Onions: Overview, Nutritional Profile, Types, Uses, Health Benefits, Side Effects, Risks, and Other


Onions are very healthy vegetables that can help with heart health, blood sugar control, and stronger bones. Onions belong to the Allium family which also includes garlic, shallots, and leeks. They taste good, can be used in many ways, are not expensive and have lots of healthy vitamins, minerals, and plant chemicals. People have known about the healing properties of onions for thousands of years. Athletes in ancient Greece used onions to clean their blood, and doctors in medical times used them to treat headaches, heart disease, and mouth sores. For more research you can also visit Wikipedia.

What are the Onions?

Onions (Allium cepa) are plants grown all over the world. People often eat the onion bulb as food. Onion bulbs and extracts are also used to make medicine. Onions have chemicals that can help reduce swelling and make it easier to breathe for people with asthma. They also have chemicals that can lower cholesterol and blood sugar. Some people use onions to prevent scars. They are also used for weight loss, hair loss, asthma, trouble sleeping, high blood pressure, warts, and many other problems, but there is not strong scientific proof that onions help with these uses.

What is the Nutritional Profile of Onions?

Onions are very healthy because they have lots of vitamins, minerals, and antioxidants, but not many calories. One cup of chopped onions has:

  • Calorie: 64
  • Carbohydrates: 14.9 grams
  • Fat: 0.16 grams
  • Cholesterol: 0 gram
  • Fiber: 2.72 gram
  • Sugar: 6.78 grams
  • Protein: 17.6 grams

According to the Dietary Guidelines for Americans, onions are a good source of many important nutrients.

  • Nutrients: Vitamins C(RDA), Vitamin B-6 (RDA), and manganese (AI),
  • Percentage of Daily Requirement in Adults: 13.11% for males and 15.73% for females, 11.29-14.77% depending on age, 8.96% for males and 11.44% for females.

Onions also contain small amount of:

  • Calcium
  • Iron
  • Folate
  • Magnesium
  • Phosphorus
  • Potassium
  • Antioxidants

What are the Types of Onions?

Here are some types of onions. Such as:

  • Yellow onions
  • Sweet onions
  • White onions
  • Red onions
  • Shallots
  • Green onions
  • Leeks

What are the Uses of Onions?

Possibly Effective for:

Scarring: Using a gel with onion extract on the skin for at least 10 weeks can help scars look better. However, it’s not clear which mix of ingredients or how much works best.

Possibly Ineffective for:

Obesity: Eating onions or taking onions extract does not help people lose weight if they are overweight or obese. People are interested in using onions for many other things, but there isn’t enough reliable information to know if they work.  

What are the Health Benefits of Onions?

May Benefit Heart Health:

Onions have antioxidants and compounds that might lower your risk of heart disease by reducing inflammation and lowering triglycerides and cholesterol levels. They have a lot of quercetin, an antioxidant and anti-inflammatory, that may help lower high blood pressure. A small study in 2015 with overweight people who had high blood pressure found that taking 162 mg of quercetin-rich onion extract daily reduced systolic blood pressure by 3.6 mm Hg. Also a small study in 2014 with 54 women with polycystic ovary syndrome found that eating 80-120 grams of raw red onions per day for 8 weeks lowered total and LDL (bad) cholesterol levels.

Load with Antioxidants:

Antioxidants are compounds that stop oxidation, which can damage cells and lead to diseases like cancer, diabetes, and heart disease. Onions are a great source of antioxidants and have at least 17 types of flavonoids. Red onions have anthocyanins, which are pigments in the flavonoids family that give red onions their deep color. These may help protect against diabetes and certain cancers. A 2016 study with 43,880 men found that regularly consuming up to 613 mg of anthocyanins was linked to a 14% lower risk of nonfatal heart attacks. A 2019 review also concluded that eating more anthocyanins-rich foods was associated with a lower risk of heart disease and death from heart disease.

Contain Anticancer Compounds:

Allium vegetables like onions and garlic might lower the risk of certain cancers, including stomach and colorectal cancer. A 2015 review of 26 studies found that people who ate the most allium vegetables were 22% less likely to get stomach cancer compared to those who ate the least. A 2014 review of 16 studies with 13,333 people found that those who ate the most onions had a 15% lower risk of colorectal cancer than those who ate least. Lab studies suggest that onions A, a sulfur compound in onions, might help reduce tumor growth and slow the spread of ovarian cancer. Onions also have fisetin and quercetin, which are antioxidants that might help stop tumors from growing.

Help Regulate Blood Sugar:

Eating onions may help control blood sugar levels, which is important for people with diabetes for prediabetes. A small 2010 study with 84 people who have type 1 and type 2 diabetes found that eating 100 grams of raw red onions significantly reduced fasting blood sugar levels after 4 hours. A 2020 study showed that diabetic rats that ate food with 5% dried onion powder for 8 weeks had lower fasting blood sugar, triglycerides, and cholesterol levels compared to a control group. Quercetin, found in onions, also helps control blood sugar by interacting with cells in the small intestine, pancreas, skeletal muscles, fat tissues, and liver.

