Onion

The onion (Allium cepa L., from Latin cepa "onion"), also known as the bulb onion or common onion, is a vegetable and is the most widely cultivated species of the genus Allium.

This genus also contains several other species variously referred to as onions and cultivated for food, such as the Japanese bunching onion (Allium fistulosum), the tree onion (A. ×proliferum), and the Canada onion (Allium canadense). The name "wild onion" is applied to a number of Allium species, but A. cepa is exclusively known from cultivation. Its ancestral wild original form is not known, although escapes from cultivation have become established in some regions.[2] The onion is most frequently a biennial or a perennial plant, but is usually treated as an annual and harvested in its first growing season.

The onion plant has a fan of hollow, bluish-green leaves and its bulb at the base of the plant begins to swell when a certain day-length is reached. In the autumn (or in spring, in the case of overwintering onions), the foliage dies down and the outer layers of the bulb become dry and brittle. The crop

is harvested and dried and the onions are ready for use or storage. The crop is prone to attack by a number of pests and diseases, particularly the onion fly, the onion eelworm, and various fungi cause rotting. Some varieties of A. cepa, such as shallots and potato onions, produce multiple bulbs.

Onions are cultivated and used around the world. As a food item, they are usually served cooked, as a vegetable or part of a prepared savoury dish, but can also be eaten raw or used to make pickles or chutneys. They are pungent when chopped and contain certain chemical substances which irritate the eyes.

Onion types and products

Sliced red onions

Jar of pickled onions

Common onions are normally available in three colour varieties. Yellow or brown onions (called red in some European countries), are full-flavoured and are the onions of choice for everyday use. Yellow onions turn a rich, dark brown when caramelized and give French onion soup its sweet flavour. The red onion (called purple in some European countries) is a good choice for fresh use when its colour livens up the dish; it is also used in grilling. White onions are the traditional onions used in classic Mexican cuisine; they have a golden colour when cooked and a particularly sweet flavour when sautéed.

While the large, mature onion bulb is most often eaten, onions can be eaten at immature stages. Young plants may be harvested before bulbing occurs and used whole as spring onions or scallions. When an onion is harvested after bulbing has begun, but the onion is not yet mature, the plants are sometimes referred to as "summer" onions.

Additionally, onions may be bred and grown to mature at smaller sizes. Depending on

the mature size and the purpose for which the onion is used, these may be referred to as pearl, boiler, or pickler onions, but differ from true pearl onions which are a different species. Pearl and boiler onions may be cooked as a vegetable rather than as an ingredient and pickler onions are often preserved in vinegar as a long-lasting relish.

Onions are available in fresh, frozen, canned, caramelized, pickled, and chopped forms. The dehydrated product is available as kibbled, sliced, ring, minced, chopped, granulated, and powder forms.

Onion powder is a seasoning widely used when the fresh ingredient is not available. It is made from finely ground, dehydrated onions, mainly the pungent varieties of bulb onions, and has a strong odour. Being dehydrated, it has a long shelf life and is available in several varieties: yellow, red, and white.

Historical use

A red onion

Bulbs from the onion family are thought to have been used as a food source for

millennia. In Bronze Age settlements, traces of onion remains were found alongside date stones and fig remains that date back to 5000 BC. However, whether these were cultivated onions is not clear. Archaeological and literary evidence such as the Book of Numbers 11:5 suggests that onions were probably being cultivated around 2000 years later in ancient Egypt, at the same time that leeks and garlic were cultivated. Workers who built the Egyptian pyramids may have been fed radishes and onions.

The onion is easily propagated, transported, and stored. The ancient Egyptians revered the onion bulb, viewing its spherical shape and concentric rings as symbols of eternal life. Onions were even used in Egyptian burials, as evidenced by onion traces being found in the eye sockets of Ramesses IV.

In ancient Greece, athletes ate large quantities of onion because it was believed to lighten the balance of the blood. Roman gladiators were rubbed down with onions to firm up their muscles. In the Middle Ages, onions were such an important food that people paid their rent with onions, and even gave them as gifts. Doctors were known to prescribe onions to facilitate bowel movements and erections, and to relieve headaches, coughs, snakebite, and hair loss.

Onions were taken by the first European settlers to North America, where the Native Americans were already using wild onions in a number of ways, eating them raw or cooked in a variety of foods. They also used them to make into syrups, to form poultices, and in the preparation of dyes. According to diaries kept by the colonists, bulb onions were one of the first things planted by the Pilgrim fathers when they cleared the land for cropping.

