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All about “Onion”

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Health profile

The onion is a universal flavor, consumed in all regions of the world. There are several varieties, some of which are particularly rich in antioxidants. The onion is part of the large family of alliacs and, like garlic, it is attributed certain beneficial properties for health.

Active ingredients and properties

Several prospective and epidemiological studies have shown that a high consumption of vegetables and fruits decreases the risk of cardiovascular diseases, certain cancers and other chronic diseases , 2 . More specifically, studies indicate that the consumption of vegetables from the alliaceae family (onion, garlic, shallot, chives, green onion, leek) could have a protective effect against stomach and intestinal cancers , 4 . To date, there is insufficient data to establish a link with other types of cancer (such as prostate, breast, esophagus and lung cancers) 4 .

Cancer. Some epidemiological studies point to the existence of a link between onion consumption and the decrease in the incidence of different types of cancer 5 . First, a synthesis of case-control studies carried out in Italy and Switzerland reveals that the consumption of one to seven servings of onions per week reduces the risks of cancer of the colon, larynx and ovaries 6 . Added to this is a lower risk of cancer of the esophagus, oral cavity and pharynx with an intake of seven or more servings of onion per week 6 . The same trends are observed for brain 7 , stomach and esophageal cancer 8(studies carried out in China). Researchers in the Netherlands report an inverse relationship between onion consumption and the incidence of stomach cancer 9 . Finally, mortality from prostate cancer would be reduced thanks to a high intake of onions 10 . The results of these observational studies should be interpreted with caution, as they do not take into account several important factors, such as the variety and method of cooking onions, as well as the precise quantities consumed. In addition, some studies have failed to significantly demonstrate such protective effects against cancer 11-13 .

The onion could act at different stages of cancer development 14 . Indeed, studies show that onion extracts can inhibit the mutation processes that trigger cancer 15 . They also decrease the proliferation of cancer cells 15-17 . These results come from in vitro and animal studies. The compounds concerned and the precise mechanisms of action are becoming better known and research is continuing.

Cardiovascular illnesses. Onions contain compounds that act on various cardiovascular risk factors 18 . The majority of studies on the subject have been carried out in vitro or in animals, apart from a few preliminary studies in humans. The onion is known for its ability to decrease platelet aggregation in vitro, an activity which is however 13 times weaker than that of garlic 19 . Note that the aggregation of platelets in the blood increases the risk of thrombosis and, by the same token, of cardiovascular disease. A recent study found that adding raw onion to pigs for six weeks did not affect platelet aggregation, but significantly decreased theirblood triglycerides 20 . It should be noted that the quantities used in these studies are equivalent to a daily consumption of half a onion and a half in humans.

A preliminary human study indicated that the consumption of approximately three medium onions (500 g), in a soup, decreased platelet aggregation ex vivo (test performed using blood drawn from subjects) 21 . Still in humans, the daily consumption of approximately 220 g of onion cooked for two weeks did not allow any positive effects to be observed on platelet aggregation 22 . Some studies have found that onions have less antiplatelet activity after cooking 19 , 23 . The antiplatelet activity is partly attributable to sulfur compounds and flavonoids(quercetin) from the onion. These two compounds could act synergistically 22 , 24 . The precise modes of action have yet to be determined 25 .

Antioxidants. Antioxidants are compounds that protect the cells of the body from damage caused by free radicals . These are very reactive molecules which are implicated in the development of cardiovascular diseases , certain cancers and other diseases linked to aging 26 . The main classes of antioxidants in onions are anthocyanins and flavonols (more specifically quercetin) 5 . Anthocyanins give the red color to certain varieties of onion, and flavonols color yellow onions 5. It should be noted that these antioxidant compounds are mainly found in the outer layers of onions 27 . The onions are low in antioxidants compared to yellow and red 16 . In addition, the varieties of red onions generally have an antioxidant content , 15 and an antioxidant activity 28 superior to the varieties of light-colored onions. A study done at Cornell University in New York State indicates that Western Yellow, New York Bold and Northern Red onions have up to eight times the antioxidant activity of other varieties . 16

Along with tea and apple, onions – especially yolks – are a major source of quercetin 29,30 . Quercetin onion would be absorbed in appreciable quantities in the body, thus resulting in an increase in the antioxidant activity in the blood 29 . This flavonoid, along with other antioxidant compounds in onions, may help decrease the incidence of certain cancers , 31 . In addition, it is now well demonstrated that flavonoids, including quercetin, have a protective action against the oxidation of LDL-cholesterol (“bad” cholesterol) 32. Thus, a high consumption of flavonols and flavones from food is associated with a lower risk of coronary heart disease 33 .

