Leeks may taste similar to onions, they are actually related to the asparagus family. They originated in The Mediterranean and Asia but are now also grown in more temperate parts of the world. These veggies contain anti-cancer compounds called kaempferol (which is also known for promoting cardiovascular health) and quercetin (which is known to inhibit carcinogenic development in the body). These compounds are especially beneficial in fighting against prostate and colon cancers.
Hmm now I know why source got me to plant a few rows of them this spring. Never planted them before. Now I know why.