Abstract Modern cancer pharmacotherapy consists of contributions from natural products, their structural analogues, and chemotherapies. Interest in natural products is being revitalized in oncology. Natural products may be classified as food, dietary supplements, drugs, or cosmetics depending on their intended use. A natural product intended to prevent, diagnose, cure, mitigate, or treat disease would be regulated as a drug. Most natural products are regulated as dietary supplements, intended to affect the structure or function of the body. In 2023, Americans spent around $58 billion on dietary supplements, with a majority intended to prevent or treat cancer. Almost 50% of newly diagnosed patients with cancer report taking dietary supplements after diagnosis. Botanicals, natural products made from plants, plant parts, or plant extracts, are one of the most highly-used supplements. The natural product market is zealous to promote their supplements and often claim their products will help in combatting disease. Unlike with FDA-approved drugs, botanical dietary supplements may be marketed without proving they work as claimed and do not require clinical trials. To date, only four botanical drug products have been approved for marketing as prescription drugs in the U.S. Here, we evaluate the current paradigm for dietary supplement marketing and FDA approval and its impact on the treatment of patients with cancer. We underscore the need for rigorous clinical trials for clinicians to access sufficient evidence-based data to advise on the safety and efficacy of these products, alone or in conjunction with active treatment for cancer.