Be very cautious about using dietary supplements while on active treatment for cancer. Several recent studies have shown that cancer patients taking antioxidants have had poorer outcomes than patients who did not. Consider that one of the ways chemo works is to deny cancer cells the necessary building blocks they need to divide and make more cells. By taking many vitamins and supplements at high doses, patients may be providing the cancer everything it needs to get “around” the chemo and survive. Herbal medications have the added potential to actually interfere or block the chemotherapy. A recent study that was attempting to show the benefits of green tea for cancer patients accidentally found that drinking green tea while taking chemotherapy actually inactivated the drug bortezomib. Without that study, the patients would have been unaware that the tea they were drinking was interfering with their chemo doses and rendering them harmless to the cancer.