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Onions: Types, Health Benefits & Recipes

What is the first thing that comes to your mind when you think of onions? That it makes your eyes water, right? Onions produce a chemical irritant called propanethial S-oxide that stimulates the eyes' lachrymal glands, so they release tears.

Onions have a pungent taste and can be eaten either in cooked or raw form. Onions are also used in pickles and chutneys due to their strong taste.

Types Of Onions

1. Red onions - They are mild and sweet and can be eaten raw.

2. White onions - They are milder and sweeter than the yellow onions.

3. Yellow onions - They have white flesh with a brown or pale golden colour skin and have a strong sulfur-like aroma.

4. Shallots - They are smaller, have brown skin and purple colour flesh.

5. Scallions - They are also known as green onions or spring onions which are usually used in soups and sauces. Scallions have a milder taste than most onions.

Nutritional Value Of Onions

100 g of onions contain 89.11 g water, 40 kcal energy and they also contain

  • 1.10 g protein
  • 0.10 g fat
  • 9.34 g carbohydrate
  • 1.7 g fibre
  • 4.24 g sugar
  • 23 mg calcium
  • 0.21 mg iron
  • 10 mg magnesium
  • 29 mg phosphorus
  • 146 mg potassium
  • 4 mg sodium
  • 0.17 mg zinc
  • 7.4 mg vitamin C
  • 0.046 mg thiamine
  • 0.027 mg riboflavin
  • 0.116 mg niacin
  • 0.120 mg vitamin B6
  • 19 mcg folate
  • 2 IU vitamin A
  • 0.02 mg vitamin E
  • 0.4 mcg vitamin K

Health Benefits Of Onions

1. Improve heart health

Onions contain flavonoids that fight inflammation, lower cholesterol and triglyceride levels, thereby contributing to heart health. Quercetin, an antioxidant found in onions, lowers the risk of heart disease and lowers high blood pressure [1] .

According to the University of Maryland Medical Center, the quercetin in onions prevent plaque build-up in the arteries.

2. Lower blood sugar levels

Onions are known to lower blood sugar levels due to their sulphur compounds and quercetin. A 2014 study showed that patients with type 2 diabetes had normal liver enzymes and low glycemic levels when they ate sliced onions [2] .

3. Promote healthy digestion

Onions contain a type of soluble fibre called oligofructose, that acts as a food source for the beneficial bacteria in the intestines. This fibre when consumed helps your body maintain good levels of healthy bacteria. Onions prevent diarrhoea and constipation and thus promote healthy digestion [3] .

4. Prevent cancer

Red onions are the most common and effective ones in destroying breast and colon cancer cells. They contain high levels of quercetin and anthocyanin - the two compounds that provoke the cancer cells to kill themselves. These compounds make the environment unfavourable for cancer cells and this stops their growth [4] .

5. Boost the immune system

Onions contain vitamin C that strengthens the immune system and stimulates immune function. In addition, the polyphenols in onions work as antioxidants, which help protect the body against free radicals.

6. Maintain bone density

A research study shows that onions improve bone density in women who are going through or have completed menopause. Women who ate onions more often had a 20% lower risk of hip fracture than those who never ate onions [5] .

7. Prevent stomach ulcers

The quercetin in onions has the potential to fight against harmful bacteria like Escherichia coli (E. coli), Pseudomonas aeruginosa, Staphylococcus aureus (S. aureus) and Bacillus cereus. These kinds of bacteria are linked to stomach ulcers and certain digestive cancers [6] .

8. Reduce inflammation

The sulfur in onions possesses anti-inflammatory properties which can help lower inflammation [7] . Also, the quercetin in onions aids in relaxing the airway muscles and brings relief from asthma symptoms [8] .

9. Protect the eyes

Onions contain sulphur that is good for the eyes. It improves the health of the eyes by stimulating the production of a protein named glutathione, which acts as an antioxidant. This reduces the risk of eye diseases like glaucoma, cataracts, and macular degeneration. A study shows that onion juice cures conjunctivitis and blepharitis [9] .

