Why Do I Cry When I Cut Onions?
Why do we cry when we cut Onions?
If you have been to the kitchen ( and done some cooking of-course) you have probably experienced this at some point. You start to chop the onions, but half way into the job you experience a burning sensation in the eyes. The 'heat' is too strong you can barely open the eyes. With in seconds, they get filled with tears which eventually start rolling down your cheeks like you are weeping for loss of a dear one. The logical thing to do is abandon the knife and rush to the tap to wash out whatever is offending the eyes. Question is how does the onion on the chopping board cause so much havoc in eyes that are half a meter away?
I have heard explanations like when you cut into an onion; you break open microscopic cells filled with enzymes that turn into volatile gasses. As they escape, these gasses find their way into the moist eyes causing a chemical reaction. This reaction leads to formation of an irritant substance, which causes the burning sensation. When this substance reaches the glands in the corner of the eyes, they in turn produce tears in attempt to flush the offending chemical out. For a while, this explanation seemed sufficient until I experienced something strange.
One day (about three years ago) I was in the kitchen trying to surprise my darling with a special birthday delicacy. I got along well with all other preparation until all that was left was cutting the dreaded onion. I got my knife and asked the man in me to be brave. " its just an onion." I said to my self. I placed it on the chopping board as usual and started going at it. Half way into it, all was well. I completely chopped it to very small bits but got no 'fire' in the eyes. "This should be a special onion," I thought to my self. I got into the second one and the story was the same. I started thinking may be my darling's birth day is indeed a special day. One fact was eluding my mind at the time. I was having a common cold I had picked up three days earlier. Subsequent days in the kitchen were the usual crying story.
It has been three years now and I must say I do a considerable amount of cooking, but I can almost swear that every time I cut an onion when my nose is stuffed from having a cold, I never cry or experience the burning in my eyes. Does blocking the nose prevent the havoc created by cutting onions? The answer is yes because I have tried it and it works. I implore you to try it. What I do these days is to keep my nose as far from the onion as I can. At times I simply hold my breath, and the magic is worked. My trouble now is to figure out how exactly this works. Could it be that the volatile gasses that come out of the onion travel through the nose as we inhale and into the eyes rather than directly into the eyes?
I have been made to understand that there is indeed a connection between the eyes and the nose. That in fact; after tears have served their purpose in the eyes, they travel to the nose through an anatomical passage. This passage is also called the lacrimal drainage system. This drainage system is assisted by an active lacrimal pump aided by the action of surrounding muscles. This is why when you use eye drops, you might feel the medicine at the back of the nose or mouth. Problem is, it seems this passage is one way. That while tears can travel from the eyes into the nose, things from the nose can not travel back into the eyes. This is thought to be due to the presence of mucus, cilia and gravity.
But if onions emit volatile gasses, may be the gasses are volatile enough to beat all these obstacles and find their way into the eyes. Or perhaps breathing in aids these gases to travel past the barriers. The other possibility could be the facial nerve because it is the common entity between the eyes, nose and the tongue. This brings to mind another interesting question? How does the sense of smell influence the sense of taste?
How does the sense of smell influence taste
Smell and taste are some of the senses that make the human body functional. The reasons as to why we eat food are numerous and well known to all. some are physiological for example to grow healthy beautiful bodies, while others are cosmetic. Much as food is important for body growth, it mus have a good taste if it must go down well. The tongue and nose play a major role in how we enjoy what we eat. If these two were absent, eating would be just any other chore that must get done for survival. These two senses are vital for physical and mental preparation of the body for food. This alone is reason enough to cause suspicion that inter-dependance between the two is vital.
Lets take an example. A 500ml cup of tea with 3 tea spoon fulls of sugar, flavored with cinnamon tastes much sweeter than the same amount of tea with the same amount of sugar but without cinnamon. Even cupcakes flavored with cinnamon taste sweeter. Yet in actual sense cinnamon is not sweet at all. It is thus true that smell is really important and can surely enhance the way certain foods tastes.
The other example is when one develops the flu and the nasal passage is stuffed. Usually the sense of smell is temporarily lost for a few days. What is interesting however is that taste also gets somewhat distorted. Food isn't as tasty as usual and its not uncommon to see the victim adding an extra pinch of salt.
I have read that the nose is innervated by both the olfactory and facial nerves, while the tongue is innervated by the facial and glossopharyngeal nerves. Could the facial nerve be the link? Am appealing to the big science minds reading this article to shade some light on the subject.