Roots and prepared ground powder of turmeric, Curcuma longa, a member of the ginger family, Zingiberaceae. The picture shows the ground spice of commerce in the foreground, together with pieces of the intact root in the background. The spice is prepared by boiling, then drying and grinding the roots. Turmeric has been used in Asian cookery for thousands of years; it is also used as a dye, producing a bright warm yellow hue, which is not light-fast. It contains curcumin (diferuloylmethane) which is claimed to have a wide range of potential health benefits for conditions such as diabetes, liver damage, Alzheimer's disease and dementia, and some cancers. Research on the health benefits of curcumin is promising, but these have mainly been demonstrated on laboratory animals. Large scale double blind testing on human subjects is so far lacking