Onions: Complete Guide with Benefits, Origin and Much More

The onion is one of the oldest vegetables and crops in the world. It is known all over the world and consumed in different forms. Although there are countless types of onions, in this blog we’ll talk about the bulb onion or common onion. Here you’ll learn all about this vegetable, for example:

  • What is an onion?
  • What are the characteristics of onions?
  • What types of onions are there?
  • What are the benefits of onions?
  • Where onions originated?
  • How is the onion industry in the world?
  • How onions are cultivated
  • and which products are made from onions

What is the bulb onion and what are its characteristics? 

Scientific nameAllium Cepa L.
Common nameBulb onion, head onion, egg onion, and common onion, among others.
Place of OriginAsia
HabitatTemperate regions
DistributionDiverse regions around the world.
FruitBulb onion

What is the bulb onion? 

The bulb onion is a vegetable that belongs to the Alliaceae family, specifically to the genus Allium, to which other well-known foods such as garlic also belong.

If you don’t know what onions look like before they are marketed and reach the supermarkets, below you are going to learn about their main characteristics.

Characteristics of the bulb onion plant 

Onion roots 

Its root system is shallow since, at maturity, the roots are no more than 25 cm deep and 15 cm long. The roots are thin and small in quantity, which makes it difficult to absorb water, thus this nutrient must be provided efficiently.

Onion stem 

The bulb onion has two stems. The first one is called true stem and it is the one that allows the roots, leaves, and buds to emerge, then at the top, there is the false stem which is the one that is compressed from the bases of the leaves.

Onion leaves and flowers 

The leaves grow vertically and are covered with wax that protects them from foliar diseases. When the plant is healthy it will have between 13 to 18 leaves.

The flowers are usually white or purple, these are umbel-shaped, that is, they are small flowers that are united in the same stem.

Bulb onion 

The bulb is the part of the plant that is commercialized and consumed, this germinates from the widening of the leaves that in turn create layers and thus form the onion. This can have different shapes such as round or elongated and different colors such as white, yellow, golden or copper, and red or purple.

How are bulb onion varieties classified? 

Onion varieties

Bulb onion is grown in different places all over the world. There is a great variety of these vegetables as they are characterized by their ability to adapt to any type of environmental conditions. There are different characteristics with which onions are classified, these are:


It is a term that sounds complicated, but actually, it is not. You see, onions are usually classified by the number of hours of light they receive per day, since all onions do not require the same amount, that is why there are onions of:

  • Short day: they need 12 hours of light
  • Intermediate day: they need between 12 to 14 hours of light.
  • Long day: they need more than 14 hours of light.

The color of onions

There are 3 common colors in the different varieties of bulb onions:

WhiteThe peel and flesh of this type of onion are thin and have a spicy flavor. They are used especially in Latin American and Italian cuisine.
YellowIts skin is yellow or brown and its flavor is mild. They are used in the famous French onion soup.
PurpleThe skin can have red or purple tones, is considered the strongest flavor by many people, and is used to make salads or sandwiches.


They are also classified by their shape and size.

Onion varieties

Bombay redIt has red or purple skin.
It grows well in warm, dry climates.
It germinates 150 days after transplanting.
Red CreoleIt has a shell of red and purple tones.
It remains very well in storage.
It also germinates after 150 days.
Texas GranoThe exterior is yellow or golden, the pulp is white.
It ripens 120 days after transplanting.
It doesn’t last well in storage.
Red star f1It is red or purple in color.
It germinates 110 to 120 days after being transplanted.


There are more varieties of bulb onions, but they still retain the characteristics mentioned above to be classified. It should be noted that limited information is available.

What are the benefits of the bulb onion? 

Nutritional chart of onion 

Below, you can see a nutritional table corresponding to 100 g of white bulb onion, this was extracted from the United States Department of Agriculture (USDA, 2020). With this information, it can be said that bulb onion is low in calories, low in sugars, saturated fat, and sodium.

Nutritional information of white onion 
Serving: 100 grams of white onion 
Water91,3 grams
Energy36 calories
Nitrogen0,14 grams
Protein0, 89 grams
Total Lipids (Fats)0,13 grams
Carbohydrates7,68 grams
Fiber1,2 grams
Sugars5, 76 grams
Saccharose0,59 grams
Glucose2,63 grams
Fructose2,52 grams
Lactose<0,25 grams
Maltose<0,25 grams
Galactose0,03 grams
Calcium21 milligrams
Iron0,15 milligrams
Magnesium9,3 milligrams
Phosphorus29 milligrams
Potassium141 milligrams
Sodium2 milligrams
Zinc0,12 milligrams
Copper0,047 milligrams
Selenium<2,5 milligrams

Properties of bulb onion 

Not only are onions known all over the world for their excellent taste and versatility, but also for all the benefits they have on the human body. Therefore, here you’ll learn some of the properties of this vegetable.

