Health Benefits of Red Onion

The Egyptians buried onions with their pharaohs. The Greeks prepared for the Olympics by feasting on onions. The Pilgrims even brought onions with them to America. Today onions appear in cuisines all around the world. Onions belong to the allium family, along with garlic, leeks, shallots, and scallions. 

Red onions were originally cultivated in three different places: Turda, Romania; Tropea, Italy; and Wethersfield, Connecticut, in the United States. Sometimes called purple onions, they add color and flavor to many dishes.  

Health Benefits

Scientists have linked onions with many health benefits. Most of the benefits come from antioxidants. Research shows that one particular antioxidant, called quercetin, protects health in several ways. One study shows that quercetin fights inflammation and boosts the immune system.

Onions have other health benefits such as:

Antibacterial Action

Research mainly conducted in labs has shown that onions may kill a wide range of bacteria. In one experiment, onion and garlic extracts inhibited the growth of several microbes. Garlic extract also reduced bacteria in the mouths of human volunteers. More research with human subjects is needed to show how onion affects bacteria in the body.

Cancer Risk Reduction

Eating onions and garlic may reduce your risk of cancer. Italian researchers found that those who ate the most onions were the least likely to have cancer of the colon, throat, and ovaries. In another study, researchers found that men who ate the most vegetables of the allium family were the least likely to have prostate cancer. Researchers believe that antioxidants are responsible for the cancer-fighting properties of onions.

Digestive Health

Onions contain fructooligosaccharides, substances that act as prebiotics. They pass through the small intestine without digesting. In the large intestine, they feed the healthy bacteria. Diseases ranging from diabetes to colon cancer and depression have been tied to a lack of healthy gut bacteria

Bone Health

Onions may play a role in preventing osteoporosis. Both animal and human studies have supported this idea. In one study, researchers surveyed women near or past menopause about their onion intake. After the researchers controlled for other factors, they found the women who ate onions daily had greater bone density. This result is encouraging because older women are most at risk of osteoporosis.

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Nutrition

Besides being rich in antioxidants, onions contain a fair amount of:

Nutrients per Serving

The basic nutritional profile is almost exactly the same for white, yellow, and red onions. A half-cup serving of chopped red onion contains:

  • Calories: 32
  • Protein: 1 gram
  • Fat: 0 grams
  • Carbohydrates: 7 grams
  • Fiber: 1 gram
  • Sugar: 3 grams

Onions and Food Safety

Health authorities in the United States traced a 2020 outbreak of salmonella to onions grown in Bakersfield, California. The outbreak was unusual because onions are resistant to most bacteria. Their papery outer skin is a barrier to contamination, and the drying process that prepares them for the market further reduces the chances of bacterial growth. 

Some believe that a cut onion will attract and absorb bacteria, but no proof has ever been given to support this claim. People have circulated this myth via email and social media since 2008. Onions have antimicrobial properties, so they are one of the least likely vegetables to harbor bacteria. Still, you should store cut onions in the refrigerator.

How to Prepare Red Onion

Many recipes using onion call for chopped or sliced onion. Knowing the best way to cut an onion can help.

Once you have your onions chopped or sliced, try one of these recipes:

  • Make your own pickled red onion to jazz up almost any meal.
  • Add red onion to make a tomato and cucumber salad look and taste lovely. 
  • Throw red onion and green pepper on the grill with skirt steak for beef fajitas. 
  • Add sliced red onion to your beef or veggie burger.
  • Toss chunks of red onion and other vegetables with a little olive oil and oven roast.
  • Add red onions to the classic combo of green beans and new potatoes.
  • Sub red onions for the green ones in tabbouleh
WebMD Medical Reference Reviewed by Dan Brennan, MD on September 18, 2020

Sources

SOURCES:

Die Pharmazie: "The antimicrobial activity of garlic and onion extracts."

ESHA Research, Inc., Salem, Oregon.

Journal of the National Cancer Institute: "Allium Vegetables and Risk of Prostate Cancer: A Population-Based Study."

Journal of Physiology and Biochemistry: "Dietary fructooligosaccharides and potential benefits on health."

Menopause: "The association between onion consumption and bone density in perimenopausal and postmenopausal non-Hispanic white women 50 years and older."

National Onion Association: "Common Myths."

National Onion Association: "Onion History."

National Onion Association: "Red Onions and Salmonella."

Nutrients: "Quercetin, Inflammation, and Immunity."

Vegetable Facts: "Red Onion — Benefits and Healthy Facts About Red Onions."

© 2020 WebMD, LLC. All rights reserved.

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