Onions are a good source of vitamin C, although they lose some of their vitamin C content when they are factory-processed by freezing or canning and also when they are cooked. You'll probably get the most vitamin C from onions if you enjoy them in their least-processed states, such as chopped and raw in a taco salad, or fresh and lightly steamed with other veggies.

Vitamin C Amounts in Onions

Per USDA figures, 1/2 cup of canned onions contains 4.8 mg vitamin C, whereas about 1/2 cup, or 100 g, of frozen, chopped onions contains 3.3 mg of vitamin C. High-heat cooking, such as sautéing, seems to produce the greatest vitamin C losses, 1/2 cup of sautéed onions has only 0.8 mg vitamin C.

Vitamin C in Onion Food Products

Do Onions Have Vitamin K?

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Some food products containing onions, such as:

  • onion soup or onion rings
  • also provide some vitamin C

According to the USDA
a 1 cup serving of canned
prepared onion soup offers 1.2 mg of vitamin C
whereas 10 medium-sized onion rings contain 0.8 mg of vitamin C. However
as the soup is high in sodium
the onion rings contain a lot of saturated fat
eating these foods probably isn't the healthiest way to get more vitamin C in your diet. Even worse are onion-flavored potato chips which contain, per gram, more salt than canned onion soup and more fat than onion rings. Onion potato chips also have 1.2 mg of vitamin C, but again, salty, fatty foods aren't the most nutritious ways to eat onions.

Other Nutrients in Onions

Additionaly, according to Lexington, Kentucky news website, Kentucky.com, onions contain more the micronutrient quercitin than any other common fruit or vegetable. According to Dole Nutrition Institute nutrition researcher, Nicholas D. Gillitt, quercitin is a potent antioxidant that has been linked to a reduced risk of developing heart disease and certain types of cancers.

Other Foods With Vitamin C

The Effects of Onions on Cholesterol & Blood Sugar

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If onions really aren't your thing, there are still plenty of other healthy foods that provide vitamin C. The best dietary sources of vitamin C include: citrus fruits and their juices, red and green peppers, and kiwifruit.