Onions offer great health benefits, but unfortunately, cutting them up will leave you in tears. Maybe you’ve been cutting onions your whole life and just never thought about the real reason behind why you tear up.
First and foremost, when onions are growing in soil, they use sulfur in the soil to create amino acid sulfoxides, which are sulfur compounds that readily turn into gas. When you cut open an onion, this gas is released into the air.
It’s important that onions create this gas because they grow underground, so it deters critters from eating them. Think of it as a self-protection mechanism.
Unfortunately, the same gas that deters other critters from eating them is the same gas that makes you cry when trying to eat them.
Ophthalmologist Dr. Robert Rosa Jr. explained, “It really is a complicated chemical process that creates the gas. They all act as precursors that create the lachrymatory processor—or what makes you tear up.”
Onions with the highest concentration of gas to cause crying include white, yellow, and red onions. The onions with the least amount of gas include sweet onions, green onions, and scallions.
Rosa added, “Your eyes have a set of nerves that detect anything that’s potentially harmful to your eyes. Your eyes react to the gas that is formed, and your eyes try to flush it out with tears.”
Although your eyes may burn and you tear up, the gas released is generally safe for your eyes, so you don’t have to worry about long-term effects. Furthermore, cutting onions won’t worsen any pre-existing eye condition you have.
In the meantime, if the irritation of cutting onions is too much for you, there are things you can do to prevent the waterworks from occurring. This includes wearing goggles, not touching your eyes when cutting onions, cutting onions in a bowl of water, or using eye drops.
You may have heard about chewing gum as a means of preventing tears while cutting onions, but I have personally tested this theory and did not experience any relief whatsoever.
Lastly, there are kitchen tools that help you chop onions by covering the onion, which prevents the gases from being released. These items are relatively cheap and can be picked up at your local kitchen store.