Jun J. Mao, MD of Memorial Sloan Kettering Cancer Center explains why oncologic supplements and diet correlative evidence is incomplete and how physicians should emphasize safety first. As an integrative oncology specialist, a lot of patients came to him and asked what kind of supplements to eat or diet to implement. However, he emphasizes that the evidence of this correlation is incomplete, and the best thing to keep in mind is Safety First. He notes that patients should select supplements and herbs that many not interact with the chemotherapy, radiotherapy and other therapy. Balanced diet or more plant-based diet is associated with the overall health and some cancer outcomes. However, there is still no convincing evidence, even up to this day, that specific vitamins and supplementation that can actually improve cancer outcome. In fact, the opposite is true. So, he warns patients to be very careful.