Why Do We Have to Cry When We Cut Onions

When people cut an onion, it irritates their eyes and some of them cry. Have you ever wondered why? Here we explain it to you.

Why Do You Cry Cutting Onions

When we cut onion, two substances mix producing sulfurous gas, which decomposes into sulfuric acid when it comes into contact with water, as in wet eyes. The brain responds by instructing the tear ducts to produce more water, i.e. tears, to dilute the acid and thus protect the eyes.

Despite the unpleasant side effects of cutting, onions should not be banned from the menu. In addition to vitamins and minerals, they contain other health-promoting substances such as flavonoids and organic sulfides. Among other things, these can suppress the growth of viruses, bacteria and fungi and reduce the risk of cardiovascular diseases and certain cancers.

How to cut onions without irritating the eyes:

• Use kitchen goggles to protect your eyes.
• Cut the onion under cold water. The volatile sulfur compounds are released, but they react with the water and do not get into your eyes.
• Freeze the onion for about 10 minutes before cutting. The cold temperature of the onion slows down the reaction that produces these volatile sulfur compounds.
• A sharp knife is very important as it makes the cut more precise and tears fewer layers of onion.
• If you know how to cut quickly, this is the ideal method because the emissions are shorter and less harmful to the eyes.

The human eye is a wonderful organ. It allows us to see the world from a distance and up close in superb quality, in spectacular colors and in three dimensions. Thanks to the great capabilities of the eye, vision became the dominant among the senses with which we perceive the world.

In accordance with its position as the leading sensory organ in the human body, the eye enjoys a multi-level protection for the sole purpose of protecting it from any damage:

1. In the first place in this protective system ranks the eye socket, which shields it from severe mechanical damage.
2. Right after that comes the eyelid, which closes in response to any threat of injury or entry of a foreign object into the eye.
3. The third and final component in the eye’s protective system is probably the most amazing and interesting: the tears.

Chemical Complexity of Tears

A closer look reveals that tears are much more than merely a protective layer. In terms of composition and function, not all tears are the same. Tears often serve as an instrument for transmitting overt or covert social and chemical messages between people.

Each eye has a lacrimal gland (glandula lacrimalis) that continuously produces new tears. The old tears are drained through two openings called lacrimal puncta (puncta lacrimalia).

In fact:

• The eye is constantly shedding some tears
• Tears do not flow in a continuous stream
• We produce about 120 liters of tear fluid annually

We usually do not feel the tears that are produced continuously, the so-called basal tears. Three layers compose them:

1. The first is a mucilaginous layer. Above that is a watery layer that keeps the eye moist
2. The watery layer is rich in enzymes and antibacterial substances that repel and kill bacteria
3. The last is a lipid layer, or fat layer. The lipid layer keeps the surface of the eye smooth so that we can see sharply, and acts as a kind of cover that prevents the two lower layers from evaporating

Reflex Tears and Emotional Tears

The tears we are most aware of are reflex tears and emotional tears. Reflex tears are a flushing mechanism of the eye. Reflex tears are secreted in response to the threat of intrusion of a foreign body.

When dangerous chemicals, harmful microorganisms, or solid particles might enter the eye, the glands secrete large amounts of reflex tears. For example: as a reaction to gas emitted from onions. We may suddenly find ourselves with watery eyes and wet cheeks.