What are the Health Benefits of Eating Onions every day?

Last updated on April 21st, 2023 at 05:39 pm

10 minutes read.  


In this article:

Nutrition facts

Health Benefits

Recipe tips



Onions are the common vegetables used in our kitchen virtually every day.

Onions can be consumed fresh, cooked, fried, and can be added to some processed food.

Daily consumption of onions has been shown to reduce the risk of cancer, cataract, DNA damage, and vascular and heart diseases.

Very important to know, the presence of onions and garlic in pan-fried/cooked meat has been shown to reduce the formation of carcinogenic heterocyclic amines and azaarenes in cooked meat.

Onions are excellent sources of vitamin C, sulphuric compounds, flavonoids, and phytochemicals.”

Phytochemicals, or phytonutrients, are naturally occurring curative compounds in fruits and vegetables that are able to react with the human body to trigger healthy reactions.

Flavonoids are responsible for pigments in many fruits and vegetables. Studies have shown that they may help reduce the risk of Parkinson’s disease, cardiovascular disease, and stroke. (1, 2, 3, 4, 5 )

In fact, the medicinal properties of onions have been recognized since ancient times, when they were used to treat ailments like headaches, heart disease, digestive problems, scorpion stings, and mouth sores (6)

In this article, you will learn all the research-proven health benefits of onions and how to maximize its benefits for yourself and your family.

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Nutrition facts about onions

Here are the nutrition facts for raw onions, according to the U.S. Food and Drug Administration, which regulates food labeling through the National Labeling and Education Act. (7)

Serving size: 1 medium onion (5.3 oz / 148 g)

Calories: 45 (Calories from Fat: 0)

Total fat: 0g (0%)

Total Carbohydrate: 11g (4%)

Dietary Fiber: 3g (12%)

Sugars: 9g

Cholesterol: 0mg (0%)

 Sodium: 5mg (0%)

Potassium: 190mg (5%)

 Protein: 1g

Vitamin A: (0%)

Vitamin C: (20%)

Calcium: (4%)

Iron: (4%)

Amount per serving (%DV*) *Percent Daily Values (%DV) are based on a 2,000-calorie diet.

Other important phytochemicals in onions are disulfides, trisulfides, cepaene, and vinyldithiins. They all are helpful in maintaining good health and have anticancer and antimicrobial properties, according to the National Onion Association. (8, 9)

Health Benefits of eating onions every day

1. Very rich in antioxidants

Antioxidants are compounds that inhibit oxidation, a process that leads to cellular damage and contributes to diseases like cancer, diabetes, and heart disease. (10)

One study that analyzed the antioxidant contents of six different types of onions found that most layers of onions contain higher antioxidant compounds than the middle and inner layers.

Unfortunately, these outer layers are generally discarded by the consumers thus depriving them of important health-promoting phytochemicals. (11)

Onions are an excellent source of antioxidants. In fact, they contain at least 17 different varieties of flavonoid antioxidants. (12)

Red onions, in particular, contain anthocyanins, which are plant pigments in the flavonoid family that give red onions their deep color.

Multiple population studies have found that people who consume more foods rich in anthocyanins have a reduced risk of heart disease.

For example, a study of 43,880 males showed that habitual intakes as high as 613 mg per day of anthocyanins were correlated to a 14% lower risk of nonfatal heart attacks. (13)

Similarly, a 2018 review concluded that consuming higher amounts of anthocyanin-rich foods was associated with a lower risk of heart disease and heart disease mortality. (14)

Additionally, anthocyanins have been found to protect against certain types of cancer and diabetes. (15, 16)

2. Very rich in nutrients

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

One medium onion has just 44 calories but delivers a considerable dose of vitamins, minerals, and fiber. (17)

This vegetable is particularly high in vitamin C , a nutrient involved in regulating immune health, collagen production, tissue repair, and iron absorption.

Vitamin C also acts as a powerful antioxidant in your body, protecting your cells against damage caused by unstable molecules called free radicals. (18)

Onions are also rich in B vitamins, including folate and vitamin B6 — which play key roles in metabolism, red blood cell production, and nerve function. (19)

They’re a good source of potassium, a mineral that many people are lacking.

