Why Do Onions Make Us Cry?

Written by: Khilee Gupta

Introduction

While thinking of a topic to write about, I was chopping onions for dinner and suddenly my eyes started to sting. With tears running down my face, I was questioning how such a flavorful vegetable could make me cry so much. The burning slowly started to intensify and I had to step away. That’s when I knew I had to dig deeper into this topic and find out how this is possible. Onions are a part of our daily food. They have a strong taste and a very distinctive scent. But why do they cause us to produce tears? 

Tear Factor

Prior to onions reaching the grocery stores, they absorb minerals from the soil and make food from the sun. However, onions are particularly attracted to sulphur and end up absorbing a lot of it from the soil. The sulphur then forms into amino acid sulphides. When the onions are sliced, it triggers its survival instincts releasing chemicals that travel through the air reaching the eye. As you cut it, the cells get ruptured causing a chemical reaction to occur. An enzyme called alliinase is released, which creates chemicals that are ultimately broken down into flavour molecules. The gas produced then vaporizes coming in contact with the eye. Once the eye has processed the irritation, the brain triggers a response that causes tears in order to combat the irritation. 

Are the tears harmful?

Chopping onions create a temporary discomfort for our eyes and are not considered to be harmful. Additionally, some people are more sensitive than others causing more tears as a result. However, there are ways to prevent the effect.

Solutions to avoid tears 

No one likes to cry while preparing a delicious meal, so here are some solutions to combat the irritation. 

• Using onions that contain fewer enzymes– Some onions such as the sweet onion and green onions absorb less sulphur resulting in a less invasive reaction.
• Soaking the onion- Prior to chopping, peel and soak the onion in water which breaks down the sulphur compounds.
• Freezing the onions- Storing it at a low temperature will result in the gas released less likely to vapourize.  
• Keeping the root intact- The root of the onion contains the most enzymes, by keeping the root intact fewer enzymes will be released.
• Wearing eye protection- by doing so the gas does not come in contact with the eyes.