheaper and more efficient process which makes lactose free milk.
Q4
Why Asians and Africans?
Many Asians and Africans, up to 70% of the population become lactose intolerant after the early childhood years. A nearly opposite proportion of lactose intolerance people in Europe area as they can directly digest lactose throughout adulthood. Why does the difference occur?
According to the analysis of the DNA of 94 ancient skeletons in Russia and Europe, the maturation of lactose tolerance appeared about 4300 years ago and spreaded throughout the Europe population. This caused natural selection to occur.
European people who can digest lactose well were more likely to survive and pass their genes to their offspring, including those for lactose digestion. But for those people who were not in Europe but living in Asia and Africa didn’t contain lactose tolerance genes, so they experienced diarrhoea, malabsorption to other important nutrients. Therefore, they were more susceptible to disease and earlier death. Thus reduced the chance to establish a lactose-intolerance family. Those families who survived were European, so it is less common that lactose-tolerance genes appeared in Asia and Africa. That’s why most Asians and Africans are lactose intolerant.
In conclusion, lactose intolerance is caused by a reduction in the enzyme lactase, which results in our inability to fully digest lactose in our daily diet. This can lead to abdominal pain, dizziness and even diarrhoea. There is no complete solution to solve this problem. But we can try to change our eating habits to get more nutrients in our bodies.
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