Health Benefits of Onions

The health benefits of onions are often overlooked because of their pungent smell and sharp taste and many people prefer to give them a miss. What a shame if that's the case for you! If you want to know what you're missing read on and you might change your mind.

People have known of the health benefits of onions for thousands of years, but only relatively recently scientists have started to do a lot of research into the health giving properties of this humble vegetable, and guess what?

Studies after studies have confirmed that onions indeed possess many active compounds that have been proven beneficial for all sorts of conditions.

As you read the article, look out for the answer to these questions:

  • Can you name some of the nutrients contained in onions?
  • What causes the characteristic pungent aroma associated with onions that causes your eyes to water?
  • Why do onions mix well with protein?
  • What is quercetin, and what health benefits does it have?
  • Why are onions good at detoxifying the body of heavy metals?
  • What can onions do for the heart?
  • In what way do onions protect from cancer?
  • How do onions help lower blood sugar?

Onions Nutritional Highlights

chopped onions have more health benefits

When you think of foods containing vitamin C, onions may not come to your mind, but, as it happens, onions are a very good source of vitamin C, as well as B6, biotin, chromium, calcium and dietary fibre. In addition, they contain good amounts of folic acid and vitamin B1 and K.

A 100 gram serving provides 44 calories, mostly as complex carbohydrate, with 1.4 grams of fibre.

Like garlic, onions also have the enzyme alliinase, which is released when an onion is cut or crushed and comes into contact with another enzyme also present in onions, alliin, which has no smell. When the two enzymes combine, they form another compound called allicin, well-known for its health benefit, but the characteristic aroma is also released and causes your eyes to water. So as tears stream down your face as you cut onions, think of the all the wonderful health benefits that you're going to enjoy.

They also contain flavonoids, which are pigments that give vegetables their colour. These compounds act as antioxidants, have a direct antitumour effect and have immune-enhancing properties.

Onions contain a large amount of sulphur and are especially good for the liver. As a sulphur food, they mix best with proteins, as they stimulate the action of the amino acids to the brain and nervous system.

Onions, Rich Source of Quercetin

quercitin in onion skin

The onion is the richest dietary source of quercetin, a potent antioxidant flavonoid (also in shallots, yellow and red onions only but not in white onions), which is found on and near the skin and is particularly linked to the health benefits of onions.

Quercetin has been shown to thin the blood, lower cholesterol, raise good-type HDL cholesterol, ward off blood clots, fight asthma, chronic bronchitis, hay fever, diabetes, atherosclerosis and infections and is specifically linked to inhibiting human stomach cancer.

It's also an anti-inflammatory, antibiotic, antiviral, thought to have diverse anti-cancer powers. Quercetin is also a sedative. So far, there is no better food source of quercetin than onion skins.

You don't need to eat loads of onions to achieve these effects. In fact, studies show that you can reap the health benefits of onions by eating just one medium onion, raw or cooked, a day.

Detoxify Your Body with Onions

Onions contain a variety of organic sulphur compounds that provide health benefits. Sulphur-containing amino acids are found in onions as well as garlic and eggs.

These specific amino acids are called methionine and cystine and, among other things, they are very good at detoxifying your body from heavy metals.

In fact, they are able to latch on to mercury, cadmium and lead and escort them out of the body.

Vitamin C, also contained in onions, is excellent at detoxifying the body and is effective in removing lead, arsenic and cadmium. So increasing consumption of onions can help the body to get rid of these harmful metals.

Onions and the Heart

To help keep your blood free of clots, and make the most of the health benefits of onions, eat them both raw and cooked.

Prescribing onions for heart patients is hardly routine among cardiologists. But Harvard's Dr. Victor Gurewich advises all his patients with coronary heart disease to eat onions daily.

A large survey found that onions and garlic lovers had much better blood profiles (cholesterol, triglycerides and HDLs) than those who ate fewer of the bulbs or shunned them altogether.

