Why do onions make you cry? — the chemistry and health benefits of onions

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Español: Cebolla siendo cortada.

Many of us have cried over chopping onions. Do you know why they make your eyes water, though? Yes, yes, they have that pungent juice spraying up into your eyes. But do you know what’s in that misty juice? And don’t stop that chopping – chopping and crushing onions release health-benefiting compounds.

Let’s get straight to the point. The component in an onion that makes your eyes water is called lachrymatory factor, from Latin lacrima, or “tear.” (How appropriate is that!) Lachrymatory factor irritates the eyes and stimulate the tear glands to produce tears, much like the action of a tear gas. Continue reading –>

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13 Comments

Filed under Health, Q&A

13 responses to “Why do onions make you cry? — the chemistry and health benefits of onions

  1. Jeanie

    I didn’t know the mechanics behind why cutting onions make you cry, but y’know what else I didn’t know? That chopping jalapenos with your bare hands make your hands burn so, so badly afterward.

    • It burns because of capsaicin in jalapeño and TRPV channels in your skin. Maybe I can cover this topic one day, but it’s good that you’ve had a hands-on experience of it! ;) (I hope your hands have recovered from the pain, though!)

  2. [Adapted from Imai et al. (2012) Nature.]:
    The published year of the article might be 2002. Please, see: http://www.nature.com/nature/journal/v419/n6908/full/419685a.html

    • Thank you very much for the correction! The typo in the figure legend has now been corrected. Comments/suggestions that help my posts improve are greatly appreciated! :)

  3. kkj

    i thoughth onions made you cry because they have sting rays

  4. Pingback: 5 Simple Steps to Chop Onions without Tears | Health200

  5. munil singh

    plz sent me which of acid to smell in onians and gralic.,….help me

  6. thank you very much thy explaination was more clear and i get thy point……………………

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  8. Thank you, I’ve recently been looking for info about this topic for ages and yours is the best I have discovered till now. But, what in regards to the conclusion? Are you positive in regards to the source?|

  9. Clyde Herreid

    Is there an evolutionary significance to onion smell and the lachrymatory factor?
    CFH

    • That is a very interesting question, Clyde! It is said that hot chili peppers have capsaicin (stuff responsible for the hotness) which birds do not have the receptor for, so that mammals leave them alone while birds eat them and help distribute undigested seeds. (Too bad for the hot chili peppers that a lot of humans love them for the spiciness!) It is very possible that onions have adopted a similar mechanism to discourage mammals from devouring them. If I come across a more specific evidence or examples, I’ll post them for sure! Thank you for leaving a comment :)

  10. Pingback: The Chemistry of an Onion | Compound Interest