Onions antioxidant potential 

Bulbous onions contain high amounts of flavonoids. Let me explain, this component is found in a variety of foods, more specifically we can say that it is the natural pigment in onions giving them colors like white, yellow, or purple.

But what do flavonoids do? These nutrients act as antioxidants that protect the body from the damage that free radicals do in the body, which can cause different chronic diseases.

Is onion good for the stomach? 

Yes, bulb onions have intestinal health benefits. Well, onions contain dietary fiber that helps the body digest food properly and make it easier for food to pass through the stomach and be expelled, which is why it is a good food for people who are constipated.

In addition, they have a substance called fructans, which generally make the stomach promote the growth of healthy bacteria good for intestinal health.

Are onions good for the heart? 

Yes, onions have several benefits for cardiovascular health. According to Health And Nutrition Overview (2019), bulb onions have low amounts of sodium and saturated fats that can help lower blood cholesterol and improve blood pressure. Both of these conditions are among the major causes of cardiovascular disease. Keep in mind that to acquire these benefits, onions should be consumed together with a healthy diet.

Onions are rich in vitamins 

According to the National Onion Association (n.d.), the bulb onion is rich in different vitamins, for example:

  • This vegetable has vitamin C and can provide about 20% of the daily intake value. Vitamin C is an antioxidant; it enables the repair of human body tissue and allows the growth and development of the organism.
  • It has vitamin B6 that can provide 9% of the daily value. This nutrient strengthens the immune system, helping it to fight against bacteria that may be in the body.
  • It has potassium which can provide 4% of the daily value. Potassium is a mineral necessary for the proper functioning of the body, it helps the absorption of other nutrients, and allows the contraction of muscles, among other functions.
  • It has magnesium that can account for 10% of the daily value. Magnesium is another nutrient that ensures a healthy body, it has different functions in the body such as calcium absorption, blood sugar regulation, metabolism of fats and carbohydrates, and strengthening the immune system, among others.
  • It has calcium and can provide 2% of the daily value. As you may have heard, this nutrient is extremely important for the formation and strengthening of teeth and bones.
  • It also contains folates, providing 7% of the daily value. This component allows the body to develop tissues and protects cells.

Medicinal uses of onion 

The onion has been used for a long time as a traditional medicinal method. Some of the traditional uses that are still prevalent are:

  • They are used to treat colds, coughs, and respiratory ailments, among other such symptoms. In Cuba, people mix onion juice, lemon juice, and honey to treat the aforementioned.
  • It is consumed raw to treat constipation.
  • People from South America generally associate onion with good health because it strengthens the immune system and fights infections.
  • In Africa, the bulb onion is used as an antibiotic. It is used to treat diabetes, mixed with salt and wine to treat dog bites, among other uses.
  • In India, it is used to treat diarrhea and intestinal problems, among other uses.

Where did the onion originate? 

Onions with their stems and leaves

There are two main theories defining the origin of onions but both claim that this vegetable originated in Asia approximately 5,500 years ago. The first theory says that the onion originated in Central Asia and the second says that it originated in the Middle East, more specifically Iran and Pakistan.

Onions were recorded in ancient Indian writings and it is also said that they were grown in China approximately 5,000 years ago. In addition, there have been found engravings in the tombs of the pharaohs of Ancient Egypt dating from 3200 to 2780 B.C., which demonstrated that the onion was quite important in the diet of the Egyptians, as well as garlic and radish.

Interestingly, this vegetable was economical so it was the most consumed food by the slaves when the pyramids were built. Onions were also used in Egypt to make offerings at funerals between 2780 and 2100 BC.

In Ancient Egypt, people thought that the spherical shape of the bulb onion and its rings symbolized eternity. Onions have also been found in different body parts of mummies, for example, in the pelvic area, thorax, chest, and ears, among others. In fact, in King Ramses IV’s tomb, onions were found in his eye sockets.

This can be explained from different points of view. On the one hand, it was believed that the onion had powers and that its aroma would make the dead breath again. and on the other hand, it is said they did so because the antiseptic (germ-fighting) powers of the onion would help the dead in the afterlife.

