The paper analyzes the clinical efficiency and safety of specialized medical nutrition therapy in patients with Stage IVA laryngeal cancer, T4_aN₀M₀, during complex surgical treatment followed by polychemotherapy. For diet therapy, a new dietary supplement for therapeutic and preventive nutrition, such as Protein Detox Smoothie and Recovery Protein Smoothie for cancer patients, produced by the Russian company LEOVIT Nutrio was added to the standard diet for these patients. The above multicomponent dietary supplements that are balanced in essential macronutrients and micronutrients and contain plant components, contributed to a rapid postoperative restoration of physical activity in 70% of patients; a decrease in the general toxic side effects of chemotherapy; a decline in the number of appetite loss complaints in 50% of patients; changed food intake attitudes that appeared as a desire to eat more frequently; a rapider appearance of a feeling of hunger in 70% of patients, a considerable reduction in nausea in two-thirds of patients), and stoppage to lose body weight in 60%. Dietary detoxification supplementation has a positive impact on the blood concentration of the most important antitoxic liver protection enzymes, such as ALT and AST, γ-HT, total and conjugated bilirubin, and urea, promotes an increase in the blood concentrations of total protein, albumins, α1- and α2-globulins, as well as γ-globulins by 26%; and reduces the levels of the major inflammatory marker C-reactive protein. Specialized dietary supplements are recommended for patients during their disease, after surgery, chemotherapy and radiotherapy, as well as in the rehabilitation period after hospital discharge.