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Health
Some love them, others hate them, but onions undeniably have numerous health benefits. And there are many ways to incorporate them into your favorite dishes and supplements.
Onions are highly nutritious vegetables with many benefits, members of the Allium genus of flowering plants, which also includes garlic, shallots and leeks.
Relatively inexpensive, they have a wide range of vitamins, minerals and healthy plant compounds. The medicinal properties of onions have been recognized for thousands of years.
Athletes in Ancient Greece used onions to purify the blood, while medieval doctors prescribed them to treat headaches, heart disease and mouth sores. (1).
Their composition
Onions are highly nutritious, which means they are low in calories but rich in vitamins, fiber and minerals.
One medium onion (110 grams) contains:
Calories: 44
Protein: 1.2 g
Carbohydrates: 10.3 g
Sugar: 4.7 g
Fiber: 1.9 g
Fat: 0.1 g
Vitamin C
Onions have vitamin C, which can help regulate your immune health, collagen production and iron absorption.
It's also a powerful antioxidant that can help protect your cells from unstable and harmful molecules called free radicals. (2)
B complex
Onions are rich in B vitamins, including folate and vitamin B6. These play key roles in metabolism, red blood cell production and nerve function. (3)
Potassium
Finally, onions are a good source of potassium, a mineral that can help with:
cellular function
fluid balance
nerve transmission
kidney function
muscle contraction
Adding onions to your diet is a great way to increase your potassium intake. (4)
Health benefits
Boosts immunity
Vitamin C helps to boost the body's immunity by helping to generate white blood cells that defend the body against bacteria and viruses, making raw onions an ally in preventing common illnesses such as colds and flu.
Skin care
Raw onion contains high levels of antioxidants and vitamin C, which contribute to improving skin health, helping to reduce wrinkles, age spots and pigmentation levels, providing healthy, glowing skin.
Heart health
Onions contain antioxidants and compounds that can reduce the risk of heart disease by fighting inflammation and lowering triglyceride and cholesterol levels.
It contains a high amount of quercetin, a flavonoid antioxidant and anti-inflammatory that can help reduce high blood pressure(5)
A small 2015 study of overweight and hypertensive people who took a daily dose of 162 mg of onion extract showed a significant reduction in systolic blood pressure of 3.6 millimeters of mercury.
In addition, a small 2014, study in obese women found that consuming 80-120g of raw red onions a day for 8 weeks reduced total and LDL (bad) cholesterol levels.
However, more studies are needed.
Source of Antioxidants
Oxidation is a process that can lead to cell 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 from the flavonoid family that give red onions their deep color. These can protect against diabetes and certain types of cancer(6).
In a 2016 study of 43,880 men, researchers found that habitual anthocyanin intake of up to 613 mg was correlated with a 14% lower risk of non-fatal heart attacks.
A 2019 review also concluded that consuming more foods rich in anthocyanins was associated with a lower risk of heart disease and death from heart disease.
Anti-cancer action
Onions reduce the risk of developing certain types of cancer, including stomach and colorectal cancers.
A 2015 review concluded that people who consumed more allium vegetables were 22% less likely to be diagnosed with stomach cancer than those who consumed less.
A 2014 review concluded that people with the highest onion consumption had a 15% lower risk of colorectal cancer than those with the lowest consumption.
Test-tube studies suggest that cebolin A, a sulfur-containing compound in onions, may help decrease the development of tumors and slow the spread of ovarian cancer (7, 8).
Fisetin (another compound in onions) and quercetin, which are flavonoid antioxidants that can inhibit tumor growth. (9 10)
Regulates blood sugar
Helping to regulate blood sugar levels is important for people with diabetes or pre-diabetes.
A small 2010 study of type 1 or type 2 diabetics 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 lower fasting blood sugar levels and lower triglyceride and cholesterol levels.
Quercetin has also been shown to help regulate blood sugar balance throughout the body by interacting with cells in the: small intestine, pancreas, skeletal muscle adipose tissue, liver. (11)
May increase bone density
A small study of 2016 middle-aged women found that those who consumed 100 milliliters of onion juice daily for 8 weeks had improved bone mineral density and antioxidant activity.