Do not Cry!
Do you cry when you cook onion? Dry those tears … The molecule responsible for the tear properties of the onion – called thiopropanethial S-oxide – is released when you defeat the bulb 31 . It is very soluble in water. This means that it can be removed when the peeled onion is rinsed under water or if it is previously cooled.

Sulfur compounds. These substances are so named because they contain one or more sulfur atoms in their chemical structure. As for garlic, sulfur compounds form when the onion is cut 34 . At this point, alliin (an inactive and odorless molecule from onions) comes into contact with an enzyme and turns into precursor compounds of the smell , flavor and tear properties of onions. A series of reactions ensue, the end products of which are a complex mixture of sulfur compounds contained in onion 31. Some of these compounds would limit the multiplication of cancer cells 5 , in addition to playing a role in the antiplatelet activity attributed to onion 5 .

Saponins. These substances have the ability to lower blood cholesterol in animals and blood clotting in vitro 35 , two effects sought to better prevent cardiovascular disease. The role of these compounds is however little known in humans.

Compounds containing selenium. Like broccoli and garlic, onions have the ability to accumulate selenium from the soil, which leads to the formation of compounds containing selenium 36 . Although it is difficult to quantify their benefits, these substances could contribute to the protective effect of onions against cancer 36 . Research is also continuing in this direction.

Other properties

Is the onion antioxidant? Moderately to strongly  : Depending on the onion varieties (yellow, white or red), the TAC index varies between 523 and 1037 umol.
Is the onion acidifying? No  : it is rather alkalizing, its PRAL index is – 1.5 mEq / 100 g.
Does the onion have a high glycemic load? Data not available.

Most important nutrients

See the meaning of the nutrient source classification symbols

 Manganese . Onions are a source of manganese for women , as manganese needs are higher in men. Manganese acts as a cofactor for several enzymes that facilitate a dozen different metabolic processes. It also participates in the prevention of damage caused by free radicals .

 Vitamin B6 . Onions are a source of vitamin B6. Vitamin B6, also called pyridoxine , is part of coenzymes that participate in the metabolism of proteins and fatty acids as well as in the manufacture of neurotransmitters (messengers in nerve impulses). It also collaborates in the production of red blood cells and allows them to transport more oxygen. Pyridoxine is also necessary for the transformation of glycogen into glucose and it contributes to the proper functioning of the immune system. Finally, this vitamin plays a role in the formation of certain components of nerve cells.

 Vitamin C . Onions are a source of vitamin C. The role that vitamin C plays in the body goes beyond its antioxidant properties; it also contributes to the health of bones, cartilage, teeth and gums. In addition, it protects against infections, promotes the absorption of iron from plants and accelerates healing.

What is a “portion” of onion worth?
Weight / volume Raw onion, 125 ml / 85 g
Calories 36
Protein 0.8g
Carbohydrates 8.6 g
Fat 0.1g
Dietary fiber 1.2g

Source  : Health Canada. Canadian Nutrient File , 2005.

Cook the onion? Sautéed or baked!
Studies have shown that boiling onions decreases their flavonoid content 37 and, therefore, their antioxidant activity 38 . When the onion is cooked in a soup or stew, this effect is of less importance, since the cooking water in which these antioxidants are found is consumed. Conversely, baking or sautéing the onion increases its flavonoid content since the water evaporates, creating a greater concentration of these antioxidants 37 .

Onion flavor and smell

The pungent flavor and strong smell of onions vary in intensity, depending on the variety. To a lesser extent, environmental factors surrounding the cultivation of onions (such as soil quality) also have an impact. Finally, the flavor and the smell of the onions become weaker the more the weight of the onion increases. Thus, the largest onions are less pungent and less fragrant than the small ones . 39


Irritable bowel syndrome
Irritable bowel syndrome is characterized by various disorders of the digestive system, including abdominal pain, flatulence, and changes in bowel movements. This disorder can also manifest as gastroesophageal reflux or dyspepsia. Some people with this syndrome may experience intolerance to various foods. Fermentable foods, such as onion, garlic and other vegetables from the alliaceae family are also implicated. Simply limiting or avoiding their consumption is often enough to alleviate the symptoms. When the symptoms are mild, or during so-called “remission” periods, it is sometimes possible to gradually reinstate these foods,

Onion over time

The term “onion” appeared in French in 1273. The final form, “onion” , will appear in the XIV th  century. The word comes from the popular Latin unio , unionis which, in Gaul, eliminated caepa (from where come “cive”, “ciboule”, “civette”, “chives”), word used until now to describe this vegetable. Why unio ? Simply because the onion is one of the few alliaceae whose bulb does not divide (we are talking about the onion in the narrow sense of the term, which excludes the shallot) and is therefore united .