10. Improve brain health

A research study shows that the sulfur content in onions, called di-n-propyl trisulfide, has a positive effect on memory impairment [10] . However, when onions are cooked, this sulfur compound gets destroyed. So, it's best to eat the onions raw.

Potential Health Risks Of Onions

According to the National Digestive Diseases Information Clearinghouse, the carbohydrate in onions may lead to bloating and gas. A study published in the American Journal of Gastroenterology, found that onions if consumed raw, could worsen heartburn in people suffering from chronic heartburn or gastric reflux disease [11] .

If you are on blood thinning medications, avoid having excess green onions as they interfere with blood thinning medicines. Also, if you are allergic to onions, avoid eating them.

Ways To Eat Onions

  • Combine cooked onions with other veggies for a healthy side dish.
  • Top meat dishes with sautéed onions.
  • Add caramelized onions to savoury baked goods.
  • Add sliced onions to your salad.
  • Use onion as a base for soups and stocks.
  • You can make home-made salsa with tomatoes, cilantro, and onions.
  • Use onions in egg dishes like omelette, frittatas, and quiches.

Onion Recipes

View Article References
  1. [1] Gabler, N. K., Osrowska, E., Imsic, M., Eagling, D. R., Jois, M., Tatham, B. G., & Dunshea, F. R. (2006). Dietary onion intake as part of a typical high fat diet improves indices of cardiovascular health using the mixed sex pig model.Plant foods for human nutrition,61(4), 179-185.
  2. [2] Akash, M. S. H., Rehman, K., & Chen, S. (2014). Spice plant Allium cepa: Dietary supplement for treatment of type 2 diabetes mellitus.Nutrition,30(10), 1128-1137.
  3. [3] Lewis, S., Burmeister, S., & Brazier, J. (2005). Effect of the prebiotic oligofructose on relapse of Clostridium difficile-associated diarrhea: a randomized, controlled study.Clinical Gastroenterology and Hepatology,3(5), 442-448.
  4. [4] Abdulmonem I. Murayyan, Cynthya M. Manohar, Gordon Hayward, Suresh Neethirajan.Antiproliferative activity of Ontario grown onions against colorectal adenocarcinoma cells.Food Research International, 2017; 96: 12
  5. [5] Matheson, E. M., Mainous III, A. G., & Carnemolla, M. A. (2009). The association between onion consumption and bone density in perimenopausal and postmenopausal non-Hispanic white women 50 years and older.Menopause,16(4), 756-759.
  6. [6] Sharma, K., Mahato, N., & Lee, Y. R. (2018). Systematic study on active compounds as antibacterial and antibiofilm agent in aging onions.Journal of food and drug analysis,26(2), 518-528.
  7. [7] Dorsch, W., Schneider, E., Bayer, T., Breu, W., & Wagner, H. (1990). Anti-inflammatory effects of onions: inhibition of chemotaxis of human polymorphonuclear leukocytes by thiosulfinates and cepaenes.International Archives of Allergy and Immunology,92(1), 39-42.
  8. [8] Townsend, E. A., & Emala, C. W., Sr (2013). Quercetin acutely relaxes airway smooth muscle and potentiates β-agonist-induced relaxation via dual phosphodiesterase inhibition of PLCβ and PDE4.American journal of physiology. Lung cellular and molecular physiology,305(5), L396–L403.
  9. [9] Nejabat, M., Salehi, A., Noorani Azad, P., & Ashraf, M. J. (2014). Effects of onion juice on the normal flora of eyelids and conjunctiva in an animal model.Jundishapur journal of microbiology,7(5), e9678.
  10. [10] Nishimura, H., Higuchi, O., Tateshita, K., Tomobe, K., Okuma, Y., & Nomura, Y. (2006). Antioxidative activity and ameliorative effects of memory impairment of sulfur‐containing compounds in Allium species.Biofactors,26(2), 135-146.
  11. [11] Allen, M. L., Mellow, M. H., Robinson, M. G., & Orr, W. C. (1990). The effect of raw onions on acid reflux and reflux symptoms.American Journal of Gastroenterology,85(4).
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Story first published: Friday, June 7, 2019, 15:20 [IST]