Why do Onions Make you Cry?

For years, I wore gas permeable (hard) contact lenses, and I used to just laugh when people told me that chopping onions made them cry.  The hard contacts worked wonders for me in making sure that I never had that problem.  In my mid 30s, I stopped wearing contacts and since then I have rued the days that I doubted this fact.  Do you know why onions make you cry?Why do onions make you cry? The answer may surprise you, and it starts in the soil.

Unless you never step foot in a kitchen (or wear contact onions) you will likely have a flood of tears when you chop onions, too.  When I slice them now, even being around the onions long after I have chopped them makes my eyes water profusely.

It may surprise you to learn why onions make you cry.

Onions are part of the allium familyThis process actually starts in the soil, believe it or not.  Onions are belong to the plant genus Allium. Other members of this family are garlic, leeks, scallions and chives as well as many more similarly related plants. This family of vegetables actually absorb sulfur from the ground and helps them form molecules called amino acid sulfoxides. These sulfoxides are the reason that we have a sob fest when when onions go under the knife. When you slice an onion, you cause it to release propanethiol S-oxide (sounds awful…no wonder it has such an effect.)Sliced onions make you cry

This volatile sulfur compound releases a gas that reacts with your eyes to produce the tears.  The crying is just your body trying to wash away the irritating sulfoxide gas from the eyes.  Sometimes the tears are minor and other times it is a full on tear jerker. I have also noticed that the more finely I chop an onion, the more tears I produce.Chopped onions

You have probably noticed that cooking the onions don’t make you cry. This is because the cooking process inactivates the sulfoxide.Cooked onions in butter

There are many tips that will allow you to slice onions without crying.  My favorite one actually wastes part of the onion but works like a charm.Vidalia onions

Another thing that I have discovered is that not all onions are equal when it comes to producing tears. For me spring onions bring just a sniffle, sweeter onions bring a few tears and yellow onions are the ones that have me cursing “why do onions make you cry?”


For more cooking and home tips, be sure to visit my Household Tips Board on Pinterest.  

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