Another 2009 study showed that those who ate onions at least once a day had an overall bone density 5% higher than those who ate onions once a month or less frequently.
The explanation is that onions can help reduce oxidative stress, increase antioxidant levels and decrease bone loss. This can help prevent osteoporosis and improve bone density.
Antibacterial
Onions can help fight potentially dangerous bacteria such as:
Escherichia coli (E. coli)
Pseudomonas aeruginosa
Staphylococcus aureus (S. aureus)
Bacillus cereus
A 2010 test tube study showed that onion extract can inhibit the growth of Vibrio cholerae, a type of bacteria that is a major public health concern in some parts of the world.
A 2022 article concludes that flavonoid-rich plant extracts with anti-H. pylori potential have shown themselves to be a promising alternative therapeutic source. Helicobacter pylori (H pylori) is a type of bacteria associated with stomach ulcers and certain digestive cancers.
Quercetin extracted from onions can also reduce the growth of bacteria.
Another test tube study found that quercetin damaged the cell walls and membranes of E. coli and S. aureus (12)
Reduces inflammation
Quercetin also has anti-inflammatory properties that help reduce inflammation levels in the body. It helps control diseases such as arthritis, asthma and bronchitis.
Can improve digestive health
Onions are rich in non-digestible types of fiber broken down by beneficial intestinal bacteria.
The gut bacteria feed on probiotics and create short-chain fatty acids, which help to:
strengthen intestinal health
boost immunity
reduce inflammation
improve digestion
Eating probiotic foods can also help increase probiotics, such as Lactobacillus and Bifidobacterium strains, the gut bacteria that benefit digestive health.
Onions are rich in the probiotics inulin and fructooligosaccharides, which can help increase the number of friendly bacteria in your gut and improve immune function.
Increases brain function
Raw onions contain sulfur compounds, which increase the production of neurotransmitters in the brain, leading to improved memory, attention span and concentration levels.
Source of sulfur
Your body needs sulfur to build and repair your DNA and protect your cells from damage that can lead to serious illnesses. Sulfur also helps the body metabolize food and contributes to healthy skin, tendons and ligaments. Lack of sulfur can lead to problems such as depression, bad smelling saliva, loss of skin viscosity, among others. (webmed)
Onions ( Allium cepa L.) contain phenolic compounds and sulfur-containing compounds such as thiosulfinates and thiosulphonates( 1 ). These sulfur compounds can also block the formation of platelet clots and promote the breakdown of blood clots, which helps to lower the risk of heart disease and strokes
Onions form sulfur compounds through an enzymatic reaction when cut or crushed.
Raw onions have the highest sulfur content, as cooking them significantly reduces the amount of the compound.
How to consume
All types of onion are good, but the dark reddish-purple variety, sometimes called red onion, has especially high levels of quercetin and other useful plant compounds known as flavonoids. Flavonoids give colors to many fruits, vegetables and flowers.
You should eat onions raw, rather than cooked, to get the most sulfur compounds from them.
Red onions have a mild, sweet taste and add color and flavor to many dishes. Use them as a crunchy addition to salads, sandwiches and sauces.
If you don't like onion pieces, try blending them with chickpea paste (hummus), herbs and olive oil to make a delicious salad dressing
Another option is to use the same recipe above as a spread to eat with bread and sandwiches, or simply as a purée to accompany meat.
If you want a low-carb version, use hard-boiled eggs beaten with onion for a multipurpose cream.
Attention
Disadvantages of eating raw onions
Gas and bloating. The same substances present in onions that feed the healthy bacteria in the gut can be difficult for some people to tolerate. If onions bother you, avoid them or limit them, especially when they are raw.
Changes in body odor. When your body breaks down the sulfur compounds found in onions, they can react with the sweat on your skin, creating what is generally considered to be an unpleasant body odor. And, of course, they can also cause bad breath.
Food poisoning. To reduce the risks, avoid eating onions that are bruised or have broken skins, and sanitize them before use.
Disclaimer: this content, including advice, provides generic information only. It in no way replaces a medical opinion.