although all vegetables are important for health, certain species have unique benefits.
onions are members of the flowering plant allium genus, which also includes garlic, shallots, leeks, and chives.
these vegetables contain a variety of vitamins, minerals, and potent plant compounds that have been shown to promote health in several ways.
in fact, the medicinal properties of onions have been recognized since ancient times, when they were used to treat diseases such as headaches, heart disease, and mouth ulcers. (1）。
here are 9 impressive health benefits of onions.
1. rich in nutrients
onions are rich in nutrients, which means they are low in calories but high in vitamins and minerals.
a medium-sized onion has only 44 calories but provides plenty of vitamins, minerals, and fiber (2).
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 the body, protecting cells from damage caused by unstable molecules called free radicals. （3）。
Onions are also rich in B vitamins, including folic acid (B9) and pyridoxine (B6), which play a key role in metabolism, erythropoiesis, and nerve function. （4）。
finally, they are a good source of potassium, a mineral that many people lack.
In fact, the average American potassium intake is just over half the recommended daily value (DV) of 4,700 milligrams (5).
potassium is required for normal cellular function, fluid balance, neurotransmission, renal function, and muscle contraction (6).
Summary: Onions are low in calories but rich in nutrients, including vitamin C, B vitamins, and potassium.
2. may be beneficial for heart health
onions contain antioxidants and compounds that fight inflammation, lower triglycerides, and lower cholesterol levels — all of which can reduce the risk of heart disease.
their powerful anti-inflammatory properties may also help lower high blood pressure and prevent blood clots.
quercetin is a flavonoid antioxidant that is highly concentrated in onions. since it is a potent anti-inflammatory agent, it may help reduce risk factors for heart disease, such as high blood pressure.
a study of 70 patients with overweight hypertension found that taking 162 mg of quercetin-rich onion extract daily resulted in a significant reduction in systolic blood pressure by 3-6 mm hg compared to placebo. （7）。
onions have also been shown to lower cholesterol levels.
A study of 54 women with polycystic ovary syndrome (PCOS) found that consuming large amounts of raw red onions (40-50 grams per day if overweight and 50-60 grams per day if obese) for eight consecutive weeks reduced total LDL and "bad" LDL cholesterol compared to control groups (8).
in addition, evidence from animal studies suggests that consuming onions may reduce risk factors for heart disease, including inflammation, high triglyceride levels, and thrombosis. （9, 10, 11）。
summary: research shows that eating onions may help reduce heart disease risk factors such as high blood pressure, elevated triglyceride levels, and inflammation.
3. rich in antioxidants
antioxidants are compounds that inhibit oxidation, and the oxidation process can cause cell damage and lead to diseases such as cancer, diabetes, and heart disease.
onions are an excellent source of antioxidants. in fact, they contain more than 25 different kinds of flavonoid antioxidants (12).
red onions, in particular, contain anthocyanins, a special plant pigment in the flavonoid family, that give red onions a dark color.
multiple population studies have found that people who consume more anthocyanin-rich foods have a lower risk of heart disease.
for example, a study of 43,880 men showed that daily intake of up to 613 mg of anthocyanins was associated with a 14% lower risk of a nonfatal heart attack. （13）。
similarly, a study of 93,600 women observed that women who consumed the most anthocyanin-rich foods were 32% less likely to develop heart disease than those who consumed the least amount. （14）。
in addition, anthocyanins have been found to prevent certain types of cancer and diabetes (15, 16).
summary: red onions are rich in anthocyanins, a powerful plant pigment that can prevent heart disease, certain cancers, and diabetes.
4. contains anti-cancer compounds
consumption of allium vegetables such as garlic and onions has been linked to a reduced risk of certain cancers, including stomach and colorectal cancer.
a review of 26 studies showed that people who consumed the most onions were 22% less likely to be diagnosed with stomach cancer than those who ate the least. （17）。
in addition, a review of 16 studies in 13,333 people showed that participants with the highest onion intake had a 15% lower risk of colorectal cancer compared to those with the lowest onion intake. （18）。
these anti-cancer properties are associated with sulfur compounds and flavonoid antioxidants found in allium vegetables.
For example, onions provide onion in A, a sulfur-containing compound that has been shown in test-tube studies to reduce tumor development and slow the spread of ovarian and lung cancer. （19, 20）。
onions also contain figuline and quercetin, flavonoid antioxidants that can inhibit tumor growth. （21, 22）。
summary: a diet rich in allium vegetables such as onions may have a protective effect against certain cancers.
