 We are increasingly aware of plant-derived substances that act as chemo-preventive agents, substances that help prevent cancer, as opposed to chemotherapy, substances aimed at treating cancer. These substances are not only inexpensive, they're easily available of no or limited toxicity. Since 1987, the National Cancer Institute has tested more than a thousand different potential agents for chemo-preventive activity, of which only a few dozen were moved to clinical trials. Curcumin, present in the Indian spice turmeric, which is used in curry powder, is one such agent that is currently under clinical investigation for cancer chemo-prevention. According to their mode of action, chemo-preventive agents are classified into different subgroups. There's the anti-proliferatives, antioxidants, or carcinogen blockers. Curcumin belongs to all three, given its multiple mechanisms of action. Curcumin appears to play a role, helping to block every stage of cancer transformation, proliferation, and invasion. It may even help before carcinogens even get to our cells. A study back in 1987 investigated the effects of curcumin on the mutagenicity, the DNA mutating ability of several toxins. And they found that curcumin was an effective anti-mutagen against several environmental and standard mutagenic and cancer-causing substances. But this was in vitro, from the Latin meaning in glass, meaning in a test tube or P2 dish. What about in people? Well, it's not like you can take a group of people and expose them to some nasty carcinogens, just so you can give half of them turmeric and see what happens. Well, you could wait until some toxic waste spill happens or nuclear accident, but otherwise you're not going to find people who would voluntarily expose themselves to carcinogens. Unless smokers. We can just test it on smokers. They've got carcinogens coursing through their veins every day. If you take some smokers, have them pee on some bacteria, this is the number of DNA mutations that arise. Remember, all life is encoded by DNA, whether bacteria, banana, or bunny rabbit. It's easier, though, when measuring urinary mutagens to just pee on some bacteria. The urine of non-smokers caused far fewer DNA mutations. Makes sense if fewer toxins running through their system. And if you have the non-smokers eat turmeric for a month, nothing really happens. What if you do the same for smokers, though? 15 days later they're down to here, 30 days they're down to here. And this is not some concentrated curcumin supplement. This is just plain turmeric, like you'd buy at the store, and less than a teaspoon a day. Indicating that dietary turmeric is an effective anti-mutagen. You'll note, though, on this graph, there's an even more effective anti-mutagen, not smoking. Even eating turmeric for a month, the DNA-damaging power of smoker pee exceeded that of non-smokers.