With the increasing popularity of the onion, it was more common to find records of this vegetable in different writings, for example, there are records of the onion in the Bible. Additionally, it was of great importance in Greece, and one of its most peculiar uses was to strengthen the Olympic players. They were given onion juice before the competitions, and they ate a lot of onions and rubbed their bodies with the vegetable as they believed it would give them strength.

The Romans were the ones who introduced onions in Europe during their trips to their provinces in England and Germany. After the fall of the Roman Empire, Europe entered a period of crisis in which food shortages prevailed and the onion became an important source of food, but not only that, it was also used as a method of traditional medicine. Around the 15th century, Europeans began to introduce onions to the New World, i.e. America.

It is also said that Russian soldiers carried onions in World War II because of their healing properties that allowed them to cure infections. Onions have been since ancient times a prized food for consumption and to treat different conditions, creating different traditional methods that may be somewhat rare, anyway, the history of the onion is impressive, isn’t it?

Industry of onion in the world 

Top 5 onion-producing countries 

Below, you can see a chart showing the 5 countries that produced the most onion in the world in 2020, according to the Food and Agriculture Organization of the United Nations (FAO).

PositionCountryExported amount in tons
1 °India26’738.000
2 °China23’659.708
3 °United States of America3’821.044
4 °Egypt3’155.649
5 °Turkey2’280.000

1. India 

In 2020, it was the largest producer with a yield of 26,738,000 tons, but this is not always the case as it is continually fighting for this position with China. Indian onions are known for their exquisite taste, the cultivation of this vegetable is done in two periods: the first runs from November to January and the second runs from January to May.

India has more than 1 million hectares dedicated to onion cultivation, and the states that produce the most onions are Madhya Pradesh, Maharashtra, and Karnataka.

2. China 

Different types of onion are grown in China, but Allium Cepa is one of the most famous. In fact, the crops of the genus Allium are quite important in the Chinese industry, occupying 10% of the vegetable crop area of the country.

In the year 2020, they produced 23,659,708 million tons. It is worth noting that China is a pioneer in technology, and for this reason, they continually seek to create ways to increase the amount of production in their crops.

3. United States of America 

The United States of America had a production of 3,821,044 tons in 2020 and has approximately 125,000 hectares dedicated to the cultivation of white, yellow and purple bulb onions. Major states producing this vegetable include California, Washington, Idaho, and Oregon.

Onion crops are grown year-round but differ in flavor, summer and spring crops are sweet or mild, and fall and winter crops are mild to pungent.

4. Egypt 

The Egyptian country knows onion very well as it is part of its history as a nation. In 2020 it produced 3,155,649 tons of onion and has a cultivation area of more than 87 thousand hectares that contributes around 3.08% to world production.

5. Turkey 

Turkey, on the other hand, produced 2’280,000 tons and has more than 68 thousand hectares for onion cultivation, contributing approximately 2.20% of world production.

Top 5 onion exporting countries 

Here you can find out the export dynamics of the onion industry, according to FAO (2020).

PositionCountryExported amount in tons
1 °The Netherlands1.751.363
2 °India1.448.718
3 °China881.314
4 °Mexico424.408
5 °Egypt369.240

1. The Netherlands 

The Netherlands has a limited crop area but is a major figure in the food industry. The climate is one of the factors that helps them to provide quality onions. In fact, onions are ranked 6th out of the top 10 most important agricultural commodities in this country.

Onions from the Netherlands account for 15% of the world’s exports and are exported to more than 130 countries.

2. India 

India, besides being the main producer of onion in 2020, is also one of the most important exporters of this vegetable; this year they exported 326,640 dollars. In addition, onions rank 6th among the 10 most important raw materials for the country. The main countries to which it exports onions are:

3. China 

China, as you know, is one of the main producers of onions worldwide. In 2020 they exported $495,414 in value, ranking 2nd in the top 10 countries that exported the most by monetary value. Some of the countries to which it exports onion are:

4. Mexico 

Mexico is the only country on the American continent that is positioned in this top 5; onion exports are really important. In 2020 they exported a value of 419,754 dollars, which made it rank 3rd among the countries that exported the most in monetary value. Some of the countries it exports to are:

5. Egypt 

Egypt is not only one of the top 5 onion producers in the world, but also one of the largest exporters. In the year 2020, they exported a value of $175,100. This amount made it occupy the 6th place of the top 10 countries that exported the most in monetary value.

