Onion
Onions are high in antioxidants, such as quercetin, which have been shown to protect cells from damage caused by free radicals. Free radicals are molecules that can cause damage to cells and DNA, and they have been linked to a number of chronic diseases, such as cancer, heart disease, and Alzheimer's disease.
Onions contain sulfur-containing compounds, such as allicin and alliin, which have been shown to have anti-cancer properties. These compounds have been shown to inhibit the growth of cancer cells and to induce apoptosis, which is the programmed death of cells.