乳糖不耐受Lactose Intolerance

Intro

牛奶富含钙元素和蛋白质，对与多数人来说是一个完美的美味以及营养的结合体，但有些人却持有完全相反的意见，她们说喝牛奶会让他们患有胃肠道不适，严重的甚至还有腹泻!!这就是我们所说的“乳糖不耐受”。

专家估计全世界大约有68%人口患有乳糖不耐受，其中多于一半的人都是亚洲和非洲人。

到底是什么原因导致牛奶成为“泻药”?以及为什么大多数乳糖不耐受的人是亚洲人和非洲人?

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

乳糖不耐受的症状

Symptoms of lactose intolerance

如果你们患有乳糖不耐受，那么使用任何与乳糖相关的产品就有可能引起以下的一些不良反应...

1.腹泻

2. 胀气

3. 胃痉挛

这些症状将会在食用乳糖产品后的三十分钟至两小时内出现。

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

如果患有乳糖不耐受，如何获取必须的营养呢?

How can we get necessary nutrients

if we are lactose intolerant

(How we treat lactose intolerance)？

牛奶含有大量的钙元素和维生素D，这些元素可以帮助我们塑造强健的骨骼和牙齿，确保血液凝固，同时调节肌肉的收缩。但如果乳糖不耐受的人们不可以喝牛奶，这说明他们少了一个钙和维生素D的好源头，那他们如何得到足够的营养去运作他们的身体呢?以下有几个办法解决这个难题。

1. 食用其他的食物含有维生素D和钙元素，例如豆腐，大豆，绿叶菜还有坚果。这些食物也可以提供大量我们所需的营养。

2. 无乳糖牛奶。酶固定化会用来产生这样的牛奶。首先乳糖酶被固定在海藻酸珠中，放置在牛奶可以通过的容器里等待牛奶穿过。循环后的牛奶被收集并且再循环，直至所有的乳糖都被转换为半乳糖和葡萄糖，那么剩下的牛奶就是不含乳糖的牛奶。这是一个便宜并且有效的方法来制造无乳糖牛奶。

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

为什么多数都是亚洲和非洲人?

Why Asians and Africans?

在亚洲和非洲地区，多达70%的人再幼年时期后成为乳糖不耐受者。欧洲地区的乳糖不耐受者的比例却几乎相反，他们可以在整个成年时期都能直接消化乳糖。到底是什么原因导致这样的差异出现呢?

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?

根据对俄罗斯和欧洲的94据古代骨骼的DNA分析，乳糖耐受性的成熟出现在大约4300年前，并扩散到了整个欧洲人口。这导致了自然选择的发生。能够很好消化乳糖的欧洲人有更大的可能性生存下来，并且将它们的基因传给后代，这其中包括了乳糖耐受的基因。但对于那些不在欧洲而是生活在亚洲和非洲的人来说，他们并没有乳糖耐受性的基因，所以他们出现腹泻，这导致他们对其他的重要营养物质吸收不良。因此他们更容易受到疾病的影响并提前死亡。因此减少了建立乳糖不耐受家庭的机会。那些幸存下来的家庭大多数是欧洲人，所以乳糖耐受基因再亚洲和非洲出现的情况比较少，这就是为什么大多数亚洲和非洲人是不耐受的。

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.

总之，乳糖不耐受是由于乳糖酶的减少引起的，这导致我们不能完全消化日常饮食中乳糖。这可能会导致腹痛，头晕甚至腹泻。目前还没有完全的方案来解决这个问题，但我们可以通过改变我们的饮食习惯，让身体得到更多的营养。

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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