Here are some of the things that onions can do for your heart:

  • Boost beneficial HDL cholesterol
  • Thin the blood
  • Retard blood clotting
  • Lower total blood cholesterol
  • Lower triglycerides
  • Lower blood pressure

Read more about the health benefits of onions for your heart

Cancer Prevention

different types of onions

One way the antioxidants in onions can protect you against cancer is by reducing the DNA damage in cells caused by free radicals, studies reveal.

All onions and onion relatives (garlic, leeks, chives and scallions, or spring onions) are rich in organosulphur compounds shown to help prevent cancer in lab animals.

In fact, an onion extract was found to destroy tumour cells in test tubes and to arrest tumour growth when tumour cells were implanted in rats.

The onion extract was shown to be unusually non-toxic, since a dose as high as forty times that of the dose required to kill the tumour cells had no adverse effect on the host.

In addition, shallots have been shown to exhibit significant activity against leukaemia in mice.

Other Health Benefits of Onions

Onions have also been shown to have a significant blood sugar-lowering action, even comparable to some prescription drugs.

The active compound that seems to be responsible for lowering glucose works by competing with insulin for breakdown sites in the liver, thereby increasing the life span of insulin.

Onions have historically been used to treat asthma, too. Its action in asthma is due to its ability to inhibit the production of compounds that cause the bronchial muscle to spasm and to relax bronchial muscle.

Onions have potent antibacterial activity, destroying many disease-causing pathogens, including E. coli and salmonella.

From one of my readers, Lynley Kempthorne:

Chop up a raw onion and cover it with honey (manuka honey is even better) and let it stand for four or five hours. It makes an excellent cough syrup and is wonderfully soothing for an inflamed throat.

Thank you Lynley

Quick Serving Suggestions:

roasted onions

The liberal use of onions and other bulbs of the same family, such as garlic, leeks and shallots, seems a particularly good idea considering their healing effects on the major degenerative diseases so common today, such as atherosclerosis, diabetes and cancer.

So try to enjoy the health benefits of onions as much as you can and to include them in your diet in every possible way.

Here are some quick serving ideas:

  • Onions can be eaten on their own steamed, boiled or roasted.
  • Sautéed chopped onions can be added to almost any vegetable dish to enhance its nutritional content and taste.
  • For an instant vegetarian chilli, heat together 1 medium chopped sautéed onion, with 12-oz/350 g. can of kidney beans, 12 oz/350 g. of chunky tomato sauce, and 2 tablespoons of olive oil, and season to taste with chili powder.
  • Chop 1 red onion, 2 medium tomatoes, 2 avocados and 1 jalapeño and combine together for an all-in-one guacamole salsa dip.
  • Place chunks of onion or small pearl onions on a skewer, either alone or with other vegetables, coat lightly with olive oil, and grill for approximately 10 minutes.

I hope you enjoyed reading about the health benefits of onions and I've managed to persuade you to make room for onions in your every day meals.

As you've seen, you don't need to eat a lot, but any amount will be extremely beneficial to your health.

Now that you've read the article, can you find the answer to these questions:

  • Can you name some of the nutrients contained in onions?
  • What causes the characteristic pungent aroma associated with onions that causes your eyes to water?
  • Why do onions mix well with protein?
  • What is quercetin, and what health benefits does it have?
  • Why are onions good at detoxifying the body of heavy metals?
  • What can onions do for the heart?
  • In what way do onions protect from cancer?
  • How do onions help lower blood sugar?

More articles on the Health Benefits of Onions and Garlic

Onions for Your Heart

Onions and Blood Pressure

The Incredible Health Benefits of Garlic

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Grow Your Own Onions

If you want some tips and advice on growing your own onions you must have a look at this beautiful website: : A how-to guide for growing vegetables in your backyard or containers; tips and advice about planting, maintaining, and harvesting your own vegetables, along with recipe ideas.


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