An onion by any other name still may not smell sweet to most of us. Onions are notorious for causing malodorous breath and a trickle of tears. In both cases, sulfur-containing compounds are the culprits.
According to legend, Western cowboys referred to onions as “skunk eggs,” thanks to the sulfur compound’s ability to permeate the lungs. The sulfur is contained within a volatile oil that enters the lungs and then is exhaled with the breath.
Many a remedy has been recommended, including munching a mouthful of parsley, celery tops, coffee beans, cardamom seeds, roasted beetroots and cloves. None of these remedies appears to work every time for every mouth, so it’s best to invite your friends and relatives to share your onion with you.
Another endearing quality of onions is that ability to bring tears to just about any dry eye. A sulfur-containing chemical is also at work here, given off in pungent fumes as the onion bulb is cut. The precise chemical is so volatile that it has been difficult to study. The predominant view today is that the volatile sulfur compound combines with the moisture in your eye to form sulfuric acid, so it’s no wonder you want to cry.
You can avoid the sulfuric-acid irritation by chilling the onions first so that the chemical will be less volatile. Alternatively, the onion can be peeled under cold running water. The water will dissolve the fumes before they reach your eye.
The onion does have some truly redeeming qualities, lest you be left with the notion that the onion should be avoided. Onions have a number of sulfur-containing compounds that have medicinal properties, including fighting certain bacteria, such as Salmonella and E. coli. Recent studies indicate that onions may help lower the bad cholesterol (LDL) and increase good cholesterol (HDL). And more recent studies indicate that onions contain a flavonoid called quercetin, which is thought to provide some protection against cataracts, cardiovascular disease and cancer. Some studies have indicated that the more bitter, pungent onions have more flavonoid compound and, therefore, may be more healthful than mild types.
Whether mild or strong, onions are also a low-calorie source of vitamins C and B6, folate, potassium, and manganese and dietary fiber.