May Boost Bones Density:

While dairy is known for promoting bone health, other foods like onions may also support strong bones. A small study in 2016 with middle-aged and postmenopausal women found that those who drank 100 ml of onion juice daily for 8 weeks had better bone mineral density and antioxidant activity compared to a group that didn’t. Another study in 2009 with 507 women going through menopause found that those who ate onions daily had 5% higher overall bone density than those who ate onions less than once a month. Onions can reduce oxidative stress, increase antioxidants, and lower bone loss, which might help prevent osteoporosis and improve bone density.

Have Antibacterial Properties:

Onions can help fight harmful bacteria such as:

  • Escherichia coli (E. coli)
  • Pseudomonas aeruginosa
  • Staphylococcus aureus (S. aureus)
  • Bacillus cereus

A study in 2010 using test tubes suggests that onion extract might help stop Vibrio cholerae, a bacterium that’s a big health problem in some places. Quercetin from onions can also reduce bacteria growth. One review says it might stop several types of bacteria including Helicobacter pylori, which can cause stomach ulcers and some digestive cancers. Another test-tubes found that quercetin hurt the cell walls and membranes of E. coli and S. aureus.

May Boost Digestive Health:

Onions have lots of fiber and prebiotics, which are important for a healthy gut. Prebiotics are kinds of fiber that can’t be digested but are broken down by good bacteria in your gut. These bacteria ear prebiotics and make short-chain fatty acids, which might:

  • Make your gut healthier
  • Boost your immune system
  • Lower inflammation
  • Improve digestion

Eating prebiotic foods can also increase probiotics like Lactobacillus and Bifidobacterium, which help your digestive system. Onions contain inulin and fructooligosaccharides, types of prebiotics that can increase friendly bacteria in your gut and improve your immune system.

Easy to Add to Your Diet:

Onions are a fresh and versatile staple in kitchens around the world. They can also be cooked, fried, eaten raw, and more. To incorporate onions into your diet, you can try:

  • In soups like French onions soup.
  • In dips and spreads such as guacamole, salsa, and ranch.
  • In egg dishes like omelets, frittatas, and quiches.
  • Cooked as toppings like caramelized onions for meat, tofu, or savory baked goods.
  • Raw as topping for tacos, fajitas, and other Mexican dishes, as well as savory baked goods.
  • In salads, such as a chickpea salad with chopped onions and red peppers.
  • In stir-fries, pasta sauces, or curries.

What are the Side Effects of Onions?

Here are some side effects of onions. Such as:

  • May aggravate IBS symptoms
  • Some people may be allergic
  • May irritate the eyes
  • May cause heartburn
  • Bad breath
  • Drug interaction

What are the Risks of Onions?

Onions are considered safe for the majority of people who consume them. However, it’s worth noting that some individuals may have allergies or intolerances to onions. If someone experiences adverse reactions such as digestive discomfort, skin rash, or respiratory symptoms after eating onions, it’s crucial to seek medical attention promptly. Allergic reactions to onions can vary in severity so it’s important for individuals with known allergies or those experiencing symptoms for the first time to consult a healthcare professional for proper diagnosis and management.

What are the Precautions of Onions?

Here are some precautions of onions. Such as:

  • Pregnancy and Breastfeeding: There isn’t enough reliable information about the safety of using onion as a medicine during pregnancy or while breastfeeding. It’s best to avoid using onion in large amounts beyond normal food consumption.
  • Bleeding Disorder: Onions can slow down blood clotting. Using onion or onion extract as a medicine might increase the risk of bleeding if you have a bleeding disorder. Avoid using medicinal amounts of onion.
  • Diabetes: Onions may lower blood sugar levels. If you have diabetes and are using onion as a medicine, monitor your blood sugar closely.
  • Surgery: It may affect blood clotting and blood sugar levels. To avoid potential complications, stop using onion as a medicine at least two weeks before any scheduled surgery.

What You Need to Know About Food Allergies?

In people with a food allergy the immune system reacts to specific proteins in food as if they were harmful invaders. There are many types of food allergies, but some foods are more commonly allergenic than others. The National Institutes of Allergy and Infectious Diseases estimates that food allergy affects about 4% of adults and 5% of children in the United States. Reported cases of food allergies have been on the rise. For example, peanut allergies among children in North America have doubled over the past decade. Most food allergies start in children and many children outgrow them, although this isn’t always the case. Food allergies can also develop in adults but this is less common.

What are the Causes of Food Allergies?

In individuals with food allergies, the immune system identifies a specific protein in food as harmful and potentially disease causing. It responds by producing lgE antibodies which are designed to combat this protein. Upon subsequent consumption of the same food, these antibodies are primed and ready. The immune system swiftly reacts by releasing histamine and other chemicals into the bloodstream. These substances trigger the symptoms of food allergies. Histamine causes blood vessels to widen leading to inflammation and swelling of the skin. It also affects nerve endings causing itchiness. Increased mucus production in the nose can result in itching, burning sensations, and a runny nose.     

What are the Symptoms of Food Allergy?

