Updated: Mar. 17, 2022

Learn more about onion, one of the richest sources of chromium, and how it improves the body’s ability to respond to insulin.

Don’t cry for onions — embrace them! They may be synonymous with tears and onion breath, but they’re essential to cooks everywhere for their unique flavor. They’re also good for you. It’s true that these underground globes don’t offer a whole lot of nutrients, but what they have in bulk are powerful sulfur-containing compounds, which are responsible for their pungent odor — and many of their health benefits.

According to several studies, onions may help bring down high blood sugar in diabetic animals. In one Egyptian study of diabetic rats, onion juice reduced blood sugar levels by an amazing 70 percent. One of few published studies in humans, from India, dates back some 30 years, but it found that people with diabetes who ate 2 ounces (60 g) of onions a day experienced a significant drop in blood sugar levels. Researchers credit these effects to the sulfur compounds in onions as well as their flavonoids. These powerful antioxidant compounds also help fight some of the side effects of high blood sugar, not to mention heart disease.

Onions even seem to boost HDL, the “good” cholesterol. One study found that people who ate the most onions, along with other foods rich in flavonoids, had a 20 percent lower risk of heart disease. Thanks to their sulfur compounds, onions, like aspirin, also help prevent dangerous blood clots. And they’re known to help lower high blood pressure.

Finally, onions are one of the richest food sources of chromium, a trace mineral that improves the body’s ability to respond to insulin.

Health Bonus
Onions’ sulfur compounds and flavonoids may help fend off several forms of cancer. One Chinese study found that men who ate at least 1 tablespoon of chopped onions and other related vegetables (garlic, scallions, chives, and leeks) a day had about half the risk of developing prostate cancer compared to men who ate less than 1/4 tablespoon of these veggies daily. There’s also a link between a high intake of flavonoids and reduced risk of lung cancer.

Evidence suggests that onions may help preserve bone and prevent osteoporosis. And because the sulfur compounds are strongly anti-inflammatory, onions may also help relieve the pain and swelling of arthritis. The green tops of scallions, or spring onions, are rich in vitamin C and beta-carotene.

Glycemic Load: Very low

The more tears they cause, the more health benefits onions have. To stem the flood while you’re chopping, try chilling onions for about a half hour before cutting, and slice them from the top, leaving the root end intact; it has the strongest concentration of eye-burning compounds.

Be sure to wash onions well before chopping, especially if you’re going to eat them raw. Onions grow underground and can harbor nasty bacteria. Store onions in a cool, dry place, not in the fridge, and not near potatoes. Potatoes give off moisture and a gas that causes onions to spoil faster.

Antioxidant-Rich Onions
To reap the most benefit from onions, choose varieties with the most antioxidants. Here they’re ranked from highest to lowest (we’ve included shallots, which are related to onions). If you don’t recognize some of the names, don’t worry. Just know that sweeter or milder-tasting onions have fewer antioxidants than their more pungent counterparts.

  • Shallots
  • Western white
  • Western yellow
  • Imperial Valley sweet
  • Northern red
  • Vidalia

Menu Magic
Like garlic, onions can be added to just about anything. Here are just a few suggestions.

  • Add onions to almost any stew or stir-fry.
  • To get a bit of raw onion into your diet, combine chopped onions, tomatoes, avocado, and jalapeño peppers for a blood sugar–friendly chip dip. Finish with a splash of lime juice.
  • Sauté chopped onions in olive oil and add to corn, potatoes, or peas.
  • Add chopped scallions to rice dishes.
  • Add sliced onions to green salads.
  • Use chopped onions to add crunch to any sandwich salad, such as chicken, tuna, or egg salad.
  • Make fruit chutney with peaches, mangos, pears, apples, or apricots and plenty of chopped onion. Serve with meals as a condiment that won’t upset your blood sugar balance.
  • Roast some onions to serve as a savory side dish. Cut the root and top from a large onion. Place root side down on a foil-covered baking sheet and bake for about an hour at 400°F (200°C). When it’s done, remove it from the oven and make a deep crisscross cut in the top. Season with flavored vinegar, herbs, sea salt, coarse-ground pepper, and olive oil.
  • Enjoy French onion soup, but go easy on the bread and cheese topping. Try adding a few whole grain croutons instead.
  • Use caramelized onions to add wonderful flavor to any vegetable and pasta dish. To caramelize an onion, thinly slice onion, then heat 1 tablespoon olive oil in a heavy skillet over medium heat. Add onion and cook, covered, 10 minutes, stirring often. Remove cover and cook for 10 more minutes, stirring occasionally.

Perfect Portion: 1/4 cup
Onions have very few calories, so add them cooked or raw to as many dishes as you can think of. Minced raw onions offer the greatest health benefits.

Reader's Digest
Originally Published in Reader's Digest