Broccoli

Broccoli provides 89mg of vitamin C and 2.6g of dietary fiber per 100g, along with indole-3-carbinol and sulforaphane—compounds with extensively studied cancer-preventive mechanisms. The American Cancer Society ranks cruciferous vegetables like broccoli among the most important dietary choices for reducing cancer risk. It delivers 30% more vitamin C per calorie than the average fruit, and its sulforaphane content can be boosted by 300% when chopped and rested for 40 minutes before cooking.