In fact, the average potassium intake of Americans is less than half the recommended daily value (DV) of 4,700 milligrams (mg). (20)

Normal cellular function, fluid balance, nerve transmission, kidney function, and muscle contraction all require potassium. (21)

3. May benefit heart health

Onions contain antioxidants and compounds that fight inflammation, decrease triglycerides, and reduce cholesterol levels, consequently, daily consumption of onions may protect you from heart disease risk if all other unhealthy diets are kept in moderation or if possible avoided.

Their potent anti-inflammatory properties may also help reduce high blood pressure and protect against blood clots.

Quercetin is a flavonoid antioxidant that’s highly concentrated in onions. Since it’s a potent anti-inflammatory, it may help decrease heart disease risk factors, such as high blood pressure. (22)

A study in 70 people with overweight and high blood pressure found that a dose of 162 mg per day of quercetin-rich onion extract significantly reduced systolic blood pressure by 3–6 millimeters of mercury (mmHg), compared to a placebo. (23)

Onions have also been shown to decrease cholesterol levels.

A 2014 study of 54 females with polycystic ovarian syndrome (PCOS) found that consuming large amounts of raw red onions (80–120 grams per day) for 8 weeks reduced total and LDL (bad) cholesterol compared to a control group. (24)

Additionally, evidence from animal studies supports that onion consumption may reduce risk factors for heart disease, including inflammation, high triglyceride levels, and blood clot formation. (25, 26, 27)

4. Contain anti-cancer compounds

Eating vegetables of the Allium genus like garlic and onions has been linked to a lower risk of certain types of cancer, including stomach and colorectal cancer.

A review of 26 studies showed that people who consumed the highest amount of allium vegetables were 22% less likely to be diagnosed with stomach cancer than those who consumed the lowest amount. (28)

Moreover, a 2014 review of 16 studies in 13,333 people demonstrated that those with the highest onion intake had a 15% reduced risk of colorectal cancer compared to those with the lowest intake. (29)

These cancer-fighting properties have been linked to the sulfur compounds and flavonoid antioxidants found in allium vegetables.

For example, onions provide onionin A, a sulfur-containing compound that has been shown to decrease tumor development and slow the spread of ovarian and lung cancer in test-tube studies. (30, 31)

Onions also contain fisetin and quercetin, which are flavonoid antioxidants that may inhibit tumor growth. (32, 33).

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5. Help control blood sugar

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

An older study in 42 people with type 2 diabetes demonstrated that eating 3.5 ounces (oz), or 100 grams, of raw red onion, significantly reduced fasting blood sugar levels after 4 hours. (34 )

Additionally, multiple animal studies have shown that onion consumption may benefit blood sugar control.

A study showed that rats with diabetes fed food containing 5% dried onion powder for 8 weeks experienced decreased fasting blood sugar levels and had lower triglyceride and cholesterol levels compared to a control group. (35)

Specific compounds found in onions, such as quercetin and sulfur compounds, also possess antidiabetic effects.

For example, quercetin has been shown to interact with cells in the small intestine, pancreas, skeletal muscle, fat tissue, and liver to control whole-body blood sugar regulation. (36)

Related: How to Use Onions Skin to prepare varieties of Food

Related: What are the medicinal uses of White Onions?

6. May boost bone density

Though dairy gets much of the credit for boosting bone health, many other foods, including onions, may help support strong bones.

