The outer papery layer of an onion is full of QUERCETIN.
What’s Quercetin? It’s an anti-inflammatory and antioxidant. Research suggests Quercetin has anti-cancer and neuroprotectic benefits.
How to use: To benefit from the quercetin in onion skins, you can include them in your cooking by adding whole onions (skins and all) to broths, soups, or stews. The skins can also be saved and dried in a paper bag for later use.
Onion skins are a concentrated source of flavonoids, especially quercetin.