Nutrition is an important part of supportive cancer care. A registered dietitian can help maintain weight and muscle, manage side effects (nausea, taste changes, mouth sores, diarrhea, poor appetite), and prevent malnutrition, which is common and worsens outcomes. General guidance favors a varied diet rich in vegetables, fruits, whole grains and adequate protein, limiting processed and red meat and alcohol — the same pattern linked to lower cancer risk. However, popular claims that specific foods, juices, extreme fasting, or restrictive diets (e.g., very-low-carbohydrate/ketogenic or “alkaline” diets) can cure cancer are not supported by strong evidence, and severe restriction during treatment can cause dangerous weight and muscle loss. Some supplements and “superfood” regimens can also interfere with treatment. Nutrition should be individualized with the care team, especially during active treatment.
A registered dietitian (ideally one experienced in oncology) assesses needs and tailors a plan — adjusting calories, protein, texture and timing around treatment and symptoms, and advising on safe food handling when immunity is low. They also review supplements for interactions.
Nutritional needs change through treatment and recovery. The goal is maintaining strength and function, not restrictive dieting. Nutrition supports treatment; it does not replace it.