health benefits of red onions

Onion is an indispensible ingredient in cuisines across the world. Onions are usually found in every kitchen but, often times, we do not give this superfood much thought. In fact: when we enlist superfoods having health benefits, rarely do we include red onions in it. It is time all this changes.

Apart from their special pungency and indispensability, it is time the world wakes up to the numerous health benefits of onions.

Onions are easily available, extremely versatile and can be used in hundreds of thousands of dishes. Compared to many expensive super foods, onions are also relatively cheaper.

In this guide, we will focus on the health benefits of red onions, the reasons that make them healthier and also touch upon a few buying, storing and cooking tips to help you make the most of their health benefits.

Why Are Red Onions Good for You?

Here are the highlights of health benefits of red onions:

  • Onions are an excellent source of vitamin C, vitamin B6, biotin, chromium, calcium and dietary fibre.
  • Red onions are rich in flavonoids which impart them their rich colour. These compounds act as antioxidants to stop tumours and also have immunity boosting properties.
  • The sulphur content in onions is particularly beneficial to the liver.
  • Sulphurous foods like onions are ideal for mixing with protein rich foods as they stimulate the action of amino acids.

These highlights indicate the main reasons why red onions are good for you.

Nutritional Value of Red Onions

It is recommended that to stay healthy you should eat an onion a day because onions are very nutritious.

  • Calories per serving (each serving size 1/2 cup or 80g cooked onion) -30 calories. Calories from fat- 0.
  • Total carbohydrate - 7 g
  • Sodium - 0 mg
  • Sugar - 3mg
  • Protein - 1 gram
  • Vitamin C - 10% daily value for 2000 calorie-per day diet
  • Calcium - 2 % daily value for a 2000-calorie per day diet

Health Benefits of Red Onions

1. Richest Source of Quercetin

  • Most onion varieties, and especially shallots and red onions are extremely rich in quercetin. This is a potent antioxidant located near the skin of the onion which helps lower bad cholesterol and also prevents blood clots.
  • Quercetin also increases good cholesterol and fights asthma. It is specifically linked to fighting stomach cancer.
  • Red onions are anti-inflammatory, anti-viral and antibiotic due to their quercetin content. They are also sedative in nature.

So far-there is no better food source of quercetin known to humans than red onions.

2. Detoxification Effect of Red Onions

  • The high organic sulphur content of red onions is beneficial for the liver and helps detoxify the body.
  • Sulphur containing amino acids like methionine and cystine found in red onions help chelate heavy metals from the body. These amino acids latch to heavy metals like mercury, chromium, lead and cadmium and literally escort them out of the body.
  • The high Vitamin C content of red onions also removes cadmium and arsenic from the body.

Increasing consumption of red onions can benefit the body by ridding it of these harmful chemicals.

3. Heart Benefits of Red Onions

  • Eating onions in any form-raw or cooked- can help clear blood clots and keep the heart healthy.
  • Apart from lowering bad cholesterol and increasing good cholesterol, red onions play following important heart-healthy roles : they keep the blood thin, retard blood clotting, lower triglycerdies and lower blood pressure.

Cardiologists often recommend onions to heart patients for these reasons.

4. Cancer Prevention

  • Many studies have proven that the antioxidants in red onions can help ward of cancerous tumours from forming in the body.
  • The organo-sulphur compounds (found in all onion varieties as well as its distant cousins like chives, garlic etc) have prevented cancer in lab animals. Onion extracts actually destroyed tumour cells in test tubes and thwarted tumour growth when planted in lab rats. The best part was: the extract was completely nontoxic and the dose nearly 40 times that required to kill cancer cells was found to have no adverse effect on the host.

5. Weight Loss Benefits of Red Onions

100 grams of onions contain only 44 calories which are mostly complex carbohydrates and this serving size provides you with 1.4 grams of dietary fibre. This indicates the health benefits of red onions for weight loss.

  • Red onions have significant blood sugar lowering action comparable to prescription drugs. There are many compounds present in red onions which lower glucose by competing with insulin for breakdown sites in the liver. This increases the lifespan of insulin in the blood.
  • The high water and fibre content of red onions can keep you full longer. As satiety increases, the food intake reduces.
  • The pungent odour of raw onions may put you off but it is totally worth it since their consumption can instil satiety and keep you full. While it is best to use sliced red onions in salads and sandwiches, you can also cook them in a variety of ways to reduce its pungency. Upon cooking red onion, you are left with a spicy sweet taste which makes it flexible for use in many recipes and cuisines. Cooked onions can be used for flavouring stews, soups, potatoes, meats, beans and many vegetarian or vegan dishes.

