Vegetables rich in nutrients, onions may help regulate blood sugar, strengthen bones, and improve heart health, among other things.

Garlic, shallots, and leeks are among the flowering plants in the Allium genus, which includes onions.

They have a lot of beneficial vitamins, minerals, and plant compounds in addition to being tasty, adaptable, and reasonably priced.

The medicinal properties of onions have been recognized for thousands of yearsTrusted Source. Athletes in ancient Greece supposedly used onions to purify their blood, while medieval and traditional doctors prescribed them to help treat headaches, heart disease, and mouth sores.

Below are  5 health benefits of onions

Packed with nutrients

Onions are nutrient-dense, meaning they’re low in calories but high in vitamins, fiber, and minerals.

One medium onion (110 grams [g]) contains:

Calories: 44

Protein: 1.2 g

Carbs: 10.3 g

Sugar: 4.7 g

Fiber: 1.9 g

Fat: 0.1 g

Potassium: 3.4% of Daily Value (DV)

Vitamin C: 9% of the DV

Onions are high in vitamin C, which may help regulate your immune health, collagen production, and iron absorption.

It’s also a powerful antioxidant that could help protect your cells from unstable, damaging molecules called free radicals.

Onions are rich in B vitamins, including folate and vitamin B6. These play key roles in metabolism, red blood cell production, and nerve function.

Lastly, onions are a good source of potassium, a mineral that may help withTrusted Source:

May benefit heart health

Onions contain antioxidants and compounds that may reduce your risk of heart disease by fighting inflammation and lowering triglyceride and cholesterol levels.

They contain a large amount of quercetin, a flavonoid antioxidant and anti-inflammatory that may help lower high blood pressure.

A small 2015 study in 70 people with overweight and hypertension suggests that a daily dose of 162 mg of quercetin-rich onion extract may significantly reduce systolic blood pressure by 3.6 millimeters of mercury.

Also, a small 2014 study in 54 females with polycystic ovary syndrome found that consuming 80–120 g of raw red onions per day for 8 weeks lowered total and LDL (bad) cholesterol levels.

Loaded with antioxidants

Antioxidants are compounds that inhibit oxidation, a process that may lead to cellular damage and contribute to diseases such as cancer, diabetes, and heart disease.

Onions are an excellent source of antioxidants and contain at least 17 types of flavonoids.

Red onions, in particular, contain anthocyanins, plant pigments in the flavonoid family that give red onions their deep color. These may protect against diabetes and certain types of cancerTrusted Source.

In a 2016 study involving 43,880 males, researchers found that habitual anthocyanin intakes up to 613 mg were correlated with a 14% lower risk of nonfatal heart attacks.

Similarly, the authors of a 2019 review concluded that consuming more anthocyanin-rich foods was associated with a lower risk of heart disease and of death from heart disease.

Contain anticancer compounds

Allium vegetables such as onions and garlic may lower your risk of developing certain types of cancer, including stomach and colorectal cancers.

In a 2015 review of 26 studies, researchers concluded that people who consumed the most allium vegetables were 22% less likely to receive a diagnosis of stomach cancer than those who consumed the least.

And in a 2014 review of 16 studies involving a total of 13,333 people, researchers suggested that people with the greatest onion intake had a 15% lower risk of colorectal cancer than those with the lowest intake.

Test-tube studies suggest that onionin A, a sulfur-containing compound in onions, may help decrease tumor development and slow the spread of ovarian cancer.

Onions also contain fisetinTrusted Source and quercetinTrusted Source, which are flavonoid antioxidants that may inhibit tumor growth.

Help regulate blood sugar

Eating onions may help regulate blood sugar levels, which is significant for people with diabetes or prediabetes.

A small 2010 study in 84 people with type 1 or type 2 diabetes found that eating 100 g of raw red onion significantly reduced fasting blood sugar levels after 4 hours.

A 2020 study showed that rats with diabetes who ate food containing 5% dried onion powder for 8 weeks had decreased fasting blood sugar levels and lower triglyceride and cholesterol levels than a control group.

Quercetin has also been shown to help regulate whole-body blood sugar balance by interacting with cells in the: