• Question: Why do onios make you cry?

    Asked by nuckles to Betul, Bridget, Ceri-Wyn, Maria on 24 Jun 2010 in Categories: .
    • Photo: Maria Pawlowska

      Maria Pawlowska answered on 24 Jun 2010:

      Because of the substances in it that are supposed to deter animals from eating them. It failed with us because we eat the onion for it’s taste but it still can make our eyes tear up!

    • Photo: Bridget Waller

      Bridget Waller answered on 24 Jun 2010:

      There are chemicals in the flesh of the onion become toxic when they hit the wetness of eyes, and make them sting! There is a chemical reaction that causes sulphuric acid to form! It is probably the plants mechanism to stop us eating it…but then we learned how to cook to break the chemicals down. Saying that, chimpanzees are quite happy to chomp on raw onions and don’t seem bothered by them at all!

    • Photo: Ceri-Wyn Thomas

      Ceri-Wyn Thomas answered on 24 Jun 2010:

      Onions contain a chemical that gets released when you cut them and when this chemical reaches your eyes it activates your sensory neurons creating a stinging sensation. The tear ducts tear in response to this chemical.

      This chemical is attracted to water, such as the film of water covering your eyes. So if you cover the onions in water first, or stick your tongue out, most of the chemical will be absorbed here, so there will be less to go in your eyes. Try it and see if you cry less next time.

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