Curcumin is the primary chemical part of the spice turmeric (Curcuma longa). It has been shown to prevent stomach and colon cancers in rodents. Scientists have many theories as to how curcumin prevents cancer. But so far they have not reported whether curcumin affects the growth of the bacteria, Helicobacter pylori. This bacterium is a Group 1 carcinogen. It is linked with the growth of stomach and colon cancer. Two forms of tumeric were tested against 19 strains of H. pylori, including 5 cagA+ strains. These forms were the pure chemical, curcumin and an extract. The extract was made in the alcohol, methanol, from the dried powdered roots of the plant Curcuma longa. Both forms inhibited the growth of all strains of H. pylori grown in culture. The minimum inhibitory concentration ranged from 6.25-50 micrograms per milliliter. They concluded that curcumin inhibits the growth of H. pylori cagA+ strains grown in culture. They suggest that inhibition of H. pylori may be one of the ways by which curcumin prevents cancer.