A Moment of Science

Does An Onion A Day Keep The Doctor Away?

As it turns out, the same compounds that make you cry may also keep you healthy.

Three yellow onions against a white background

Photo: SoraZG (flickr)

Onions and garlic are both types of alliums, a genus boasting some 750 different species.

Have you ever wondered why your eyes water when you chop onions?

Like Tear Gas

Despite what you might think, the smell of onions is not what makes most people cry. You see, an onion gets it distinctive taste from compounds that contain sulfur atoms. When you slice an onion, you damage its cells, triggering a chemical reaction that converts these compounds into an acid that acts like tear gas.

At the same time, the byproducts of this reaction condense to form the molecules responsible for the onion’s pungent odor. In other words, the same chemical reaction that makes you weepy also releases the onion’s smell.

Garlic And Health Benefits

A similar thing happens when you chop garlic. When it’s still in bulb form, garlic doesn’t smell like much. It’s only when you mince or dice the garlic’s cells that a chemical reaction releases the smell we associate with garlic.

However, no one cries from slicing garlic. This is because the byproducts of the chemical reaction that takes place in garlic are different from the byproducts you get when you chop an onion.

Scientists suggest that the same chemical that gives garlic and onions their distinctive smell helps them fight off bacteria and fungus and parasites. There might be something after all behind all those reports that garlic and onions are good for you.

Read More:

  • Why Do Onions Make You Cry (YouTube)
  • Exploring The Stinky Science Of Alliums (NPR)

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