喝酒容易臉紅？代謝好？為什麼你應該要少喝酒？Asian flush? Why your face turn red when you drink alcohol?
喝酒容易臉紅？為什麼你應該少喝酒？
Why your face turn red when you drink alcohol?
Disclaimer: Opinions expressed are solely my own and do not express the views or opinions of my employer.
你喝酒容易臉紅嗎？其實這是有一個名稱來描述這個現象的— Facial flush reaction。然後因為這個現象很常發生在亞洲人身上，所以又會被稱作 Asian flush 或 Asian glow。
在臺灣，常聽到很多長輩看到（或本身有）喝酒會臉紅的時候，總是會說：「這代表你的身體代謝好！酒精代謝得很快！」但事實真的是這樣的嗎？而且究竟喝酒容易臉紅，它的原因是為什麼？而這個背後可能的意義又是什麼呢？
“How Does Alcohol Cause Cancer?” Cancer Research UK - Science Blog, scienceblog.cancerresearchuk.org/2016/02/09/how-does-alcohol-cause-cancer/
也就是說，酒精進入我們體內以後，主要需要以下兩個 enzyme (酵素) 來把酒精代謝掉：
Alcohol dehydrogenase (ADH)
功能：將酒精轉換成 acetaldehyde (乙醛)
Acetaldehyde dehydrogenase (ALDH)
功能：將 acetaldehyde (乙醛) 轉換成 acetate (乙酸)
所以，一般 enzyme 正常發揮作用的人，酒精順順地進入體內後，就這樣藉由 ADH 順順地轉換成 acetaldehyde (乙醛)；再藉由 ALDH 順順地轉換成 acetate (乙酸)，然後 acetate (乙酸) 之後可以被我們的身體使用，作為一部分可能的能量來源。
但是在東亞，大約有50%的人，這些人的 ALDH 是有缺陷的 [3]。也就是說，比起正常的 ALDH，這些人的 ALDH 代謝的效率比較慢。於是，酒精代謝後的 acetaldehyde (乙醛) 就這樣慢慢累地積在身體裡，最後導致喝酒後臉紅的現象產生。不只如此，那些喝酒後所產生的噁心想吐、頭痛、還有心跳加快…等，令人不愉快的宿醉經驗，都與 acetaldehyde (乙醛) 的累積有一定的關係！
更糟糕的是，這些人同時也可能具有 ADH 的缺陷。這樣的缺陷，造成這些人的 ADH 轉換效率比其正常人要來得高，更快加速 acetaldehyde (乙醛) 的累積！
等等？效率高難道不是代表好嗎？你這是什麼意思？
來來來，我們再來看一次這張圖：
“How Does Alcohol Cause Cancer?” Cancer Research UK - Science Blog, scienceblog.cancerresearchuk.org/2016/02/09/how-does-alcohol-cause-cancer/
也就是說，本來 ALDH 已經作用緩慢的情況下，如果 ADH 的效率又比較高，會造成 acetaldehyde (乙醛) 的累積更加快速。就好像今天家裡的浴缸已經開始堵塞惹，沒想到水龍頭水流量又超英趕美，當然很快地，浴缸的水自然就越來越滿，滿到最後就漫出來惹～
所以，如果你是屬於喝酒容易臉紅的類型，可能你的 ALDH 代謝比較慢，也有可能你的 ADH 代謝真的比較快。但重點是，喝酒容易臉紅並不是一件好事，acetaldehyde (乙醛) 的累積可能會導致你的 DNA 發生修復上的錯誤或是染色體的重組（癌症發生的原因之一）。另外，ALDH 的功能缺失也和esophageal cancer (食道癌) 的發生有一定程度的相關 [4]。根據這篇紐約時報的文章，ALDH 缺陷的人，一天喝兩瓶啤酒，罹患食道癌的機率是 ALDH 正常人的六到十倍 [5]。
“An ALDH2-deficient person who has two beers a day has 6 to 10 times the risk of developing esophageal cancer as a person not deficient in the enzyme.”
同時，這篇文章的最後也指出，對亞洲成人而言，減少酒精的攝取可以顯著地降低發生此類癌症的機率。研究結果顯示，ALDH 缺陷的日本男性，若降低每週的酒精攝取量至低於九杯，可以減少約53%的食道癌細胞 (esophageal squamous cell cancers)。
“The researchers calculate that if ALDH2-deficient Japanese men reduced their weekly consumption to fewer than nine drinks, 53 percent of esophageal squamous cell cancers in that group could be prevented.”
所以，下次在黃湯下肚之前，考慮一下節制飲酒，或許會是對你的健康一個不錯的選擇！
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接下來我只是想談談關於我在找尋資料時所閱讀到的一些統計數據，主要是關於帶有 ADH 和 ALDH 基因缺陷的人，在亞洲（尤其是東亞）的比例。我覺得蠻有趣的，在這邊跟你分享，不妨你也可以看一看～
The next few things I would like to mention here is just about the prevalence of the deficient enzyme ADH and ALDH among East Asian population.
As we know, genes sort of decide what we are and who we are. Part of the reason is because our body use genes as the blueprint to produce various types of the protein. And these different kinds of proteins affect the function of our body, and furthermore determine what we are and who we are.
As for the enzyme we talked about earlier, there are also some genes encoded for these enzymes (proteins). There is a variant gene encoded for the enzyme ADH called ADH1B. On the other hand, there is also another variant gene encoded for the enzyme ADH called ADH1C. These two variant genes are believed to be responsible for the increasing rate of converting alcohol to acetaldehyde.
According to the study by Eng, Mimy Y et al., approximately 80% or more of Han Chinese, Han Taiwanese, Filipino, Japanese, Korean has this gene – ADH1B. And this gene only been found in some Chinese aborigine and Taiwanese aborigine people, and only about 15% of Indians. For the gene ADH1C, this study indicated that almost all Chinese and Korean have ADH1C which, again, result in the decreasing converting rate from acetaldehyde to acetate.
On the other hand, as for another enzyme we mentioned earlier which also contribute to the facial flush reaction – ALDH, there is also a gene encoded for this enzyme called ALDH2. This study showed that almost 50% of Chinese-American and Japanese carry this gene; and one-third of Korean, Han Chinese, and Han Taiwanese carry this gene as well.
Despite the fact that the prevalence of this gene ALDH2 is relatively high in East Asia, approximately only 12% of Mongolians and around 10% of Thai carry the gene. Furthermore, almost no Filipinos, Indians, Chinese aborigines or Taiwanese aborigines carry this gene.
Interestingly, the study, especially about the statistics, sort of explained why the Taiwanese aborigines are so good at drinking alcohol without having any adverse reactions that other Taiwanese usually suffer from when they drink huge amounts of alcohol. But again, even though you don’t have any of these deficient metabolic enzymes above, it’s always good to avoid the headache, nausea, fast heart rate and other uncomfortable experiences caused by binge drinking, not to mention if you are that kind of quick facial flush person.
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