Properties and Benefits of Onions

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Though it is nothing more than an ordinary vegetable, the onion is the secret savory ingredient in most traditional dishes around the globe, giving home-cooked meals an incredibly delicious and rich taste. Nutritionally speaking, onions contain small amounts of almost all essential nutrients, from folate, vitamins B1, B6 and C to manganese, phosphorus, iron, copper and potassium. Red onions further contain strong antioxidants called anthocyanins which protect against oxidative stress and contribute to overall better health.

Though it may sometimes cause minor to severe heartburn to those of you with slightly more sensitive stomachs or with existing digestive conditions, especially when eaten raw, the onion is quite the miracle vegetable. It is rich in antioxidants called flavonoids. Believe it or not, the outer, brown skin of the onion has the highest concentration of quercetin, a bioflavonoid with strong anti-inflammatory and antioxidant properties.

Onion benefits

What antioxidants do is protect cells from damage caused by harmful free radicals and can even reverse existing cell damage. This is good because extensive cell damage causes inflammation in the body and can encourage the onset of chronic diseases over time. Nevertheless, most of us avoid eating onions, and garlic too, because of their pungent odor caused by natural sulfur compounds. It is these compounds that make certain people who eat onions and garlic smell bad. But the members of the Allium family have powerful antibiotic properties, highly beneficial for our health.

The fact that onions and garlic are mild natural antibiotics is well known and the main reason why people have been eating the two vegetables consistently throughout the cold season, in hopes of repelling colds, flu viruses and other respiratory infections. In the past, people would make tea from boiled or baked onion bulbs and drink it to calm cough, sore throat irritation and speed up recovery. I remember my grandmother used to make me tea from baked onion skins because even back then people knew that this average vegetable could cure bacterial infections, without the scientific evidence to support it.

Onions help lower LDL (bad) cholesterol and triglyceride levels and even improve the membrane function of red blood cells. All of this makes them our heart and cardiovascular system’s best ally. However, researchers advise us that it is best to eat onions in combination with other vegetables which boost their properties by adding more nutrients and antioxidants to our diet.

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Some studies suggest that the onion is efficient at increasing bone density, which is great news especially for women going through menopause. There is strong evidence suggesting that it can reduce the risk of hip fractures in women after the age of menopause, if eaten on a regular basis (daily). At the same time, both raw and cooked onions can have an irritating effect on the stomach and trigger or worsen an existing gastrointestinal condition.

The most common side effects of eating onions include heartburn, acid reflux, gastritis and general stomach upset with possible bloating, abdominal pain and other symptoms. Some people may experience an allergic reaction to onions. Overall, the vegetable is best eaten in moderation and those allergic to it, heartburn, acid reflux and gastritis sufferers should simply avoid eating onions. See what are the 11 side effects of eating onions.

The onion is a source of inulin, a type of soluble dietary with benefits on the digestive system. Inulin helps regulate digestion, has prebiotic effects feeding the good gut bacteria and relieves constipation. On average, there is about 1.7 g of dietary fiber per 100 g of onion, and the vegetable contains both soluble fiber like inulin and insoluble fiber. A recommended intake of 28 g of fiber a day for the average adult can contribute to cardiovascular benefits such as lower total cholesterol levels, constipation relief and weight loss.

Moreover, the onion is a potent natural anti-inflammatory, although, it would appear, not as strong as its relative garlic. Reducing inflammation in the body has been associated with lower risks of chronic disease and overall better physical and mental health. The vegetable is also famous for its cancer-preventing properties: if eaten regularly, onions supply important amounts of antioxidants that offer a certain level of protection against oxidative stress and cell damage, potentially reducing cancer risks.

Though the majority of us prefer it in its bulb form, new onions are just as healthy. Spring onions, green onions, new onions or scallions can be eaten raw, finely sliced on a piece of bread rubbed with a few drops of olive oil. They are slightly more tender and a bit less sharp-tasting than bulb onions, with maybe a hint of a sweet aftertaste. Onions are best kept in cool, dry places and the best way to store them is to tie their leaves together in a sort of a crown which can be then hanged in a cool, dry place.

Nutritional Facts onions

What do bulb onions look like?

There is not better way to describe onions than saying they look like ovoid bulbs made of tightly wrapped, crisp, meaty leaves covered by a paper-thin skin. The bulb onion grows underground, but continues above ground with long, green, upright, hollow stems that thin towards the tip. Colors may vary from white to yellow-brown and red-purple. Also see the benefits of red onion.

What do bulb onions taste like?

Onions come in a variety of colors and shades of color: there are white onions, scallions or green onions, yellow and red onions, one more or less pungent and sweet than the other, to please everyone’s taste. The typical bulb onion has a crisp, meaty texture. Some varieties have a sharp, acidic, spicy taste while others are mildly pungent with a sweet aftertaste. Cooked onions will taste sweet.

More nutrition facts and benefits

It is recommended to avoid cutting onions long before using them because they tend to oxidize and lose their properties. And it’s a shame because they have powerful antibacterial properties. If you take a look at the nutritional table above, you will see just how many vitamins onions contain, albeit in small amounts.

You will notice that vitamin C is on top of the list with 7.4 mg of ascorbic acid per 100 g. But remember that vitamin C is sensitive to heat so cooking the bulbs will cause them to lose all of their vitamin C content. Other vitamins and minerals in onions include vitamin B6, folate, vitamin B1, manganese, phosphorus, potassium, magnesium, copper and iron. The vegetable has many other phytochemicals, natural compounds with beneficial effects on our health.

The best way to enjoy the wonderful properties and health benefits of onions is to consume them fresh as often as possible. Raw onions have a high content of naturally-occurring organic sulfur compounds which, according to researchers, boast anti-proliferative, anti-inflammatory as well as immune-boosting properties. The disadvantage is the same compounds that give the bulbs their flavor and some of their benefits can make you smell bad (read more about garlic body smell).

This strong-smelling odoriferous vegetable also contains generous amounts of highly bioavailable quercetin, a potent antioxidant polyphenol with impressive anticancer properties. Unlike vitamins, for example, quercetin is not affected by cooking heat, meaning that cooked onions have just as much of this potent antioxidant as raw ones.


Overall, onions are healthy vegetables, especially when eaten raw. It has been shown that regular consumption of moderate amounts is beneficial for your health as it can protect against a variety of health conditions. However, because this mighty vegetable can cause bloating and stomach discomfort, allergies and worsen gastritis and acid reflux problems, you might want to stay away from it if it is causing you digestive upset or any other side effects.