Onions were also prescribed by doctors in the early 16th century to help with infertility in women. They were similarly used to raise fertility levels in dogs, cats, and cattle, but this was an error, as recent research has shown that onions are toxic to dogs, cats, guinea pigs, and many other animals.

Nutritional highlights

More than just a tasty culinary plant, the onion contains natural sugar, vitamins A, B6, C and E, minerals such as sodium, potassium, iron and dietry fibre. In addition, onions are a good source of folic acid.

Raw onions

Nutritional value per 100 g (3.5 oz)

Energy                                   166 kJ (40 kcal)

Carbohydrates                                9.34 g

Sugars                                               4.24 g

Dietary fiber                                                1.7 g

Fat                                                      0.1 g

Protein                                              1.1 g

Vitamins

Thiamine (B1)                                  (4%) 0.046 mg

Riboflavin (B2)                                (2%) 0.027 mg

Niacin (B3)                                       (1%) 0.116 mg

Pantothenic acid (B5)                   (2%) 0.123 mg

Vitamin B6                                       (9%) 0.12 mg

Folate (B9)                                       (5%) 19 μg

Vitamin C                                          (9%) 7.4 mg

Minerals

Calcium                                             (2%) 23 mg

Iron                                                    (2%) 0.21 mg

Magnesium                                      (3%) 10 mg

Manganese                                      (6%) 0.129 mg

Phosphorus                                     (4%) 29 mg

Potassium                                         (3%) 146 mg

Zinc                                                    (2%) 0.17 mg

Other constituents

Water                                                            89.11 g

Fluoride                                            1.1 µg

Here's a quick glimpse at their incredible health benefits:

The phytochemicals in onions along with their vitamin C help improve immunity.

Onions contain chromium, which assists in regulating blood sugar.

For centuries, onions have been used to reduce inflammation and heal infections.

Do you enjoy sliced onions with your food? If yes, rejoice! Raw onion lowers the production of bad cholesterol (LDL), thus keeping your heart healthy.

A powerful compound called quercetin in onions is known to play a significant role in preventing cancer.

Got stung by a honeybee? Apply onion juice on the area for immediate relief from the pain and burning sensation.

Onions scavenge free radicals, thereby reducing your risk of developing gastric ulcers.

Those bright green tops of green onions are rich in Vitamin A, so do use them often.

Which type of onions are the healthiest? Researchers from Cornell studied 11 onion varieties, and found that shallots and Western yellow onions were the healthiest for their phenolic and flavonoid content.

Are raw onions good for you?

Furthermore, onions contain fiber and folic acid, a B vitamin that helps the body make healthy new cells. Onions are healthy whether they're raw or cooked, though raw onions have higher levels of organic sulfur compounds that provide many benefits, according to the BBC.

Are onions nutritious?

Onion Nutrition Facts. In the rush to gather health information on the processed foods we eat, it can be easy to forget to check the nutritional facts of vegetables like the onion. Onions are high in vitamin C, a good source of fiber, and with only 45 calories per serving, add abundant flavor to a wide variety of food.

What are the health benefits of onions?

Here's a quick glimpse at their incredible health benefits:

The phytochemicals in onions along with their vitamin C help improve immunity.

Onions contain chromium, which assists in regulating blood sugar.

For centuries, onions have been used to reduce inflammation and heal infections.

Are onions a vegetable?

The onion (Allium cepa L., from Latin cepa "onion"), also known as the bulb onion or common onion, is a vegetable and is the most widely cultivated species of the genus Allium.

Health benefits

Heart health

According to Jarzabkowski, onions encourage a healthy heart in many ways, including "lowering blood pressure and lowering heart attack risk." A 2002 study in the journal Thrombosis Research suggested that sulfur acts as a natural blood thinner and prevents blood platelets from aggregating. When platelets cluster, the risk for heart attack or

stroke increases. This research further supports a similar 1992 study in Thrombosis Research that focused on sulfurs in garlic. Furthermore, a 1987 animal study in the Journal of Hypertension demonstrated delayed or reduced onset of hypertension with sulfur intake. However, the authors said more research was needed to determine if this benefit might be found in humans.

