Are Onions Vegetables? (Full Answer Here)

The only ingredient that I find to be essential in a kitchen is the onion. Without onions, a stew or stir-fried dish would never be as delicious and we would be missing out on numerous health benefits.

Onions are members of the Allium genus of flowering plants that also includes garlic, shallots, leek, and chives. Because onions are an edible part of a plant, more specifically the bulb, they are technically considered vegetables. 

In this article, I’m going to explain in detail why onions are vegetables, why you should add them to your diet, and I’ll also speak on their nutritional content, as well as how you can add them to your diet.

Why Are Onions Vegetables?

Vegetables are generally sub-categorized according to the edible part of each plant, namely the leaves, stalks, roots, tubers, bulbs, and flowers. Onions are the edible bulbs of a plant. 

The definition of a fruit is the following: “In botany, a fruit is a seed-bearing structure in flowering plants formed from the ovary after flowering.” 

Based on that definition, we can comfortably assert that onions are not fruits, but vegetables. 

Interesting fact about onions:
Onions were worshiped by ancient Egyptians. They believed that its spherical shape and concentric rings symbolized eternity. They used to cover the tombs of their rulers with onion pictures and onions because they believed that would help the dead succeed in the afterlife.

Why Onions Should Be A Staple In Your Diet

Onions should be a staple in your diet because they can make your food tastier, and also provide you with numerous health benefits.

They were used in ancient times to treat ailments like headaches, heart disease, and mouth sores.

Here are some incredible health benefits of onions.

May Benefit Heart Health

Onions contain antioxidants and compounds that fight inflammation, decrease triglycerides, and reduce cholesterol levels, which may lower the risk of heart disease.

Onions contain high concentrations of a compound called Quercetin which is a potent anti-inflammatory that may help decrease heart disease risk factors such as high blood pressure.

Evidence on animal studies supports the assumption that onions may reduce the risk of heart disease, whether it’s inflammation, blood clot formation, or high triglyceride levels. (1, 2, 3)

Contain Cancer-Fighting Compounds

Onions contain sulfur compounds and flavonoid antioxidants, which are considered cancer-fighting properties according to studies.

In one study, people eating allium vegetables (of the same family as onions) were 22% less likely to be diagnosed with stomach cancer compared to those with the lowest intake. (4)

A review of 16 studies in more than 15,000 people found that participants with the highest onion intake had a 15% reduced risk of colorectal cancer compared to those with the lowest intake. (5)

Based on the existing evidence, these results are thanks to onions’ sulfur compounds and antioxidant properties.

Helps Control Blood Sugar

Specific compounds found in onions, namely quercetin and sulfur compounds, appear to possess anti-diabetic effects, according to studies.

Multiple studies with animals have shown that onion consumption may help regular blood sugar.

A study with 42 people with type 2 diabetes showed that eating 100 grams of fresh red onion reduced fasting blood sugar levels by about 40 mg/dl after four hours. (6)

May Improve Bone Density

Studies show that onion consumption is positively associated with improved bone mineral density, which is how doctors assess your risk of fracture taking into account diseases like osteoporosis.

A study in perimenopausal and postmenopausal women found that those drinking 100 ml of onion juice once a day, had a 5% greater overall bone density than those who drank onion juice with less frequency. (7)

The same study also revealed that older women were 20% less likely to suffer from a hip fracture compared to those who drank onion juice with less frequency.

May Improve Digestive Health

Not only are onions rich in fiber, but they also contain prebiotics, two properties/nutrients that are essential for optimal gut health.

Onions are rich in inulin and fructooligosaccharides, which are prebiotics that help increase the number of friendly bacteria in the gut, improving the immune system.

Eating prebiotics also helps increase the number of probiotics available in the gut, including the important Lactobacillus and bifidobacteria strains, which are crucial for digestive health.

Nutritional Content of Onions

Onions are very nutrient-dense, which means they’re low in calories but packed with micronutrients like vitamins and minerals, which is a quality that is common among vegetables.

One medium onion only has 44 calories but is considerably rich in vitamins, minerals, and fiber.

100 grams of raw onions contain the following nutrients:

  • Calories: 40 kcal
  • Protein: 1.1 grams
  • Carbs: 9.3 grams
  • Fat: 0.1 grams
  • Fiber: 1.7 grams
  • Vitamin C: 12% DV
  • Vitamin B6: 5% DV
  • Calcium: 2% DV
  • Magnesium: 2% DV

Onions are particularly high in Vitamin C, a nutrient that is essential in regulating immune health, collagen production, tissue repair, and iron absorption.

Vitamin C also acts as an antioxidant in the body and protects your cells against damage by free radicals, which are also referred to as unstable molecules.

By including onions in your meals, you’re essentially providing your body with the ability to better absorb iron, a nutrient that must be consumed adequately daily.

In other words, eat more onions, they are magnificent.

How to Eat More Onions

Onions are staples regardless of the culinary culture. They provide savory dishes with more depth and can be enjoyed cooked or raw (in a salad).

Here are a couple of ways in which you can include onions in your meals:

  • Add thinly sliced onions to a guacamole recipe to improve upon the flavor.
  • Sautée onions combined with other vegetables.
  • Add them as an ingredient in pizzas (whether at home or a restaurant).
  • Use onions (and garlic) as the base for a soup or any other dish.
  • Make a homemade salsa using onions, tomatoes, and cilantro.
  • Add caramelized onions on top of a nicely prepared veggie burger

As you can see, there are many ways in which you can implement onions, and there many more. Most recipes you’ll find online contain onions and garlic as the base of the recipe.


Onions are an edible part of a plant (the bulb), which means they’re technically vegetables.

However, I do understand that many people may find it confusing, especially when we think of tomatoes, eggplants, and pepper bells that are often regarded as vegetables but are in fact fruits.

Hopefully, this blog post has helped you demystify what onions are, and I also hope that by learning about the different benefits they provide, you maintain (or add) them as a staple in your diet.

Related Questions

Are Onions Easy to Grow?

Onions are a cold-season crop and are pretty easy to grow. If you can poke a hole in the ground, then you can easily grow onions, especially because they’re very sturdy vegetables.

This guide on how to grow onions is incredibly useful and the author makes it very easy for everyone.

How Long Do Onions Take To Grow?

According to authoritative websites like Savvy Gardening, onions take 90 days or more to reach maturity, but it also depends on the soil and whether or not you’re growing them indoors or outdoors.

Alexandre Valente

Hey there! My name is Alex and I've been vegan for more than five years! I've set up this blog because I'm really passionate about veganism and living a more eco-conscious life. Hopefully, I can use this website as a channel to help you out on your own journey!

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