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College of Food, Agricultural, and Environmental Sciences


Chow Line: Onions good for flavor, health (for 8/8/10)

July 30, 2010

We use onions when preparing supper almost every night. Do they add as much nutrition as they do flavor?

Onions are a perfectly good vegetable. They're not exactly a powerhouse of vitamins and minerals, but they do offer a respectable amount of fiber (almost 2 grams in a half-cup, chopped) and vitamin C, and small amounts of other vitamins and minerals.

But nutrition researchers also believe onions are a rich source of phytonutrients that appear to have heart benefits, assist with gastrointestinal health, and prevent some types of cancer. Researchers are particularly interested in quercetin, abundant in onions and also found in apple skins, tea and red wine, and how it may inhibit the ability of blood platelets to aggregate, thus preventing heart disease. Quercetin also appears to lower LDL cholesterol in the bloodstream while increasing beneficial HDL cholesterol. In addition, there's preliminary evidence that it may offer some protection against colon cancer, but more clinical trials are needed.

You're not alone in your love of onions. According to the National Onion Association, the average American eats about 20 pounds of onions per year, an increase from just over 12 pounds per person in 1983. Worldwide, the average is under 14 pounds of onions per person per year.

You may not know it from what's available at your grocery store, but there are more than 500 kinds of onions, usually categorized as either "fresh onions" or "storage onions."

Fresh onions are available from March through August. They have a thinner, lighter-colored skin and are typically sweeter, because of their higher water content, than storage onions. They also bruise more easily, so handle them with care.

Storage onions have several layers of thick, papery skin that's typically darker than what you see on fresh onions. They have a more intense flavor and less water.

According to the National Onion Association, both kinds of onions should be stored in a single layer in a cool, dry ventilated area; piling them up and insufficient air movement reduces their shelf life.

To reduce the risk of tears, the Onion Association suggests chilling onions for a half-hour before cutting into them. Then, cut off the stem end first, peeling the outer layers to the root end, which has the largest concentration of sulphuric compounds. When combined with water, those compounds produce a small amount of sulfuric acid, the tear-inducing culprit. If possible, keep the root end intact while cutting.

Chow Line is a service of Ohio State University Extension and the Ohio Agricultural Research and Development Center. Send questions to Chow Line, c/o Martha Filipic, 2021 Coffey Road, Columbus, OH, 43210-1044, or

Editor: This column was reviewed by Julie Kennel, registered dietitian and program specialist for Ohio State University Extension in the Department of Human Nutrition, in the College of Education and Human Ecology.

Martha Filipic
Julie Shertzer