By Alyssa Morlacci
Updated on 14. Sep. 2020

They are the basis for many dishes, provide a strong aroma and come in the form of many different varieties.

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  • ...promote digestion.
    Onions ensure the intestinal flora remains healthy and digestion works well. Onions contain a relatively large amount of dietary fibers and the sulphur-containing essential oils have a positive effect.
  • ...supply important vital substances.
    Whether red, brown or white, all onions supply vitamins from the B group. The onion is also generous with vitamin C, and on top of that they have plenty of the mineral potassium to offer.
  • ...are slimming.
    Onions have few calories, hardly any fat and a lot of fiber.
  • ...add to many dishes.
    Whether braised, steamed, fried, boiled or raw, with onions almost every savory dish benefits from the ingredient's taste and health factors.
  • ...act almost like an antibiotic.
    The sulphur-containing essential oils in the onion give it a typical fragrance and pleasant pungent taste. But that's not all: These oils act like a natural antibiotic and can render bacteria in the mouth and digestive tract harmless.
  • ...can be difficult to digest raw.
    If you have a sensitive stomach, eating raw onions aren't the best decision. It helps to boil the onion briefly in water. This causes the vegetable to lose a few vitamins, but it also makes onions much easier to digest.
  • ...can cause flatulence.
    The unpleasant stomach issue does occur for some people when they eat onions. This is due to the healthy essential oils in the onion, which cause gas to form during digestion.

What You Should Know About Onions

Despite differences in appearance and taste, all inions smell spicy. This is due to their sulphurous mustard oils, which give onions their flavor and make them particularly healthy. 


Onions have been enjoyed for at least 5,000 years in Central Asia, Pakistan, India and the Mediterranean region.


Freshly harvested onions are available from July to October. Onions have a long shelf life and are therefore available from November to April.


Depending on the variety, onions taste mildly spicy to spicy-hot.


Onions: They are indispensable for everyday cooking in soups, stews, braised dishes, fried potatoes and much more. They are available all year round, but fresh onions from the first local harvest in spring taste best. They are wonderfully suited for raw consumption, for example in salads.

Red onions: Their thin, dark red to violet skin and equally reddish, mild flesh make them particularly popular as a decorative and tasty salad topping. Of course you can also cook, fry and bake with red onions, either on their own or combined with other onions to give a culinary and visual touch, for example in an onion tart, onion soup or scrambled eggs.

White onions: Italians and Spaniards love them for their sweet and mild taste. White onions are the ideal summer onion, because even those with a sensitive stomach can usually enjoy them raw. Gently and briefly steamed, white onions also add a subtle spice to finer dishes.

Pearl onions: If you only know them pickled from the glass, you are missing out! The 15 to 35 millimeter small white onions taste particularly delicious when fresh. Their mildly spicy taste makes pearl onions a delicious side dish for meat, fish or poultry. Simply peel and braise with olive oil at low heat for 10 to 20 minutes.

Yellow onions: The heavyweight of the onion family comes to us mainly from Spain. The shape and skin are reminiscent of the kitchen onion, but the yellow onion grows to a thickness of up to 20 centimeters and tastes particularly mild compared to its little sister. Its white, juicy flesh has a slight sweetness and is ideal for salads, for stewing, grilling and above all for stuffing.

Shallots: The mildest and noblest of all onions, round shallots look almost like kitchen onions but have the a different aroma. Most shallots have an elongated, pear-like shape, with the skin shimmering pink to red or coppery.

Spring onions and leeks also belong to the family. However, they are different from their relatives and therefore have their own ingredient pages for you to read.

Here you can find all onion recipes.

How Healthy Are Onions?

The onion is rightly considered a real all-around remedy for many ailments. The vegetable is full of flavonoids which, thanks to their anti-allergic and anti-inflammatory properties, can alleviate typical cold symptoms such as sore throats or earaches.

Onions have hardly any calories and don't contain any cholesterol or purines (uric acid). They're a good source of vitamin B, vitamin C and the mineral potassium. 

The sulphur-containing essential oils are good for the body and especially the intestines. They are natural substances that act similar to antibiotics: They inhibit a number of disease-causing bacteria and fungi. Small dark onions usually contain more of these substances than light ones. Thick vegetable onions are milder and therefore are less pungent. The bacteria-inhibiting effect of onion antibiotics extends to the oral cavity and the entire digestive tract.

Onions are among the foods rich in quercetin. This polyphenol stimulates the formation of mitochondria, the body's own power stations that supply our cells with vital energy.

For people with insulin resistance or diabetes, larger portions of onions are better for blood sugar levels. This is due to the sulphur-containing organic substances in the spicy tuber. They ensure the body has more insulin than usual at its disposal. Onions are also a top source of chromium. The abundant trace element ensures the body can better utilise carbohydrates. It supports the effect of insulin and can thus help regulate blood sugar.

After cutting the onion, a chemical reaction releases allicin, which studies have shown can destroy tumor cells.

Few people experience small side effects from onions. For some people, onions cause bad breath, burping or flatulence. People with a sensitive stomach often complain about onions that are difficult to digest raw. One solution can be to briefly boil them in water.

Nutritional values of onions (kitchen onion) per 100 grams  
Calories 30
Protein 1.1 grams
Fat 0.25 grams
Carbohydrates 4.9 grams
Fiber 1.4 grams

Shopping and Cooking Tips


Make sure onions feel firm and dry to the touch. If it shimmers black between the outer skins, then it is mold.


It's best to store onions in a basket so they can breathe. You should not store them in the refrigerator because they can quickly become moldy or rotten in the high humidity.


No matter if you need cubes or rings, onions can take many shapes. The easiest way to first cut the onion is in half lengthways. Do not cut away the root, it will hold the onion together when you chop it. Now you can easily peel the hard onion skins with a knife.

If you need to peel larger quantities, for example for an onion soup, there is a practical trick: Put the onions in a bowl of boiling hot water for about 1 to 2 minutes. Then lift them out with a skimmer and dip them into a bowl of ice-cold water. Then take them out and let them drain. Now the onions can be peeled easily. After peeling, chop the onions as usual. You should not leave chopped onions standing around for long, otherwise the active ingredients will decompose. Tearful eyes when cutting an onion are common and caused by the amino acid alliin in the outer cell layers and the enzyme alliinase from the cell interior, which react with each other when the vegetables are cut.

What To Make With Onions

Because there are so many varieties, there is a suitable onion for every taste and purpose. Depending on the size and variety, you can use them to make any hearty dish even more delicious. They can be finely or coarsely diced, cut into slices, and made into rings.

For the chopping to work, the knife should be sharp, otherwise it will crush the onion more than cut it. Furthermore, a blunt knife increases the risk of injury.

If you have a poor tolerance for raw onions, you can dip cubes or strips into boiling water briefly. The pieces of onion will still have some bite, but they'll be easier to digest.

Knowledge To Go

Onions add the right spice to an infinite number of dishes and also provide us with health-promoting ingredients.

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