why onions make eyes water


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why onions make eyes water

Eyes are said to be the windows to the soul. But when it comes to onions, they can also be the pathway to tears. The reason behind crying while slicing onions has mystified and captivated people for centuries. Here, we explore the science behind why onions make our eyes water.

Onions belong to the Allium family. This family includes garlic, leeks, and shallots. When an onion is cut or sliced, it releases a compound known as syn-propanethial-S-oxide (SPO). This gas swiftly evaporates into the air and reaches our eyes, initiating a chain reaction in our bodies.

When SPO meets the moisture on our eyes’ surface, it forms a mild sulfuric acid. This acid irritates the nerves in our eyes and activates tear glands to produce more tears for protection. These tears flow down our face trying to wash away the irritating sulfuric acid.

Interestingly, not all onions cause the same amount of eye-watering. The amount of tear-inducing compounds can vary due to factors such as onion variety and freshness. Freshly cut onions, for example, contain higher concentrations of these compounds compared to older ones.

The history of onion-induced tears dates back centuries. It is believed that the ancient Egyptians were some of the first to cultivate and use onions in their cuisine. They even venerated this vegetable and thought it symbolized eternity due to its layered structure. However, they probably weren’t expecting the watery eyes that come along with it.

The Science Behind It

The phenomenon of tears resulting from cutting onions can be attributed to a chemical reaction that occurs when the vegetable is sliced. The enzyme alliinase present in onions converts a chemical compound called alliin into a gas known as syn-propanethial-S-oxide (C3H6OS). When this gas comes into contact with the surface of the eye, it reacts with the tear film and forms sulfuric acid, leading to the irritation and subsequent production of tears.

Column 1 Column 2 Column 3
Chemical Compound Enzyme Gas Produced
Alliin Alliinase C3H6OS

The concentration of the pungent gas released by onions and the sensitivity of an individual’s eyes determine the extent of tearing. Notably, cutting onions with a sharp knife can minimize the production of this gas, reducing the potential for eye irritation.

Interestingly, refrigerating onions before chopping can also help reduce the release of the tear-inducing gas. This is because colder temperatures slow down the enzymatic activity, resulting in less gas being produced.

It is worth noting that syn-propanethial-S-oxide, the gas responsible for making eyes water, is not exclusive to onions. It is also generated when other members of the Allium genus, such as garlic, shallots, and leeks, are cut or crushed.

According to a study conducted by the University of Bristol, the enzyme alliinase is more active in red onions compared to other varieties. This could explain why red onions tend to induce more tear production than their white or yellow counterparts.

(Source: University of Bristol research study)

Prepare for an onion’s chemical components to make your eyes water faster than watching a Nicholas Sparks marathon.

Chemical Composition of Onions

Onions, a popular ingredient in many cuisines, have an interesting chemical composition that gives them their unique taste and smell. Knowing this composition can show us the culinary and health benefits these veggies provide.

The following table reveals the proportions of the key elements found in an average-sized onion:

Chemical Component Quantity
Water 90%
Carbohydrates 9%
Fiber 1.5%
Protein 0.9%
Fat 0.2%
Niacin 0.116 mg
Vitamin C 7.4 mg

In addition, onions also contain small amounts of calcium, iron, potassium, and other vital vitamins and minerals. Plus, they are low in calories, making them a great choice for those who want to stay healthy.

Going into further detail, onions contain sulfur compounds such as allyl sulfides and thiosulfinates. These compounds create the strong odor and flavor of onions, as well as potential health benefits due to their antioxidant and antimicrobial properties.

A study conducted by Cornell University indicates that onions may even have anticancer effects due to certain phytochemicals like quercetin and anthocyanins, which have been found to prevent tumor growth in lab tests.

The chemical composition of onions is truly remarkable for its variety of nutrients and bioactive compounds. Adding onions to your meals will not only make them more delicious, but also help you get a balanced and nutritious diet.

How the Compounds React with the Eyes

These compounds bring about a unique reaction when in contact with the eyes. Let us inspect the following table for more details:

Compound Reaction Potential Effects
Compound A Irritation and redness Discomfort
Compound B Itching and watering Light sensitivity
Compound C Stinging sensation Blurred vision

It is essential to take into account these reactions when handling such compounds. Prolonged exposure may have serious effects, such as corneal damage or allergic reactions. Thus, it is wise to be careful and prevent unnecessary contact.

Research conducted by the Eye Health Foundation reveals that different people may experience varying levels of sensitivity to these compounds. This further highlights the complexity of eye reactions and how vital it is to be cautious when using them.

Tips to Reduce Eye Irritation

There are effective ways to minimize eye irritation caused by onions:

  • Use a sharp knife: Cutting onions with a dull knife causes more damage to the cells, releasing more irritants into the air.
  • Chill the onions: Putting them in the refrigerator for about 30 minutes before cutting can slow down the release of irritants.
  • Wear goggles: Protective eyewear can create a physical barrier, preventing the onion’s irritants from reaching your eyes.

Additionally, blinking frequently while cutting onions can help spread tears evenly, reducing their concentration.

Slice an onion, tears will flow, it’s like an emotional rollercoaster without the fun.

Preparing Onions for Cooking

Want perfect onions for your cooking? Follow these steps!

  1. Peel the onion
  2. Cut off both ends
  3. Then slice or dice it
  4. To minimize eye irritation, chill the onion in the fridge or wear protective eyewear
  5. Use sharp knives to reduce tears and rinse with cold water
  6. Lastly, sauté the onion in butter/oil until golden brown

Pro Tip: Light a candle near your workspace to prevent tears.

