An oral capsule containing curcumin, green tea extract, Polygonum cuspidatum extract, and soybean extract, with antioxidant and potential chemopreventive activities. The antioxidants in curcumin/green tea extract/Polygonum cuspidatum extract/soybean extract capsule bind to and neutraliize free-radicals, which may prevent their genotoxic and carcinogenic effects.