Onions are an excellent natural source of quercetin, one of the best nutrients for people whose goal is to have a wrinkle-free skin. But the contribution of onions to youthful skin does not stop there. The vitamin C and sulphur that onions provide protect the skin and help keep it supple and smooth. Aside all the anti-wrinkle properties the onion may offer, this versatile culinary plant can provide a real health boost to anyone. Furthermore, in addition to all the powerful nutrients it contains, onions top the list of vegetables that are least likely to contain significant amounts of pesticides and other harmful chemicals.