The best part of using onion in a weight loss diet is that its quercetin content is not reduced even when the onions are cooked. It is recommended that you use low heat method for making soups and stews with onions so as to preserve its antioxidant benefits.

6. Miscellaneous Health Benefit of Red Onions

  • Juice of red onion can be applied to hair and scalp to deter lice and dandruff.
  • The juice of red onion can also be applied to dark patches on the skin to remove tanning and make the skin tone even.
  • A small piece of onion inhaled can stop nose bleeds.
  • Sluggish digestion can be improved by increasing consumption of red onions.
  • Onions juice can cure insect bites and bee stings. The juice will burn the skin a bit, but after a while you will notice improvement in symptoms.
  • Onion juice is increasingly being used by herbalists and alternative medicine experts to heal all kinds of aches and pains. Even dentists recommend using onion juice to stop toothaches.
  • Certain kinds of warts and moles can be prevented and removed using onion juice regularly.
  • Keeping a piece of onion of the forehead can reduce fever.
  • They are particularly beneficial for bone health. A study conducted on rats showed that daily consumption of onions improved bone mass, bone thickness and bone mineral density. When consumed at the rate of 1 gram per day per 1 kg body weight, onions help inhibit bone reabsorption by 20%.

Why Are Red Onions Better Than White Onions?

Onions can be yellow, green or white, and there are nearly 500 varieties of onions available in nature. The taste of onions does not depend on its colour and they can be sweet tasting or savoury.

The red onion variety has a purple red colour skin with white flesh. They are medium to large in size. Their flavour is mild and sweet tasting. The texture is crisp which makes them a great addition to burgers. Red onions are fantastic to be eaten raw - add them to salads and you will get a wonderful colour. They can also be grilled lightly.

The answer to the question: are red onions healthier than white or yellow onions? The answer is yes, they are. Remember: colour in nature means health. The deeper and richer the colour of a fruit or vegetable, the more photochemicals, minerals and vitamins are present in it.

This is the main reason why red grapefruit is healthier than white grapefruit, purple cabbage is healthier than white cabbage and yellow and red onions are healthier than white onions.

Selecting and Storing Onions

You can buy onions all year round. These days, you can even buy them frozen. When buying fresh red onions; look for dry ones with small necks. The skin around the onions should be shiny and crackly in feel. Do not buy wet onions with wet, soft necks. Store the dry onion varieties in clean, dry and cool place. Never store onions with potatoes as they can cause each other to spoil rapidly.

Preparation Tips

  • To start with, remove the papery cover of the red onions. Remember, the antioxidants are concentrated in the layer closest to the onion’s skin. So avoid removing top layers and make sure you use these layers in your recipes.
  • Once an onion is cut and chopped, you can wrap the leftover in a plastic wrap and store the leftover in the refrigerator. It can last this way for up to a week.
  • To bake onions: remove the outermost cover. Chop the onion into ½ inch thick slices. Apply some cooking oil or spray on the baking/roasting pan. Preheat the oven to 400 F (200 deg C). Line the onion slices on the pan. Roast for 35 minutes or until browned.
  • To cook on stovetop- Heat a skillet and add some olive oil/coconut oil/butter/margarine or ghee. Add the sliced onions. Stir continuously and cover for few minutes until the onions are cooked. Cooking onions in this manner can take anywhere from 5-15 minutes depending on the thickness of the slices.
  • You can even Microwave the onions by placing them in a microwave-safe dish. Cover and cook on high for 5 minutes.

The health benefits of dietary consumption of onions have been reviewed and many studies are pointing to their organosulphur compounds and flavonoids like quercetin, both of which have been the focus of research pertaining to antioxidant activities, cancer prevention, as well a coronary heart diseases prevention.

More and more diets like paleo and ketogenic diet also rely on red onions for weight loss. Onions can improve lung function in asthamatics and also protect against infections and stomach cancer. Red onion varieties are extremely rich in concentration of health promoting phytochemicals.

This is the main reason why we must include red onions in our daily diet.

And if you wonder how to prepare and cook onions, here is a great video by Chef Buck. Enjoy!​

About the Author

Barbara is the founder and owner of She is a former research scientist with a serious passion for health. She enjoys writing about nutrition, wellness and lifestyle and empowering people to take control of their health.

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