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  • Thanks to Brilliant for supporting this whole week of SciShow!

    今週の SciShowはBrilliant の提供でお届けしています!

  • Go to to learn more.

    詳しくは、 からチェックしてください。

  • There's a widespread belief that caffeinated drinks will make you dehydrated because the caffeine itself makes you pee.


  • But is caffeine really a diuretic?


  • Technically, yes. But it's not affecting you as much as you might think.


  • You might find you need to pee after your morning coffee.


  • But you may also need to pee after drinking a similar amount of water.


  • Still, is the caffeine making you pee more?


  • It may seem like this would be easy to figure out.


  • You just need to know how much liquid goes in and how much comes out, right?


  • Actually, it's trickier than that.


  • First of all, people vary a lot in how much liquid they take in, and in how much they pee out.


  • So rather than giving some test subjects coffee and others water, it's best to measure the same people on different days, plus or minus caffeine.

    ですから、被験者にはコーヒーとその他の飲み物を与えて調べるのではなくて、同じ人たちに異なる日ごとにカフェインの有る無しの条件で調べてみるのが 1 番の方法です。

  • And it may matter when you take a measurement.


  • Kidney output changes with sleep-wake cycles.


  • They slow way down overnight, then crank up again during the day.


  • So it's probably a good idea to monitor subjects over at least a 24 hour period.

    ですから被験者は 24 時間にわたってモニターをしていくのがいいでしょう。

  • Plus, we don't know exactly how much liquid a person needs in a day, it depends on who they are and what they're doing.

    加えて、その人が 1 日にどれくらいの水分を必要とするかも確かではありません。どんな生活を送っているかによって変わってくるからです。

  • Which makes a difference when you're monitoring them for hydration.


  • How much water we lose can also change, based on things like how much we exercise or the temperature outside.


  • You can get around some of this by establishing a baseline fluid intake level for each subject, and making sure they do basically the same things on their caffeine and non-caffeine days.


  • So it's actually quite a challenge to design an experiment that really demonstrates people are gaining or losing water.


  • That said, researchers over the years have attempted it, just not always successfully.


  • The idea that caffeine makes you dehydrated dates back at least several decades, possibly to a study from 1928.


  • This study wasn't ideal, since it included just three subjects, and the only measure was urine output.


  • I don't know about you, but I'm not going to quit drinking caffeine based on ninety-year-old data from three dudes.

    皆さんはどうか分かりませんけど、ボクは 3 人だけで 90 年も前に行われたデータを信じてコーヒー飲むのをやめようとは思いません。

  • Lucky for all of us, plenty more studies have been done since then, looking at the effects of everything from caffeine pills to energy drinks to coffee.


  • When you look at all the data together, some trends emerge.


  • A moderate amount of caffeine, in the neighborhood of 300 to 500 milligrams, does not seem to lead to water loss in most studies.

    適度のカフェイン、およそ 300~500 ミリグラム程度ですと、ほとんどの研究において脱水症状効果は見られませんでした。

  • That's the equivalent of 2 to 3 cups of barista-brewed coffee, or 6 cups of tea, or more than 2.5 liters of cola.

    この量はバリスタが淹れるコーヒーの 2~3 杯分、お茶だと 6 杯分、またはコーラ 2.5 リットル分に相当し、

  • When you go above those amounts, caffeine can have a minor diuretic effect.


  • But, as even those researchers back in 1928 recognized, if you have caffeine every day, you quickly become resistant to its dehydrating effects.

    いずれにしろ、毎日カフェインを摂取していれば体が脱水症状効果に対して耐性が付いてくるというのは、例の 1928 年の研究者たちも分かっていました。

  • In one 1997 study, the diuretic effect of even a relatively high dose of caffeine also disappeared when the subjects were exercising.

    1997 年のある研究では、カフェインを比較的多く摂取した際の利尿作用効果も、運動をしている場合には見られなくなるとしています。

  • This myth has a surprising amount of staying power.


  • It's everywhere, and even some medical professionals continue to spread outdated guidelines.


  • But take comfort.


  • The research is clear: drinking a few servings of coffee, tea, or caffeinated soda will not make you dehydrated.


  • There may be other reasons to stay away from sugary, caffeinated drinks, but hydration isn't one of them.


  • If you've got a caffeine buzz going from this high-energy episode, and you're wondering what to do next, you could keep your learning streak going with a course on

    この情報満載のエピソードをご覧になって、カフェイン摂取したようにハイになって、他にももっと観たいと思った方は のコースを試してみてください。

  • Brilliant has courses that can help you hone your math and science skills.

    Brilliant では数学と科学のスキルを上達させるためのコースがたくさん揃っています。

  • They're hands-on, interactive, and illustrated to help you pick up even their advanced topics.


  • With Brilliant, you'll be learning multivariable calculus in no time.

    Brilliant を使えば、多変数微分積分学もあっという間に学ぶことができます。

  • And the first 200 people to sign up at will get 20% off an annual Premium subscription to

    しかも、 に登録する先着 200 人には、 の年間プレミアム定期購読を 20 %オフで提供させていただきます。

  • And supporting them supports us too, so thanks for checking them out. をサポートすることが、そのまま私たちをサポートすることにつながりますので、是非チェックしてみてください。

Thanks to Brilliant for supporting this whole week of SciShow!

今週の SciShowはBrilliant の提供でお届けしています!

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B2 中上級 日本語 カフェイン brilliant 脱水 org 水分 症状

カフェインで脱水症状になる!? (Should You Worry About Caffeine Dehydrating You?)

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    Sophie に公開 2019 年 07 月 09 日