5. helps control blood sugar
eating onions may help control blood sugar, which is especially important for people with diabetes or prediabetes.
in one study in 42 people with type 2 diabetes, consuming 3.5 ounces (100 g) of fresh red onions reduced fasting blood glucose levels by approximately 40 mg/dl after four hours (23).
in addition, multiple animal studies have shown that consuming onions may be beneficial in controlling blood sugar.
one study showed that diabetic rats who were fed food containing 5% onion extract for 28 days experienced a decrease in fasting blood sugar and significantly lower body fat than in the control group. （24）。
specific compounds found in onions, such as quercetin and sulfur compounds, have anti-diabetic effects.
for example, quercetin has been shown to interact with cells in the small intestine, pancreas, skeletal muscle, adipose tissue, and liver to control systemic blood sugar regulation. （25）。
summary: since many beneficial compounds are found in onions, consuming them may help lower high blood sugar.
6. can improve bone density
while dairy products have received a lot of praise for promoting bone health, many other foods, including onions, may help support strong bones.
a study of 24 middle-aged and postmenopausal women showed that those who consumed 3.4 ounces (100 ml) of onion juice daily for eight consecutive weeks had increased bone mineral density and antioxidant activity compared to the control group. （26）。
another study of 507 perimenopausal and postmenopausal women found that people who ate onions at least once a day had 5% higher overall bone density than those who ate them once a month or less. （27）。
in addition, the study showed that older women who ate onions most often had a more than 20% lower risk of hip fractures than women who never ate onions. （27）。
it is believed that onions help reduce oxidative stress, improve antioxidant levels and reduce bone loss, which may prevent osteoporosis and improve bone density. （28）。
summary: studies have shown that consuming onions is associated with improved bone mineral density.
7. has antibacterial properties
Onions can fight potentially dangerous bacteria such as E. coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus cereus (29).
in addition, onion extract has been shown to inhibit the growth of Vibrio cholera, a major public health problem in developing countries. （30）。
quercetin, extracted from onions, appears to be a particularly effective way to fight bacteria.
A test-tube study showed that quercetin extracted from the skin of a yellow onion successfully inhibited Helicobacter pylori (H. pylori). pylori) and methicillin-resistant growth of Staphylococcus aureus (MRSA). （31）。
H. pylori is a bacterium associated with stomach ulcers and certain digestive cancers, while MRSA is an antibiotic-resistant bacterium that causes infections in different parts of the body. （32, 33）。
another test-tube study found that quercetin damaged cell walls and cell membranes for e. coli and staphylococcus aureus (34).
summary: onions have been shown to inhibit the growth of potentially harmful bacteria such as e. coli and staphylococcus aureus.
8. may promote digestive health
onions are a rich source of fiber and prebiotics, which are necessary for optimal gut health.
prebiotics are indigestible fibers that are broken down by beneficial gut bacteria.
gut bacteria feed on prebiotics and produce short-chain fatty acids— including acetate, propionate, and butyrate.
studies have shown that these short-chain fatty acids can enhance intestinal health, boost immunity, reduce inflammation and promote digestion. （35, 36）。
in addition, eating prebiotic-rich foods helps increase probiotics, such as strains of lactobacillus acid bacteria and bifidobacterium, which are beneficial to digestive health. （37）。
a prebiotic-rich diet may help improve the absorption of important minerals such as calcium, thereby improving bone health (38).
onions are rich in prebiotic inulin and fructooligosaccharides. this helps increases the number of friendly bacteria in the gut and improve immune function (39).
summary: onions are a rich source of prebiotics that help promote digestive health, improve gut bacterial balance, and benefit the immune system.
9. easy to add to your diet
onions are a staple in kitchens around the world.
they add flavor to delicious dishes, either raw or cooked.
not to mention, they can increase your intake of fiber, vitamins, and minerals.
here are some tips on how to add onions to your diet:
- use raw onions to add flavor to your guacamole recipes.
- add caramel onions to delicious baked goods.
- combine the cooked onions with other vegetables to make a healthy side dish.
- try adding cooked onions to egg dishes, such as omelets, minced omelets, or quiches.
- serve with meat, chicken, or tofu, and sautéed onions.
- add thinly sliced red onions to your favorite salad.
- make a fiber-rich salad with chickpeas, chopped onions, and red peppers.
- use onions and garlic as a base for raw materials and soups.
- place the onion in the stir-fry.
- top tacos, page, and other Mexican dishes with chopped raw onions.
- make your own salsa with onions, tomatoes, and fresh parsley.
- prepare a hearty onion and vegetable soup.
- add onions to chili recipes to add flavor.
- raw onions are mixed with fresh herbs, vinegar, and olive oil for a delicious homemade salad dressing.
summary: onions can be easily added to savory dishes, including eggs, guacamole, meat dishes, soups, and baked goods.
long story short
the health benefits associated with onions are impressive.
these nutrient-rich vegetables contain powerful compounds that can reduce the risk of heart disease and certain cancers.
onions have antibacterial properties and promote digestive health, which may improve immune function.
what's more, they are versatile and can be used to enhance the flavor of any salty dish.
adding more onions to your diet is an easy way to benefit your overall health.