A natural substance that comes from the underground stem of an East Indian plant called turmeric, or Curcuma longa, and gives turmeric its yellow color. The turmeric plant has been used for many years in traditional Asian medicine to treat certain conditions. Curcumin, which is found in turmeric, may have antioxidant and anti-inflammatory effects in the body. It is being studied in the prevention and treatment of some types of cancer.