Challenges of Conducting Clinical Trials of Natural Products to Combat Cancer
Why Natural Products Fail to Gain Regulatory Approval
To date, the FDA has not approved any food or dietary supplement as a drug for cancer prevention or treatment. The simple explanation for this is that no phase 3 clinical trial of a dietary supplement or food has shown sufficient efficacy and safety in preventing or treating cancer. What is striking is that there have been so many phase 2 trials with promising results and so few follow-up phase 3 trials. A likely explanation is that manufacturers of dietary
supplements perceive a positive phase 2 trial result as sufficient to promote their product without having to go through the rigor and expense of a randomized, placebo controlled
phase 3 trial.