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Do Carrots Help You See Better
胡萝卜真的能改善视力吗？
You heard it over and over again from your mom.“Eat your carrots, they’ll help you see better!”
你总是听到妈妈说，“把胡萝卜吃掉，对你的视力有帮助。”
Well get ready to throw it back in mom’s face,with science!
做好准备，用科学知识反驳她。
Actually before we get to the science,let’s have a history lesson.
实际上，在开始讲解化学知识之前，我们先了解一下历史。
During world war two, British pilots had this fancy new top-secret system for spotting enemy planes called “radar”.
第二次世界大战期间，英国飞行员有一个神秘的高级机密系统，叫做“雷达”，可以观察到敌机。
No not that radar. Look it up, kids.
不，不是你所知道的那种雷达。仔细听着，孩子们。
Our chemist friend Chad Jones picks up the story from here: “This fancy new radar system gave pilots a huge advantage over their enemy.To keep this advantage a secret the British royal air force started a rumor that their pilots ate lots of carrots to help them see the enemy better at night.”
我们的化学家朋友Chad Jones为我们带来了这个故事：“这种新的雷达系统让飞行员们相对敌人有了更大的优势。为了让这种优势保密，英国皇家空军开始传达一个谣言，他们的飞行员吃很多胡萝卜，帮助他们在夜晚更清楚地看到敌人。”
Of course it wasn’t the carrots, it was just the radar, but the rumor actually stuck,and it still circulates to this day.
当然不是胡萝卜，实际上是雷达发挥作用。但是谣言确实发挥了作用，直到今天仍在流传。
And the funny thing is, there’s actually a bit of truth to it.
有趣的是，其中确实不乏真实的成分。
Carrots have in them a chemical compound called beta carotene (and…no, it’s not named after carrots).
胡萝卜中含有一种名叫β-胡萝卜素的化合物（不，这并不是以胡萝卜命名的）。
When you eat foods with beta carotene,your body converts it into vitamin A.
当你食用了含有β-胡萝卜素的食物时，你的身体将它转化为维他命A。
And that vitamin A gets turned into retinol.
维他命A随后转化为视黄醇。
Now retinal is found in your eyes inside vision cells called "rods".
现在，你的眼睛视觉细胞中可以发现视黄醇，这些视觉细胞叫做“视杆细胞”。
At the very tip of the cell you'll find retinal wrapped inside of a protein.
在这些细胞的顶端，你可以发现包裹在蛋白质中的视黄醇。
That protein is twisted and compact a little bit like this ball of yarn...
这种蛋白质是弯曲的，有点像一团纱线。
And retinal sits comfortably inside - like a baby wrapped in a tight blanket. But, when light shines on this happy, sleeping baby...It stretches out from this form (called cis) to this form (called trans).
视黄醇就舒服地包裹在这团纱线中——就像婴儿包裹在一张轻柔的毯子里。但是，当阳光照射在这个快乐熟睡的婴儿身上时，它就会从顺式伸展为反式。
This stretching unravels the protein,starting a chain reaction that leads down the rod cell, through the nerves,and to the brain letting you know it's not dark any more.
这个拉伸过程会拆解蛋白质，开始连锁反应，延伸至视杆细胞，至神经，到达大脑，让你知道现在已经不再黑暗了。
And that’s how you see light.So where does that leave our carrot myth?
这样你就看到了光。那么，为什么会有关于胡萝卜的谬论呢？
Well, any food that has vitamin A will be good for your overall eye health.
任何含有维他命A的食物都有益你的双眼健康。
That’s carrots, lettuce, spinach, mangoes,milk, cheese, cantaloupe and peas.
比如胡萝卜，生菜，菠菜，芒果，牛奶，奶酪，哈密瓜和豌豆。
But if you already have a diet of vitamin A,these foods won’t actually improve your vision.
但是如果你已经食用含有维他命A的饮食，这些食物不会改善你的视力。
So don’t forget your vitamin A,but don’t count on getting rid of your glasses any time soon just because you’re chomping on a carrot.
所以，不要忘了摄入维他命A，但是不要以为你吃了很多胡萝卜就可以很快摘下眼镜。
