Quercetin, the main ingredient in the skin of the onion is a powerful flavonoids – antioxidant that fights free radicals – main cancer causers.
According to studies, onion skin can be used as an excellent addition to any diet because its high content of insoluble fiber, which is excellent for regular and normal peristaltic movements of the colon.
Additionally, these insoluble fiber helps to remove all toxins from the intestines and to balance the pH value. Prevents formation of cancerous cells.
Note: Onion skin is not recommended for pregnant women and nursing mothers. finelivingadvice.com