In addition, onions ranked 4th of the 10 most important raw materials for the country. Some of the countries to which it exports are:

Top 10 countries with the highest onion imports 

In the following table, you’ll see the 10 countries that imported the most onion in 2019 and 2020 so you can make a comparison. Information taken from FAO.

PositionCountries 2019Imports in tons 2019Countries 2020Imports in tons 2020
1 °United States543.407Bangladesh663.895
2 °Malaysia504.692United States561.344
3 °United Arab Emirates368.145Malaysia479.729
4 °United Kingdom  of Great Britain and Northern Ireland358.796United Arab Emirates390.053
5 °The Netherlands344.863Saudi Arabia329.604
6 °Saudi Arabia295.833United Kingdom  of Great Britain and Northern Ireland 302.326
7 °Germany283.332Sri Lanka272.079
8 °Japan280.126Germany248.903
9 °Sri Lanka259.760Irak246.000
10 °Bangladesh255.133The Netherlands233.044

How to grow bulb onions? 

Onions in the ground


The bulb onion fits in different types of climates, the minimum temperature needed for it to germinate is 5 °C and the maximum temperature is 36 °C; although temperatures around 20 to 26 °C are recommended.

The temperature is an extremely important factor that determines the quality of the bulb, which is the marketable part of the plant. Optimally, bulb onions should be grown at temperatures between 15.5 to 21.1 °C to achieve high bulb quality.


Onions require light to medium textured soils preferably of a sandy loam type, with a good amount of organic matter and good drainage. These characteristics will allow the roots and bulbs to develop.

Precipitation and altitude 

Bulb onion crops should have a rainfall of 400 to 1500 mm. Onions require constant water irrigation, which can be done every 2 to 3 days.

Finally, onions grow best from altitudes of 2800 to 3200 meters above sea level.

Propagation of onion 

There are two methods for the propagation of onion:

  1. Seeding by transplant: this is the most widely used method because it yields the highest quality onions. To do this, the seeds should be sown in a seedbed, where they should be left for about 2 and a half months. Then they are transplanted to the cultivation area and approximately 3 months after being transplanted, the vegetable will be ready.
  2. Seed by cutting: this method consists of using the bulb onions that don’t meet the qualifying conditions to be marketed, which are usually the smallest ones. When chosen, they are left to dry for 15 to 20 days and then planted directly in the growing area.

Onion harvesting 

The harvest is done when the bulb onions are ripe, which can be determined in 2 ways: the first is when the neck of the plant is bent to one side, and the second is when the onion leaves turn yellow.

The ideal time to harvest is when 50 to 60% of the onion leaves are drooping or folded. To speed up this process, the remaining percentage undergoes a process of leaf drying. Thus, after 10 to 15 days the bulb onions are harvested manually or mechanically.

Post-harvest of onions 

After the onions have been harvested they go through a process of drying to eliminate the moisture present and avoid the appearance of diseases such as fungi.

After the onions are ready, they are sorted by size and packed in net bags of 18 to 20 kilograms. They are generally marketed immediately after being packed.

What products are made from bulb onions? 

Onion rings

How are onions traditionally consumed? 

Generally, these onions are used fresh to prepare different homemade dishes or are included in them. For example:

  • Salads
  • Soups
  • Sandwiches
  • Hamburgers
  • Caramelized onions
  • Roasted onion
  • Baked onion rings
  • Onion pie, etc.

Onion industrial products 

The bulb onion is an extremely versatile vegetable that has gained importance in companies manufacturing products for sale in supermarkets, some of them are:

  • Onion paste
  • Frozen onion
  • Fried onion in oil
  • Crunchy fried onion
  • Onion powder
  • Onion confit
  • Onion oil concentrate
  • Dehydrated onion
  • Onion-flavored potato chips in packages
  • Onion pastes, etc.

Onion cosmetic products 

The bulb onion, in spite of its particular smell, is widely used in the beauty industry because of the benefits it has. Some of the properties that the bulb onion has on the skin are its capacity to reduce inflammation and scarring, soothe wounds, eliminate or reduce skin imperfections and even help hair growth.

That’s why now the different companies producing cosmetics and hygiene products include this vegetable in products such as:

  • Shampoos
  • Conditioners
  • Hair masks
  • Onion hair oil
  • Hair treatments, etc.


As you can see, the bulb onion is a vegetable with a history of thousands of years. Since ancient times and until today, it has been considered valuable not only for consumption but also for its traditional medicinal use or for the production of cosmetic or industrial products. We encourage you to include the bulb onion in your daily diet and take advantage of all it has to offer.