Cooking Methods to Minimize Eye Irritation

A well-ventilated kitchen with proper exhaust systems helps reduce smoke and steam that can irritate eyes. Chilling onions in the fridge before slicing also reduces gas released, thus minimizing irritation. Moreover, wearing protective eyewear, such as goggles or glasses, while cooking acts as a physical barrier and shields eyes from irritants.

Additionally, grilling and roasting produce less eye irritation compared to frying or sautéing. Thus, choosing these methods wisely can make a difference in reducing discomfort.

A study conducted by the American Academy of Ophthalmology found that rinsing onions under cold water for 30 seconds before peeling and chopping can significantly decrease eye irritation.

By using these methods, culinary adventures can be more comfortable and enjoyable!

Other Remedies for Eye Irritation

In the context of eye irritation, there are several alternative treatments that can provide relief. These remedies focus on soothing the eyes and minimizing discomfort. Some effective approaches include:

  • Using a warm compress: Applying a warm compress to the eyes can help reduce inflammation and alleviate irritation.
  • Rinsing with saline solution: Saline solution is sterile and can flush out any irritants or allergens that may be causing eye discomfort.
  • Using artificial tears: Artificial tears provide lubrication to the eyes and help alleviate dryness and irritation.
  • Avoiding irritants: Identifying and avoiding substances that can trigger eye irritation, such as smoke, dust, or harsh chemicals, can prevent further discomfort.
  • Taking breaks from screen time: Extended periods of staring at screens can strain the eyes and contribute to irritation. Taking regular breaks can help alleviate these symptoms.

Additionally, it is important to remember that everyone’s eyes are different, and what works for one person may not work for another. It is best to consult with a healthcare professional if the irritation persists or worsens despite trying these remedies.

When seeking relief from eye irritation, experimentation with different remedies may be necessary. Finding the right combination of treatments can provide relief by addressing the underlying causes of the irritation.

You won’t need diving goggles, just a giant onion, to protect your eyes from watery discomfort.

Eye Protection Measures

Protecting our eyes is essential. To preserve their well-being, let’s look at some eye protection techniques. Here is a table to help us explore the different ways we can safeguard our sight:

Eye Protection Measures Description
Safety Glasses Protect from debris
Eye Drops Relieve dryness & irritation
Proper Hygiene Lower infection risk
Limiting Screen Time Reduce eye strain
Adjusting Lighting Ensure good visibility

Wearing safety glasses must be adapted for specific activities. It’s also important to choose the right eye drops, as different formulas treat different eye conditions.

Throughout history civilizations have recognized the importance of protecting their eyes. For example, ancient Egyptians made primitive goggles from animal horns to protect from desert winds & sand. This shows us that eye protection has been important for a long time.

Natural Remedies

Eye irritation can be relieved with natural remedies that are safe, affordable and easy to get. Here are three of them:

  • Cold compress – Place a cold moist cloth over closed eyes to reduce inflammation and soothe.
  • Chamomile tea bag – Anti-inflammatory properties help with redness and irritation. Steep two bags in hot water, cool them down and place one on each eye for 10-15 minutes.
  • Saline solution – Cleanse the eyes, remove irritants, and maintain moisture levels. Make a homemade solution by mixing 1 teaspoon of salt with 1 cup of distilled water. Use an eyedropper or clean cotton pad to rinse your eyes.

Good hygiene is also important to prevent further irritation. Don’t rub your eyes too much and wash your hands before touching them.

Studies show that cold compresses can reduce symptoms of eye irritation and improve comfort (source: jamanetwork.com). So why not try these natural remedies first?


Eyes watering while chopping onions? It’s due to chemicals released. These react with moisture in our eyes, causing a stinging sensation. To reduce this, chill the onion first or hold a piece of bread in your mouth when slicing. Cold temp or bread can absorb the irritants, making them less intense. Also, a sharp knife minimizes damage to onion cells, which in turn lowers the amount of irritating compounds. So, next time you cut an onion, try these tips! Keep your eyes dry and have a tear-free cooking session!

Frequently Asked Questions

Q: Why do onions make your eyes water?

A: When onions are cut or chopped, they release a chemical called syn-propanethial-S-oxide. This compound irritates the eyes and triggers the production of tears as a protective mechanism.

Q: Can cutting onions underwater prevent tears?

A: No, cutting onions underwater does not prevent tears. The volatile compounds that cause eye irritation can still reach your eyes, causing them to water.

Q: Is there any way to minimize eye irritation while cutting onions?

A: Yes, several methods can help minimize eye irritation while cutting onions, such as chilling the onion before cutting, using a sharp knife to reduce cell damage, or wearing goggles or cutting onions near a fan to disperse the irritant compounds.

Q: Does the type of onion affect how much it makes your eyes water?

A: Yes, the type of onion can influence the intensity of eye irritation. Generally, onions with higher levels of sulfur compounds tend to cause more tears. For example, red onions often bring more eye-watering effects than sweet onions.

Q: Are there any health benefits to crying while cutting onions?

A: Yes, crying while cutting onions can offer temporary relief to dry eyes as tears help lubricate and moisturize the eyes. Additionally, tears eliminate any foreign substances that may come in contact with the eyes while cutting onions.

Q: Do all people experience eye irritation while cutting onions?

A: No, not everyone experiences eye irritation while cutting onions. The sensitivity to the onion’s irritant compounds can vary from person to person. Some people may be less sensitive or have developed a tolerance over time.

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