Nutritional value of onions, Health benefits and Side effects


Onions are round bulb vegetable that is from the Allium CAPA genus of plants, also known as the bulb onion or common onion. It is a vegetable that is the most widely cultivated species of its family. This may be because it is heavily packed with nutrients and have so many health benefits.

Onions close relatives include garlic, scallion, shallot, leek, chive, and Chinese onion.

The nutritional value of onions cannot be overemphasized as it has been used in herbal medicines all around the world for centuries and is still in use for today’s modern medicine and used in different cuisines.


Onions come in varieties; there are red onions, white onions, spring onions, and brown onions and shallots.

Did you know that there are only slight differences in the nutritional value of onions and in the taste of these different types of onions? In fact, the red onion is considered the most powerful (nutritional) of them all. This is because of its deep savoury taste.

Onions can be eaten raw, used in frying, fried and eaten, used in cooking virtually any dish that requires a savoury taste. In West Africa, most foods are cooked with onions.

The nutritional value of onions when eaten raw is as follows:

Nutritional value of onions per 100 g (3.5 oz)

Nutrient Value
Energy166 kJ (40 kcal)
Carbohydrates9.34 g
Sugars4.24 g
Dietary fiber1.7 g
Fat0.1 g
Protein1.1 g
Thiamine (B1)4% 0.046 mg
Riboflavin (B2)2% 0.027 mg
Niacin (B3)1% 0.116 mg
Pantothenic acid (B5)2% 0.123 mg
Vitamin B69% 0.12 mg
Folate (B9)5% 19 μg
Vitamin C9% 7.4 mg
Calcium2% 23 mg
Iron2% 0.21 mg
Magnesium3% 10 mg
Manganese6% 0.129 mg
Phosphorus4% 29 mg
Potassium3% 146 mg
Zinc2% 0.17 mg
Other constituents:
Water89.11 g
Fluoride1.1 µg

Health Benefits of Onions

  • When taken by mouth: Onion is LIKELY SAFE when taken by mouth in amounts commonly found in food. Onion extract is POSSIBLY SAFE for most people when taken by mouth as a medicine. Daily doses of up to 900 mg of onion extract have been safely used for 12 weeks. Side effects might include stomach distress or pain after eating onion. The nutritional value of Onions is most active when eaten raw
  • When applied to the skin: Onion extract is safe when applied to the skin. Side effects might include skin irritation or eczema following skin contact with onion. I won’t advise this method if you want to get the most out of the nutritional value of Onions
  • When applied on hair: Onions accelerates hair growth, stops breaking of hair, and adds the required acid to hair. This is one of the most nutritional values of onions as many women (and men) find onions useful than behind- the- counter hair products.

Side effects of onions

Onions are very potent and have many side effects and interactions with medicines so one needs to be careful while using it.

The following are side effects of Onions;

  • Pregnancy and breast-feeding: There is not enough reliable information to know if the onion is safe to use as a medicine when pregnant or breast-feeding. Stay on the safe side and avoid using onion in amounts larger than usual food amounts.
  • Bleeding disorder: Onion might slow blood clotting. There is concern that onion might increase the risk of bleeding when taken as a medicine. Do not use medicinal amounts of onion or onion extract if you have a bleeding disorder.
  • Cross-allergens: People with allergies to mugwort and celery might also be allergic to onion. Do not use medicinal amounts if you have these allergies.
  • Diabetes: Onion might lower blood sugar. If you have diabetes and use onion in medicinal amounts, check your blood sugar carefully.
  • Surgery to place a pouch near the anus (ileal pouch-anal anastomosis): People that have had surgery to place a pouch near the anus might find that onion increases feelings of gas. Do not eat large amounts of onion if you have had this surgery.
  • Indigestion: People that experience indigestion often finds that eating onion increases symptoms. Do not eat large amounts of onion if it increases your symptoms.
  • Surgery: Onion might slow blood clotting and lower blood sugar. In theory, onion might increase the risk of bleeding or interfere with blood sugar control during and after surgical procedures. Stop using onion as a medicine at least 2 weeks before a scheduled surgery.

Interactions of onions with medicines

Aspirin interacts with ONION

Some people are allergic to onions. Aspirin might increase your sensitivity to onions if you are allergic to onions. This has only been reported in one person. However, to be on the safe side, if you are allergic to onions do not take aspirin and eat onions.

Lithium interacts with ONION

Onion might have an effect like a water pill or “diuretic.” Taking onion might decrease how well the body gets rid of lithium. This could increase how much lithium is in the body and result in serious side effects. Talk with your healthcare provider before using this product if you are taking lithium. Your lithium dose might need to be changed.

Medications for diabetes (Antidiabetes drugs) interacts with ONION

Onion might decrease blood sugar. Diabetes medications are also used to lower blood sugar. Taking onion along with diabetes medications might cause your blood sugar to go too low. Monitor your blood sugar closely. The dose of your diabetes medication might need to be changed.

Some medications used for diabetes include glimepiride (Amaryl), glyburide (DiaBeta, Glynase PresTab, and Micronase), insulin, pioglitazone (Actos), rosiglitazone (Avandia), chlorpropamide (Diabinese), glipizide (Glucotrol), tolbutamide (Orinase), and others.

Medications that slow blood clotting (Anticoagulant / Antiplatelet drugs) interacts with ONION

Onion might slow blood clotting. Taking onion along with medications that also slow clotting might increase the chances of bruising and bleeding.

Some medications that slow blood clotting include aspirin, clopidogrel (Plavix), diclofenac (Voltaren, Cataflam, others), ibuprofen (Advil, Motrin, others), naproxen (Anaprox, Naprosyn, others), dalteparin (Fragm

Nutritional value of onions



How useful was this post?

Click on a star to rate it!

As you found this post useful...

Follow us on social media!

We are sorry that this post was not useful for you!

Let us improve this post!

Tell us how we can improve this post?

Avatar of Isreal Olabanji DST RN
Isreal Olabanji DST RN
Am Isreal olabanji a dental assistant and public health professionals and has years of experience in assisting the dentist with all sorts of dental issues. We regularly post timely and trustworthy medical information and news. My goal is to enlighten everyone in all aspects of health towards participating in fitness, Dental care, healthy recipes, child health, obstetrics, and more.

Stay in Touch

Follow the leading source for trustworthy and timely oral health and medical news and information. Providing credible health information. Start changing your life today!

Related Articles

error: Alert: Content is protected !!