The idea that placing dishes of raw onions around the home would stave off illness dates back to the massive flu outbreak of 1919. The thinking went that halved onions could absorb germs. Even though that particular onion "fact" is merely a fiction, there are still plenty of good to recommend them: namely, great low-calorie flavor, plus a few legitimate health benefits to boot.
All about Alliums
You may think of onions as those white slices that come on your hamburger, but there's more to onions than you think. Onions are part of the Allium family, which includes a whole range of flavorful root vegetables: garlic; red, white and yellow onions; scallions (also called green or spring onions); shallots, leeks and chives. All alliums grow as underground bulbs with above-ground leaves and a flower stalk.