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  • Writer's pictureK.L.

The Science Behind: Why Onions Make Us Cry

Cover: Ishita Aggarwal

Imagine a person who doesn't cry if they break their arm, at a loved one's funeral, or when their feelings are hurt. Imagine someone who doesn't cry through any of this, but cries at the sight of an onion. That's right. An onion.

How does this simple vegetable found in your dinner make you cry? I'm sure your meal isn't that bad! Perhaps there's something more.....

The Why:

To find out why onions make us cry more than a soap opera, we have to rewind time a little. Before the onions ended up on your kitchen counter, they were absorbing minerals from the soil. Onions can absorb a good amount of sulfur, one of the most reactive elements. They use this sulfur in a large number of amino acids in their cells. (Amino acids are molecules or compounds made of carbon, oxygen, nitrogen, and hydrogen.)

Now, let's get back to your kitchen. As you slice the juicy onion, you break open the cells in it and release the liquid in them. Enzymes (substances that help speed up chemical reactions) come into contact with the amino acids rich with the absorbed sulfur. When this happens, the enzymes and amino acids are rearranged into a new chemical called syn-propanethial-S-oxide. I know, it's a long name! Imagine having that on your spelling test! Anyway, this chemical vaporizes and causes a burning sensation when it meets your eyes.

In response to this, your brain frantically tries to shield your eyes from harm. To do this, it produces tears so your eyes won't be damaged. In other words, you could say that the syn-propanethial-S-oxide is a thief, trying to break into a bank (your eyes), and your tears are a security system full of lasers and other cool stuff managed by your brain, the ultimate security system.

Fun Facts:

  1. Onions are filled with sugars that boost your metabolism as well as vitamins, minerals, and dietary fibers. They're basically one of the veggies that your parents would have loved for you to consume when you were young.

2. Ancient Egyptians practically worshipped onions. They believed that they symbolized eternity.

3. Save your dog's health by NOT putting onions in their bowl. Onions can weaken a dog's blood cells, resulting in anemia.

4. To prevent the waterworks while cutting onions, make sure to slice them under running water or submerge them in water and cut them. You may not be able to fight fire with fire, but you can certainly fight water with water!

Now we know why onions make us cry. I hope you enjoyed reading this article just as much as I enjoyed writing it! If you have any questions, post them in the comments below!

Hoping your day goes tear-iffic!




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