Note that, according to the new botanical nomenclature, plants of the genus Allium now belong to the family of alliaceae , even if they are still sometimes classified as liliaceae or amaryllidaceae.

Although the wild ancestor of the onion has not been found, its first center of domestication could be southwest Asia. It is certainly one of the most anciently cultivated vegetables . It is mentioned in ancient Egyptian texts dating back more than 4,000 years, as well as in the Bible where it is reported that during their exodus (1,500 years before our era), the Hebrews mourned his absence, as well as that of garlic and leek. Many varieties were already grown in Greece and Rome. The Romans even dedicated particular gardens to it, the cepinae .

Onion, the baron
The expression “putting oneself in rows of onions” has little to do with the rows of onions in the garden. Rather, it alludes to the fact that the Baron d’Oignon, master of ceremonies at the court of the Valois, used to shout when he assigned their place to the lords: “Gentlemen, close your ranks”. Between them, the lords mocked the ranks of Onion.

Still, even if we already cultivated some varieties IX th  century, the onion will be really popular in Europe in the Middle Ages. It will be one of the first European plants to be cultivated in America, first in the Caribbean, where Christopher Columbus will introduce it. In the XVII th  century, it is established in the northern United States and in Canada, where it is grown as the settlers by Native Americans. The Europeans will introduce it in the east of Asia in the XIX E  century although in these regions, one prefers always to consume the numerous native species which are related to him. Today it is produced in all temperate regions of the globe and trials aimed at

Culinary uses

Culinary dishes


  • Rather sweet, Spanish or Bermuda onions, Vidalia onion and Walla-Walla are often eaten raw, in salads, burgers, etc. Onions from some red varieties are also sweet, but not all.
  • Mince a sweet onion and soak it for about fifteen minutes in ice water. Drain, dry and add salt, chopped parsley and sumac powder (sold in oriental grocery stores). Let stand 15 minutes and serve.
  • Soak onion slices with salt for one hour. Rinse, drain and serve with finely chopped dill leaves.
  • Serve onion rings with tomato slices, feta and black olives. Drizzle with oil and garnish with basil. Or serve them with the peeled slices of an orange, on lettuce, endive or escarole leaves, all washed down with a vinaigrette.


Is there onion under this frying?
If you eat fried onion rings at the restaurant, it will be difficult to comply with the food recommendations for maximum fat per day, since these rings already contain 30 g! As for the amount of onion hiding there, it rarely reaches the equivalent of a serving of vegetable.
  • Yellow onions are the most pungent of all. They are suitable for long cooking (stews, beef bourguignon) and for the preparation of funds or broths. In this case, we can leave their skin to give color to the broth. Onion studded with cloves is a classic in stews, broths and more.
  • The pearl onions are delicious cooked in butter with green peas and mint. Or glazed: cook them in a pan in butter with a pinch of sugar.
  • Making confit of onions in the mincing and making the color in a pan with melted butter. Add sugar, red wine, thyme, salt and pepper, and simmer for about 20 minutes. Serve with grilled meat, liver or chicken hearts.
  • Stuff the Spanish onions by first cutting them to three-quarters of their height and blanching them. Empty them, keeping a layer of about 1 cm. Chop the removed parts, cook them in butter, then mix them with blanched spinach, rice or semolina. Garnish the onions and braise them in the oven for about an hour. Towards the end of the cooking, add a little grated Parmesan cheese and brown. They can also be stuffed with crushed garlic, with oil and parsley, or with sauerkraut and bread crumbs.
  • In a pie , soufflé or quiche  : brown them in butter and cool them before continuing the preparation. Add bacon pieces or sausage rings, if desired.
  • The au gratin onion soup is made by sautéing finely sliced ​​onions in butter until they are brown but not burnt. Beef or chicken broth is added and baked for half an hour. Put pieces of toast on the broth and sprinkle with grated Parmesan cheese, then iron in the oven for ten minutes. If desired, add a drop of cognac or sherry before serving. Or replace half of the meat broth with cider.
  • Classic Indian cuisine, bhaji onions ( khanda bhaji ) are served as a starter or at tea time. Just finely chop the onions and let them marinate for an hour with a little sugar and salt. When they have disgorged well, mix the preparation, including liquid, with chickpea flour and chili, then form dumplings which are cooked with deep frying. Serve with a chutney.
  • To marinate them , put the onions to disgor in salted water for 12 to 24 hours. Drain, dry with a paper towel, put in jars with mustard or dill seeds. Cover with hot vinegar, close and keep for a few weeks before serving.

