Fact check: Are onions good for you?

Health benefits that make onions good for you (Image via Unsplash/Thomas Martinsen)
Health benefits that make onions good for you (Image via Unsplash/Thomas Martinsen)

Are onions good for you? Scientifically known as Allium cepa, they're bulb-shaped vegetables consumed across the world.

They're biologically related to chives, garlic, scallions, shallots and leeks. Onions are used as condiments across cuisines. These vegetables have been used in traditional medicines to treat digestion problems, including loss of appetite, upset stomach and gallbladder disorders. However, these benefits have not yet been established.

Although raw vegetables cannot be considered a cure for disorders, their health benefits can prevent several preventable diseases. In this article, we will analyze the nutritional properties and health benefits that make onions good for you.


Is onion good for you? Nutrition facts

Antioxidant compounds make onions good for you. (Image via Unsplash/K8)
Antioxidant compounds make onions good for you. (Image via Unsplash/K8)

According to the U.S. Department of Agriculture, hundred grams of raw onions provide:

  • Calories: 40 kcal
  • Water: 89%
  • Protein: 1.1 grams
  • Carbs: 9.3 grams
  • Sugar: 4.2 grams
  • Fiber: 1.7 grams
  • Fat: 0.1 grams

When we take a closer look at the nutritional table, we notice that onions do not contain significant amounts of macronutrients. It's the micronutrients that make onions good for you.


Benefits of having onions

Onions also contain significant amounts of other categories of nutrients, including vitamins, minerals and antioxidants, like:

  • Vitamin C: It's a natural antioxidant that makes the immune system strong. Most fruits and vegetables contain ascorbic acid in varying amounts.
  • Folate (B9): It's a water-soluble vitamin, also known as folic acid. Folate is essential for various functions, especially in pregnant women.
  • Vitamin B6: This essential vitamin helps in red blood cell formation.
  • Potassium: Potassium is known for its blood pressure-lowering effects. This mineral is also beneficial for heart health.

Beneficial plant compounds in onions are known for their antioxidant activities. These compounds are being studied extensively for their medicinal properties. Some of the most important naturally occurring compounds that make onions good for you are:

  • Anthocyanins: Found exclusively in red and purple onions, these compounds have strong antioxidant properties.
  • Quercetin: It's a type of flavonoid that helps lower blood pressure and improve heart health.
  • Sulfur compounds: These compounds may protect against cancer.
  • Thiosulfinates: These sulphur-containing compounds can improve immunity and fight pathogens.

All types of onions, including green onions, scallions, and chives, contain these compounds in varying quantities, except for anthocyanins, which are absent in green onions and chives.

These compounds give the characteristic red color to certain varieties. All these naturally occurring compounds make onions good for you.


Benefits of raw onion

Anthocyanins make onions good for you (Image via Unsplash/Burhan Rexhepi)
Anthocyanins make onions good for you (Image via Unsplash/Burhan Rexhepi)

Heat destroys essential vitamins and antioxidant compounds, and cooking onions can reduce their nutritive value.

Consuming onions as a salad can provide more beneficial compounds than cooked onions. The mild and subtle flavor of certain varieties make onions good for you. You can include greener varieties, including scallions in soups, stews and steamed meals without cooking them. Keep in mind that raw onions also contain anti-nutrients and can reduce absorption of nutrients.

Raw onion paste and onion water are also known to promote hair growth and reduce hair loss. Organic acids, including glutamic, oxalic, pyruvic, malic, tartaric, citric and fumaric acids present in onions can reduce dandruff level significantly. However, it's advisable to speak to a dermatologist if you have a scalp infection or severe dandruff.


Are red onions good for you? A comparative analysis

Red onions contain fructooligosaccharides, compounds that act as prebiotics and promote gut health.

These onions have a strong flavor and are believed to contain more amounts of certain natural compounds. It has to be kept in mind that they also contain high amounts of anti-nutritional factors and might reduce the absorption of certain vitamins and minerals. However, it's the versatility of this vegetable that makes red onions good for you.


Indranil Biswas is a nutritionist and personal trainer with a diploma in dietetics and personal training with a specialization in sports nutrition and strength training.


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