The goal of this clinical trial is to compare the effect of a Food for Special Medical Purposes (FSMP) mainly containing amino acids and flavonoids in combination with nutritional counseling, versus nutritional counseling alone, on chemotherapy toxicity, nutritional status and quality of life in patients with breast cancer. The main questions it aims to answer are: * can this dietary supplementation affect the nutritional status of breast cancer patients? * can this dietary supplementation have any beneficial effect on chemotoxicity? Participants will be asked to undergo nutritional counseling and to take the study product every day for 12 weeks. Researchers will compare a similar group of participants only receiving the nutritional counseling to see if any difference occurs.