Organic gardening

Ideal latitude
Very sensitive to the photoperiod (distribution during the day between the duration of the diurnal phase and that of the dark phase), the onion has its preferred latitudes , according to the varieties. So, there is no point in hoping to grow Vidalia or Maui in Quebec: all that will be obtained are tiny bulbs, these varieties having been selected for lower latitudes. In their catalog, the seed producers generally indicate the ideal latitudes for a given variety.

For planting, it is always better to use young seedlings to transplant rather than onions which are more susceptible to diseases and are only available in a few varieties. In contrast to young plants, the choice is much greater, especially if you sow them yourself indoors or in the greenhouse.

Its roots being superficial, the onion needs regular irrigation throughout the season. However, all irrigation should be stopped two or three weeks before harvest, to allow the leaves and bulb to dry out, which will promote good conservation.

Avoid late application of nitrogenous fertilizers (for example compost applied on the surface), at the risk of delaying the maturation of the bulbs and causing a resumption of leaf growth. In this case, the bulb neck thickens, which is not favorable for preservation, and there is formation of double or multiple bulbs.

Mulch the rows or the border to keep the humidity and prevent the emergence of weeds, because with its narrow leaves, the onion is poorly protected. If you choose to weed with a hoe, be careful not to damage the surface roots.

By cultivating the onion and the carrot in alternating rows, we move away both the onion and the carrot fly .

Before storing the onions for the winter, let them dry for a good week in a well-ventilated place. Then keep them dry in mesh bags.

Ecology and environment

”  Mingle with your onions  ”
This expression could be the French equivalent of know your onions , a phrase born in the United States in the 1920s. It underlined that the many varieties that were cultivated at the time changed their name depending on the region where you were, which made identification difficult. “Knowing your onions” therefore meant being familiar with the varieties that were grown in his region and, by extension, knowing a subject thoroughly. “Taking care of your onions” could therefore mean “only meddling with what comes within your area of ​​competence”.

Throughout its journey through history, the onion has taken many forms, sizes, flavors and colors. It has adapted to the different climates where it was grown, to the cultivation methods and to the local culinary specialties. This ranges from the small pearl onion to the gigantic Ailsa Craig bulb, which can weigh up to 2.5 kg; the rose of Roscoff, introduced in France in 1647 by a Capuchin monk who had brought it back from Portugal, and implanted since in Brittany, with the astonishing red of Tropeo, in the shape of a soccer ball, which comes from Calabria and that the heads of large metropolitan areas literally tear themselves away. What about the sweet from the Cévennes, cultivated manually in terraces for centuries and to this other sweet from Trébons, reputed not to make people cry, and object of an annual party just for him? There is also the Walla-Walla brought back from Corsica at the end of the XIXth  century and since established in the city of Washington State which gave it its name; Georgia State Vidalia, which boasts of the sweetest onion in the world; the Creole onion, which is the only one to support storage in the hot and humid climate of Louisiana and this strange little wild onion supposed to come from Morocco that we find in some fishmongers … Not to mention the cippolini, small white, yellow or red disc, savored braised or cooked on the grill.

However, experts recognize that the massive introduction, in recent decades, of hybrid varieties, adaptable to extremely varied climates, has led to strong genetic erosion of the species Allium cepa. Result: a loss of the organoleptic qualities which make the reputation of many local varieties. In addition, hybrid varieties remain the property of large international companies which market them since they keep the secret of their parentage, which forces producers to buy new seeds from them each year. In contrast, the traditional local varieties belong to the public who consume them and to the producers who preserve their characteristics thanks to ancestral know-how. They are the ones who multiply them by using seeds they harvest from their best plants and who cultivate them taking into account the geoclimatic conditions specific to their region. It is a fact that we are just beginning to recognize: is always accompanied by a variety of flavors and culinary uses.

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