Turns out that onions are nothing to cry over — these flavorful bulbs are packed with nutrients. 

  • Onions are super-healthy,” 
  • They are excellent sources of vitamin C, sulphuric compounds, flavonoids and phytochemicals.”
  • Phytochemicals, or phytonutrients, are naturally occurring 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.

A particularly valuable flavonoid in onions is quercetin, which acts as an antioxidant that may be linked to preventing cancer. 

It also might have heart health benefits, though more studies need to be done,

Quercetin has a host of other benefits, as well, reducing the symptoms of bladder infections, promoting prostate health and lowering blood pressure.

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. 

Partly because of their use in cooking around the world, onions are among the most significant sources of antioxidants in the human diet. Their high levels of antioxidants give onions their distinctive sweetness and aroma.

  • Foods that are high in antioxidants and amino acids allow your body to function optimally,”. “Antioxidants help prevent damage, and cancer. 
  • Amino acids are the basic building block for protein, and 
  • Protein is used in virtually every vital function in the body.
  • Sulfides in onions contain necessary amino acids. Sulfur is one of the most common minerals in our body that assists with protein synthesis and building of cell structures. 
  • Onions are low in calories (45 per serving), very low in sodium, and contain no fat or cholesterol. 
  • Onions  contain fiber and folic acid, a B vitamin that helps the body make healthy new cells. 

Onions are healthy whether they’re raw or cooked, though raw onions have higher levels of organic sulfur compounds that provide many benefits. There is a high concentration of flavonoids in the outer layers of onion flesh, so you’ll want to be careful to remove as little of the edible part of the onion as possible when peeling it.

Nutrition facts

1 medium onion 

  • 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%)

Health Benefits 

  1. Heart health Onions encourage a healthy heart in many ways, including “lowering blood pressure and lowering heart attack risk.” Sulfur acts as a natural blood thinner and prevents blood platelets from aggregating. When platelets cluster, the risk for heart attack or stroke increases. 
  2. Consuming  onions increases oxylipins that help regulate blood fat levels and levels of cholesterol.
  3. The quercetin in onions may also help prevent plaque buildup in the arteries, which reduces the risk of heart attack and stroke. 


  1. Onions’ sulfurs may be effective anti-inflammatory agents. 
  2. Quercetin has been found to relax the airway muscles and may provide relief of asthma symptoms. 

Immune system

  • The polyphenols in onions act as antioxidants, protecting the body against free radicals. 
  • Eliminating free radicals can help encourage a strong immune system. 
  • Quercetin  in onions also reduces allergic reactions by stopping your body from producing histamines, which are what make you sneeze, cry and itch if you’re having an allergic reaction.


  • Intake  of allium vegetables, including onions, were associated with reduced gastric cancer risk. 
  • Eating  between one and seven servings of onions per week may help reduce the risk of colorectal, laryngeal and ovarian cancer. Eating several servings of onions a day may help decrease the risk of oral and esophageal cancer.

Quercetin may be a powerful anti-cancer agent. Quercetin  may especially inhibit cancer cells in “breast, colon, prostate, ovarian, endometrial, and lung tumors.

People  who ate onions absorbed twice as much quercetin as those who drank tea, and more than three times as much quercetin as those who ate apples, which are other high-quercetin sources. Red onions are especially high in quercetin, according to the association. Shallots and yellow onions are also good options. White onions contain the least amount of quercetin and other antioxidants.
Onions may help with some side effects from cancer treatments, as well. 

Consuming  fresh yellow onion help lessen insulin resistance and hyperglycemia in breast cancer patients undergoing a form of chemotherapy known to cause insulin resistance.


The fiber in onions promotes good digestion and helps keep you regular. Additionally, onions contain a special type of soluble fiber called oligofructose, which promotes good bacteria growth in your intestines. 

Oligofructose  may help prevent and treat types of diarrhea. The phytochemicals in onions that scavenge free radicals may also reduce your risk of developing gastric ulcers. 

Regulating blood sugar

The chromium in onions assists in regulating blood sugar. The sulfur in onions helps lower blood sugar by triggering increased insulin production. This might be especially helpful to people with people with diabetes. People with Type 1 and Type 2 diabetes who ate red onions showed lower glucose levels for up to four hours.  
Patients with Type 2 diabetes saw more normalized liver enzymes and lower glycemic levels when consuming sliced onions.

Bone density in older women

Daily consumption of onions improves bone density in women who are going through or have finished menopause. Women who ate onions frequently had a 20 percent lower risk of hip fracture than those who never ate onions.

Health risks

While not especially serious, eating onions can cause problems for some people. The carbohydrates in onions may cause gas and bloating. 

Onions, especially if consumed raw, can worsen heartburn in people who suffer from chronic heartburn or gastric reflux disease. 

Eating a large amount of green onions or rapidly increasing your consumption of green onions may interfere with blood thinning drugs. 

Green onions contain a high amount of vitamin K, which can decrease blood thinner functioning.
It is also possible to have a food intolerance or an allergy to onions, but cases are rare. People with onion allergies may experience red, itchy eyes and rashes if an onion comes into contact with the skin. People with an intolerance to onions may experience nausea, vomiting and other gastric discomfort.

Onions keep for a long time, but they still spoil. Onions spoil much faster if they are chopped or sliced. If you cut up your onions for later use, be sure to refrigerate them in a closed container. 

Onion facts

Slicing onions makes you cry because when you cut into it, the onion produces a sulfur-based gas. The gas reacts with the water in your eyes and forms sulfuric acid. To rid your eyes of this fiery irritant, your tear ducts work overtime. For no more (or fewer) tears, try moving your face farther away from the onion so the gas disperses before reaching your eyes.
Another suggestion for reducing tears is to first chill the onions for 30 minutes. Then, cut off the top and peel the outer layers leaving the root end intact.
Bulb onions are yellow, red or white.

Onions range in size from less than 1 inch to more than 4.5 inches in diameter. 
Scallions, or green onions, are actually immature yellow, red or white onions, harvested before the bulb begins to form. “Spring onions” and “salad onions” are other aliases for immature onions.
A scallion is not a shallot. This misnomer probably occurs because “échalion” is another name for the shallot, derived from the French échalote. Shallots have a distinctive taste, but the flavor is closer to that of mature onions than to that of scallions.
The largest onion ever grown weighed 10 lbs. 14 ounces (about 5 kilograms), according to the Guinness Book of World Records.
The leading onion production countries are China, India, United States, Turkey and Pakistan.
To avoid “onion breath,” eat a sprig of parsley, or rinse your mouth with equal parts lemon juice and water, or chew a citrus peel.


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