The quercetin in onions may also help prevent plaque buildup in the arteries, which reduces the risk of heart attack and stroke, according to the University of Maryland Medical Center. But since most of the studies in this regard have focused on animals, more research is needed to understand the effects in humans.

Anti-inflammatory

Onions’ sulfurs may be effective anti-inflammatory agents, according to a 1990 study in the journal International Archives of Allergy and Applied Immunology. Quercetin has been found to relax the airway muscles and may provide relief of asthma symptoms, according to a 2013 study in the American Journal of Physiology.

Immune system

"The polyphenols in onions act as antioxidants, protecting the body against free radicals," said Anne Mauney, a dietitian based in Washington, D.C. Eliminating free radicals can help encourage a strong immune system. According to the University of Maryland Medical Center, the quercetin in onions also reduces allergic reactions by stopping your body from producing histamines, which are what make you sneeze, cry and itch if you're having an allergic reaction.

Cancer

Quercetin may be a powerful anti-cancer agent, according to Jarzabkowski. The University of Maryland Medical Center said that quercetin may especially inhibit cancer cells in "breast, colon, prostate, ovarian, endometrial, and lung tumors."

The National Onion Association discussed a recent study from the Netherlands that showed that people who ate onions absorbed twice as much quercetin as those who drank tea, and more than three times as much quercetin as those who ate apples, which are other high-quercetin sources. Red onions are especially high in quercetin, according to the association. Shallots and yellow onions are also good options. White onions contain the least amount of quercetin and other antioxidants.

Digestion

The fiber in onions promotes good digestion and helps keep you regular. Additionally, onions contain a special type of soluble fiber called oligofructose, which promotes good bacteria growth in your intestines. One 2005 study in Clinical Gastroenterology and Hepatology found that oligofructose may help prevent and treat types of diarrhea. The phytochemicals in onions that scavenge free radicals may also reduce your risk of developing gastric ulcers, according to the National Onion Association.

Regulating blood sugar

The chromium in onions assists in regulating blood sugar. The sulfur in onions helps lower blood sugar by triggering increased insulin production. One 2010 study in the journal Environmental Health Insights revealed that this might be especially helpful to people with people with diabetes. People with Type 1 and Type 2 diabetes who ate red

onions showed lower glucose levels for up to four hours. 

Bone density in older women

A 2009 study in the journal Menopause found that daily consumption of onions improves bone density in women who are going through or have finished menopause. Women who ate onions frequently had a 20 percent lower risk of hip fracture than those who never ate onions.

Health risks

While not especially serious, eating onions can cause problems for some people. The carbohydrates in onions may cause gas and bloating, according to National Digestive Diseases Information Clearinghouse. Onions, especially if consumed raw, can worsen heartburn in people who suffer from chronic heartburn or gastric reflux disease, according to one 1990 study in the American Journal of Gastroenterology.

Eating a large amount of green onions or rapidly increasing your consumption of green onions may interfere with blood thinning drugs, according to the University of Georgia. Green onions contain a high amount of vitamin K, which can decrease blood thinner functioning.

It is also possible to have a food intolerance or an allergy to onions, but cases are rare, according to an article in the Journal of Allergy and Clinical Immunology. People with onion allergies may experience red, itchy eyes and rashes if an onion comes into contact with the skin. People with an intolerance to onions may experience nausea, vomiting and other gastric discomfort.

Lastly, Jarzabkowski encouraged people to make sure their onions are fresh. "Onions keep for a long time," she said, "but they still spoil."

Chicken salad with onion pickle

A Vietnamese dish full of vibrant, punchy flavours that are lifted and brightened by the onion pickle.

Serves 2–3

3 chicken thighs, skin on and bone in

1 chicken stock cube

200g basmati rice

1 knob of butter

1 garlic clove, finely chopped

10 hot mint sprigs (or Thai sweet basil), chopped

A small handful of coriander, stalk on, chopped

A pinch of black pepper

For the onion pickle

1 red onion, thinly sliced

3 tbsp cider vinegar

1 tbsp sugar

A pinch of sea salt

A pinch of black pepper

For the dipping sauce

2 tbsp fish sauce

2 tsp sugar

2cm piece of fresh ginger, finely chopped

1 bird’s eye chilli, finely chopped

1 garlic clove, finely chopped

1 tbsp cider vinegar

Chicken milanese + an escarole salad

Grey Chutney Chicken Salad

Easy French Onion Chicken Salad