Symptoms of food allergies can vary from mild to severe and affect each person differently. Not everyone will experience all possible symptoms, and each reaction can be a bit different. Common signs and symptoms include:

  • Tingling in the mouth
  • Burning sensation in the lips and mouth
  • Swelling on the face
  • Skin rash known as hives
  • Wheezing
  • Nausea and vomiting
  • Diarrhea
  • Runny nose
  • Watery eyes

Symptoms of Anaphylaxis:

Anaphylaxis is a severe, widespread allergic reaction. It usually happens soon after exposure to the allergen but can sometimes take a few hours to develop. The signs and symptoms of food allergies usually appear quickly and worsen rapidly. They may include:

  • A sudden drop in blood pressure
  • Fear or anxiety
  • An itchy or tickly throat
  • Nausea
  • Breathing problem, such as wheezing or shortness of breath, which often get worse
  • Itchy skin or rash throat that spreads quickly over much of the body
  • Sneezing
  • Runny nose
  • Watery eyes
  • Rapid swelling of the throat, lips, face, and mouth
  • Vomiting
  • Loss of consciousness

Common Food Allergy Triggers:

The most common allergenic foods account for about 90% of all food allergies. People often call them the big eight allergens. These foods are:

According to the American College of Allergy, Asthma & Immunology, the most common food allergens for children are milk, eggs, and peanuts.

What is the Diagnosis of Food Allergy?

To diagnose an allergy, the doctor will ask the person about their reactions to certain foods. They will want to know:

  • What symptoms occur
  • How long it takes for the reaction to start
  • Which foods cause the reaction
  • Whether the food is cooked or raw
  • Whether the person eats the food

The doctor will also ask about any other existing allergies, such as seasonal allergies or asthma, and the person’s family history of allergies. The following tests can help the doctor diagnose a food allergy:

  • Skin prick test
  • Blood test
  • Food diary
  • Physician-supervised blinded oral food challenge

What is the Treatment of Food Allergy?

The traditional way to manage food allergies is to avoid the food that causes the reaction. People can also treat symptoms when they appear. Oral immunotherapy is a newer approach to managing food allergies. It involves giving a person increasing amounts of the allergen to raise the threshold that triggers a reaction. Oral immunotherapy is not available for all food, but the Foods and Drug Administration (FDA) has approved a treatment for peanut allergy called Palforzia. Accordingly, the allergen might involve not eating, inhaling, or touching the food, as well as avoiding foods with traces of it. Utensils, dishes, cooking surfaces, and cutting boards may also need to be free of the allergen. When on an elimination diet, a person may need to find other sources of certain nutrients. For example, since milk is a common source of calcium and protein, those avoiding it will need to get these nutrients from other foods. People will need to read food and drink labels carefully. Even some soaps, pet foods, glues, and adhesives might contain traces of a food allergen.

Medications for Emergencies:

The following medications are helpful during an allergic reaction:

  • Antihistamine: These come as gels, liquids, or tablets. They are usually effective for people with mild or moderate food allergy symptoms. Histamine causes most allergy symptoms, and antihistamine blocks their effects.
  • Epinephrine (adrenaline): This is for individuals who may have anaphylaxis due to food allergies. Epinephrine keeps blood pressure up by narrowing blood vessels and relaxes the airways. People who have had severe allergic reactions should always carry an epinephrine auto-injector, such as an EpiPen, EpiPen Jr., Twinject, or Auvi-Q.


Is it good to eat onions every day?

Eating onions daily can be good for you because they are rich in nutrients and have many health benefits. However, they may cause digestive discomfort for some people, especially those with digestive problems.

Do onions increase testosterone?

Onions are praised as aphrodisiacs, which are foods that boost sexual desire. They have been shown to increase testosterone production in males. Older studies also indicate that fresh onion juice increases testosterone levels and ejaculation in male.

Is onion a blood thinner?

Research at the University of Wisconsin has found that onions produce an anticoagulant that thins the blood more effectively than aspirin. The downside is that this blood-thinning effect is stronger in pungent onions, which can cause heartburn.

Why not eat onions at night?

If you’ve ever experienced heartburn or reflux, you might want to skip raw onions at your next late-night summer BBQ. Not only will your partner appreciate it when you go in for a bedtime kiss, but your body will thank you too. Onions are known to cause gas, reflux, and bloating all of which can interfere with your sleep.

Are onions good during periods?

Based on the study’s finding, the use of onion juice can be highly effective in alleviating this pain and can be recommended as an effective treatment. Besides hypomenorrhea, other menstrual disorders also showed a positive response to onion consumption.

Can onions remove belly fat?

Onions are rich in soluble fiber, making them a potent prebiotic food that promotes a healthy gut. This is crucial for weight loss, and reducing belly fat. Whether baked, juiced added to soups, or eaten raw, there are numerous ways to incorporate onions into your diet to help you lose fat quickly.

Are onions good in summer?

Onions possess natural cooling properties, making them a beneficial addition to summer diets.

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Probiotics: Definition, Types, Health Benefits, Side Effects, Risks, and Other

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