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Onions: Facts, Nutrition, Health Benefits, and More

Onions are a bulb vegetable that belongs to the same family as leeks, garlic, chives, and shallots. These aromatic vegetables belong to the genus Allium, and they are part of the lily family. Some even call onions “stinking lilies” because of their distinct and lingering smell.

Onions are one of the most widely cultivated vegetables that are a part of the Allium genus. While you may think onions only come in white, yellow, or red, there are several types of onions you may not be aware of. There are green onions, storage onions, sweet onions, spring onions, yellow, red, and white. Red onions got their name because their purple skin was at one time used to make red dyes.

Not only are onions popular all around the world, but they are one of the most nutritious vegetables as well. They are antibacterial and contain a wide variety of vitamins, minerals, and nutrients.

Nutrition Facts

Find out the specific nutrient profile of onions below to see how they can benefit your health.


Onions are packed with a variety of nutrients. The types of onions vary slightly in their nutrient profile as well. For example, while red raw onions contain 9.93 grams of carbohydrates, white raw onions provide 7.68 grams of carbohydrates.

Redraw onions also give the most amount of fiber compared to white and yellow onions. There is not a huge difference but red raw onions provide 2.2 grams of fiber, while white onions provide 1.2 grams of fiber and yellow onions give 1.9 grams of fiber.

The protein content is nearly identical to all onions ranging from .83 to .94 grams. All onions provide a wide variety of nutrition.

Vitamins & Minerals

All onions contain a similar amount of vitamins and minerals ranging from only a few milligrams to differentiate. All onions contain the minerals magnesium, phosphorus, calcium, iron, potassium, sodium, zinc, copper, manganese, iodine, and selenium. While white raw onions contain 21 mg of calcium, red raw onions provide 17 mg and white raw onions contain 15 mg of calcium.

The vitamins in red raw onions and yellow onions are impressive when it comes to vitamin C. These onions contain a whopping 8.4 mg of vitamin C or ascorbic acid. They also contain a healthy amount of vitamin B6 or pyridoxine and potassium. Vitamin B6, vitamin C, and potassium are essential vitamins necessary to protect the immune system and much more.

Vitamin B6 helps with storing sugar, fats, and protein in the body and it also helps with the development of the nervous system, skin, nails, and brain (1, 2). The body needs vitamin C to help form collagen, muscles, bone, and even blood vessels. Vitamin C is a crucial vitamin necessary to keep the immune system strong and avoid viruses and other illnesses as well. Potassium helps blood vessels contract and also regulates normal blood pressure. Potassium is also necessary to maintain adequate levels of fluid in the cells.

The vitamin content of onions can change with different cooking methods. The vitamins and mineral levels are measured using raw onions. Certain cooking levels and methods, such as high heat or using particular oils can have a drastic influence on the nutrient levels you are consuming. (3)


Onions can be a great part of a healthy nutritious diet because of their powerful vitamin and mineral content. Find out some surprising and fun facts below to learn more about this popular bulb vegetable.

Fun Facts

Onions are a bulb vegetable that has their fair share of fun facts along with a plethora of vitamins and minerals to improve your health.

Below are some fun facts about this popular, tear-jerking go-to vegetable.

  • Onion Juice is Antimicrobial: Onions may help fight bacteria.
  • Onions May Help Fight Against Antibiotic Resistance: Antibiotic resistance is a growing issue in America. Onions may be a crucial vegetable to help counter antibiotic resistance (4).
  • Onion consumption has increased 50% over the last two decades (5).
  • Onions Contain High Amounts of Sulfuric Compounds: Why should you care? That is the reason onions can make you cry when cutting them.
  • Onions were Discovered More than 5,000 Years Ago: They were first discovered in Central Asia and are one of the most ancient and beneficial food sources.
  • The United States is one of the top three producers of onions.
  • Onions have between eight and fifteen layers.

Health Benefits

What can onions do for your health? It turns out, quite a lot. Onions have natural antimicrobial properties. That means they fight off harmful bacteria rather than attracting them. Because of that and the many vitamins and minerals onions provide, there are many ways onions can benefit your health.

Onions May Lower Inflammation

Onions are a potent anti-inflammatory vegetable, much like many other vegetables in the same family and elsewhere. Vegetables in general are a crucial piece of a healthy diet to not only keep weight down but to lower inflammation and avoid disease. All disease is driven by too much inflammation in the body (6, 7).

The reason onions are so powerful at lowering inflammation is because they are full of vitamins, minerals, antioxidants, and special compounds that lower inflammation. Onions provide a range of therapeutic and pharmacological benefits. Eating more onions may help to lower oxidative stress in the body and they may even protect the immune system from disease (8).

There is even some research on how onions may help those who develop Covid-19. With so many unknowns after the pandemic, more research is emerging on how we can defend our bodies with quality nutrition and what may be the most helpful to fight off the virus. The study points to evidence saying that onions may not only be anti-inflammatory but also anti-viral and anti-thrombotic (9). Onions have been used for centuries as a part of medicinal treatment for many ailments. Although more research is necessary, onions may have a powerful benefit for the human body and disease prevention.

Onions May Reduce the Risk of Cancer

The benefits of onions and the entire Allium species may even range to cancer prevention. Onions, along with shallots, garlic, chives, and leeks may help to reduce the risk of cancer due to their nutritional profiles.

Although more research is necessary due to some conflicting information, there may be some benefits to consuming onions and reducing colorectal cancer, stomach cancer, esophageal cancer, prostate cancer, and potentially others as well (10).

Another reason garlic and onions may be a helpful aid to prevent cancer is that they have antimicrobial properties. Some studies suggest that sulfur compounds may slow or stop tumor growth (11).

Onions May Protect the Heart and Reduce the Risk of Hypertension

Since onions are an anti-inflammatory food, they may have a drastic medicinal effect on the heart. Due to their antioxidant properties and rich vitamin profile, onions may even help reduce the risk of high blood pressure or hypertension (12). Hypertension is one of the most common diseases in the United States, right behind heart disease.

Onions may even provide an overall improvement to blood lipid profiles, lowering triglycerides, reducing cholesterol, and lowering the risk of heart disease or heart attacks (13). Cardiovascular disease is the leading cause of death in the world. Adding a wide variety of nutrition to your everyday diet along with lifestyle changes can improve the chances of avoiding this common chronic disease.


Onions are a part of the Allium species and they include many different vegetables like garlic, shallots, and more. Their powerful nutrient profile makes them a beneficial addition to a healthy balanced diet.

With many vitamins, minerals, antioxidants, and compounds, onions may help to aid in heart health, reduce the risk of many types of cancer, and even lower inflammation in the body, helping to prevent many common diseases.

Adding onions to your diet from pickled onions to cooked, raw, and much more. See where you can start reaping the health benefits of onions in your diet today.