Why Do Onions Make You Cry?

Why Do Onions Make You Cry? The Expert Opinion

170 countries across the globe grow onions, totalling around 9.2 million acres of onions harvested annually. Onions are packed full of goodness: crammed with vitamins, minerals and antioxidants, the onion is also very low in calories. The onion forms the basis of most culinary dishes in a multitude of different cuisines around the world.

Everyone from expert chefs to culinary novices know that onions can make you cry. An expert from the Texas A&M College of Medicine has explained why onions bring a tear to your eye.

He says that the reason why onions make your eyes water starts from underground. Onions are grown underground, amongst the creepy crawlies beneath the surface who are on the hunt for something to eat. Onions have evolved with a special way of protecting themselves from being consumed.

The sulphur in the ground combines with the growing onions and creates amino acid sulphoxides; these are sulphur compounds that are easily turned into gas. When an onion is opened, the sulphoxides and onion enzymes are released: creating a sulphenic acid. This sulphenic acid and onion enzymes react and create a syn-propanethial-S-oxide gas. This gas makes the human eye tear, and also deters animals away from the onion. Sweet onions, green onions and spring onions have less of the enzyme, hence why they don’t make you cry as much, or at all.

Onions & Our Eyes

Our eyes are very sensitive, protecting one of our most important senses of our bodies. It is quite remarkable that they have a defence system to harmful gases. Our eyes contain a set of nerves that detect potential harm and react by trying to flush out the gas with tears.

In actual fact our eyes are over reacting, the gases produced from chopped onions are more of a nuisance than harm. The gas would not cause more than irritation, and has no known long-term effects. The sensation is temporary, and would not worsen any other pre-existing eye condition.

Some people are more effected by the gas onions release than others. Some people do not tear up when chopping an onion, whilst others may feel the effects from the other side of the room.

How to Avoid the Onion Tears

Preventing the gas entering your eyes will obviously stop the gas reacting with your eyes, you could wear goggles.

Some people cut onions in a bowl of water. Some people use eye drops to help lubricate the eye and dilute the gas exposure.

Other handy tricks include cutting the onion under an extraction vent, that will remove the gases before they hit your eyes. Another sworn by trick is to freeze the onion for 15 minutes before chopping, which inhibits the onion releasing the gases.

There has even been discussions about genetically modifying onions to remove the alliinase enzyme that causes the tears.

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