Among the most important medicinal and culinary herbs in the world, turmeric imparts a glorious golden colour to foods, as well as a pleasantly earthy pungency - particularly when fresh. In Ayurvedic medicine it is a treatment for everything from cobra bites to bruises, and it is currently being widely investigated as a treatment for liver disease, cancer and Alzheimer's. The active ingredient and source of the rich colour is curcumin.