Onions are a real powerhouse. They reduce bad cholesterol, increase good cholesterol, help to reduce blood clotting, reduce risk of diabetes, kills bacteria, reduces risk of some cancers.
Onions have been used for centuries for healing wounds (used as a poultice) and sickness. We tried a slice on a fresh bruise and to my surprise, it really worked. It reduced the intensity of the bruise.
Onions also help with respiratory and sinus problems by opening airways. Onion has antiseptic qualities, it kills germs.
Yellow onions in particular contain a high amount of quercetin and other cancer fighting phytochemicals. The stronger the onion, the more powerful it is. But you might want to follow up with some parsley 😉