The notion that a particular diet, for example, can cause, or cure, cancer is ubiquitous but erroneous. Some foods are known carcinogens, such as alcohol and processed meat, with heavy consumption of the latter increasing absolute risk for colorectal cancer over a lifetime by approximately 1 percent. But there are no miracle diets that cure cancer, nor is any particular diet responsible for it. In a 2023 article in the Lancet Oncology, surgeon and cancer survivor Elizabeth O’Riordan and I delved into the disturbing prevalence of dietary myths surrounding cancer. Assertions that sugar or carbohydrates “feed” cancer feature prominently, giving rise to the related claim that high-protein ketogenic or all-meat diets cure it. At the complete opposite end of the nonsense spectrum, others insist that acidity enables cancer cells to take hold, advocating alkaline or vegan diets to stave off disease.