A study of 24 middle-aged and postmenopausal females showed that those who consumed 3.4 oz (100 milliliters) of onion juice daily for 8 weeks had improved bone mineral density and antioxidant activity compared to a control group. (37)

Another older study in 507 perimenopausal and postmenopausal females found that those who ate onions at least once a day had a 5% greater overall bone density than individuals who ate them once a month or less. (38)

Plus, the study demonstrated that older individuals who most frequently ate onions decreased their risk of hip fracture by more than 20% compared to those who never ate them. (38)

It’s believed that onions help reduce oxidative stress, boost antioxidant levels, and decrease bone loss, which may prevent osteoporosis and boost bone density. (39)

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7. Have antibacterial properties

Onions can fight potentially dangerous bacteria, such as Escherichia coli (E. coli), Pseudomonas aeruginosa, Staphylococcus aureus (S. aureus), and Bacillus cereus. (40, 41)

Furthermore, onion extract has been shown to inhibit the growth of Vibrio cholera, a bacteria that is a major public health concern in some parts of the world. (42)

Quercetin extracted from onions seems to be a particularly powerful way to reduce the growth of bacteria.

Some test-tube studies suggest that quercetin could inhibit the growth of several strains of bacteria, including Helicobacter pylori (H. pylori), a type of bacteria associated with stomach ulcers and certain digestive cancers. (43, 44)

Another test-tube study found that quercetin damaged the cell walls and membranes of E. coli and S. aureus. (45)

8. May boost digestive health

Onions are a rich source of fiber and prebiotics, which are necessary for optimal gut health.

Prebiotics are non-digestible types of fiber that are broken down by beneficial gut bacteria.

Gut bacteria feed on prebiotics and create short-chain fatty acids — including acetate, propionate, and butyrate.

Research has shown that these short-chain fatty acids strengthen gut health, boost immunity, reduce inflammation, and enhance digestion. (46, 47)

Additionally, consuming foods rich in prebiotics help increase probiotics, such as Lactobacillus and bifidobacteria strains, which benefit digestive health. (48)

A diet rich in prebiotics may help improve the absorption of important minerals like calcium, which may improve bone health.  (49)

Onions are particularly rich in the prebiotics inulin and fructooligosaccharides. These help increase the number of friendly bacteria in your gut and improve immune function. (50)

Other forks medicinal uses of onions.

In some parts of Africa such as the Igbos, onions are used to treat the painful effect of scorpion stings. It also prevents the scorpion venom from entering the bloodstream.

How to add onions to your diet

Onions are a staple in kitchens around the world.

They give flavor to savory dishes and can be enjoyed either raw or cooked.

Not to mention, they can boost your intake of fiber, vitamins, and minerals.

Recipe tips

Here are different tips on how to add onions to your diet:

  • Use raw onions to add a kick of flavor to your guacamole recipe.
  • Add caramelized onions to savory baked goods.
  • Combine cooked onions with other vegetables for a healthy side dish.
  • Try adding cooked onions to egg dishes , such as omelets, frittatas, or quiches.
  • Top meat, chicken, or tofu with sautéed onions.
  • Use fresh onions to eat roasted meat (the popular suya), and dried or fried meat.
  • Spread sliced fresh onions abacha agworoagwo , nkwobi(porridge goat head meat), ugba (sliced fermented porridge oil beans seed)
  • Spread fresh onions on porridge beans.

Adding fresh onions or half-done onions to your diet helps to promote smooth digestion.  Try it and pay attention to know how smoothly your digestive system will function after the meal.

  • Add thinly sliced red onions to your favorite salad.
  • Make a fiber-rich salad with chickpeas, chopped onions, and red peppers.
  • Use onion and garlic as a base for stocks and soups.
  • Throw onions into stir-fry dishes.
  • Top tacos, fajitas, and other Mexican dishes with chopped raw onions.
  • Make a homemade salsa with onions, tomatoes, and fresh cilantro.
  • Prepare a hearty onion and vegetable soup.
  • Add onions to chili recipes for a flavor boost.
  • Blend raw onions with fresh herbs, vinegar, and olive oil for a tasty homemade salad dressing.


 The health benefits related to onions are quite impressive. These nutrient-packed vegetables contain powerful compounds that may decrease your risk of heart disease and certain cancers.

Onions have antibacterial properties and promote digestive health, which may improve immune function. What’s more, they’re versatile and can be used to heighten the flavor of any savory dish.

Adding more onions to your diet is an easy way to benefit your overall health.

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