7 Amazing Health Benefits of Onions

Onions belong to the Allium genus of plants and are closely related to garlic, leeks, and shallots. There are many varieties of onions, including red, yellow, purple, white, Spanish, and Vidalia onions. Most people consume 20 pounds of onions per year in various forms — raw, cooked, pickled, or powdered.

These vegetables give flavor to dishes and can be eaten raw or cooked. More importantly, onions contain vitamins, minerals, and plant compounds that promote health in many ways. In this post, we will discuss seven impressive health benefits of onions.

Health Benefits of Onions

1. Loaded with Nutrients

Types of OnionsOnions are nutrient-dense, low in calories, but rich in vitamins and minerals. One onion only has 44 calories but contains a considerable amount of vitamins, minerals, and fiber.

They contain vitamin C, which is involved in the body’s immune system, tissue repair, collagen production, and iron absorption. Vitamin C acts as a powerful antioxidant, protecting cells against damage caused by free radicals.

Onions also contain B vitamins, including pyridoxine (B6) and folate (B9), which play important roles in metabolism, nerve function, and red blood cell production.

Moreover, onions are a good source of potassium. Body functions such as nerve transmission, kidney function, fluid balance, and muscle contraction all require potassium.

2. May Benefit Heart Health

Onions contain compounds and antioxidants that fight inflammation, decrease triglycerides, and reduce the level of cholesterol in the body — all of which may lower the risk of heart disease.

Their anti-inflammatory properties can help reduce blood pressure and prevent blood clots. Onions contain organic sulfur compounds, which are responsible for their strong taste and smell. Organic sulfur compounds help lower the cholesterol levels in the body and may help break down blood clots, reducing the risk of heart disease and stroke.

3. May Boost Digestive Health

Red OnionsOnions are a good source of prebiotics, which are necessary for gut health. Prebiotics are a non-digestible type of fiber that are broken down by good bacteria in the gut. These gut bacteria create short-chain fatty acids, including acetate, butyrate, and propionate. Research shows that these short-chain fatty acids promote gut health, boost immunity, and enhance digestion.

Eating foods rich in prebiotics also helps increase probiotics, such as bifidobacteria and Lactobacillus strains, which benefit digestive health.

A diet rich in prebiotics can help in the absorption of minerals such as calcium, which is important for bone health. Onions are especially rich in the prebiotics fructooligosaccharides and inulin. These help increase the friendly bacteria in the gut and also improve immune function.

4. Rich in Antioxidants

Antioxidants are compounds that prevent oxidation, which causes cellular damage and contributes to diseases such as cancer, diabetes, and heart disease.

Onions are rich in plant compounds such as flavonoids, which have antioxidant and anti-inflammatory properties. These compounds, when consumed on a regular and sufficient basis, may help protect against chronic illnesses such as cancer and diabetes. In fact, onions contain over 25 kinds of flavonoids, making them a good source of antioxidants.

Also, onions contain sulfur-containing compounds, which have been shown to protect against certain cancers.

5. Contain Cancer-Fighting Compounds

Eating allium vegetables like onions and garlic has been associated with a lower risk of certain cancers, including colorectal and stomach cancer.

Based on a review of 26 studies, those who eat the most allium vegetables had a 22% lower risk of developing stomach cancer than those who consumed the least.

In addition, a review of 16 studies involving 13,333 participants revealed that those who consumed the most onions had a 15% lower risk of colon cancer than those who consumed the least.

Allium veggies contain flavonoid antioxidants and sulfur compounds that have been linked to these anti-cancer properties.

6. Help Control Blood Sugar

Onions can help control blood sugar, which is significant for those with diabetes or prediabetes. A study conducted on people with type 2 diabetes showed that eating 100 grams of fresh red onion decreased fasting blood sugar by about 40 mg/dl after four hours.

Compounds found in onions like quercetin and sulfur compounds may have anti-diabetic effects. Quercetin interacts with cells in the pancreas, small intestine, fat tissue, and liver to regulate blood sugar in the body.

7. Have Antibacterial Properties

Onions can help fight dangerous bacteria, such as Pseudomonas aeruginosa, S. aureus, Bacillus cereus, and E. coli. Also, onion extract has been found to inhibit Vibrio cholerae, a bacteria that’s a major health concern in the developing world.

How to Add Onions to Your Diet

  • Combine cooked onions and other vegetables to make a side dish.
  • Add cooked onions to vegan egg dishes (omelets, frittatas or quiches).
  • Throw onions into stir-fry dishes.
  • Add thinly-sliced onions to your favorite salad.
  • Make a fiber-rich salad with chopped onions, chickpeas, and red peppers.
  • Prepare an onion and vegetable soup.
  • Use garlic and onion as a base for stocks and soups.
  • Add caramelized onions on savory baked goods.
  • Top vegan tacos and other Mexican dishes with chopped onions.
  • For a flavor boost, add onions to vegan chili recipes.
  • Make a homemade salsa with onions, fresh cilantro, and tomatoes.
  • Blend raw onions with herbs, vinegar and olive oil to make tasty salad dressing.


The health benefits of onions are quite impressive. Onions contain compounds that may reduce your risk for heart disease and certain cancers. These vegetables have antibacterial properties and also promote digestive health. Lastly, they’re versatile and can be used to enhance the flavor of any dish.

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