Randomized Trial of Mediterranean Diet During Chemotherapy for Early Breast Cancer Evaluating Effects on Gut Microbiome, Immune Function, and Quality of Life Considering Socioeconomic Factors

What this Trial Is About

This research investigates whether following the Mediterranean diet can affect the gut microbiome, quality of life, well-being, immune activity, and treatment outcomes in patients with early breast cancer undergoing neoadjuvant chemotherapy. The study also examines if these effects are stronger among patients facing challenging socioeconomic conditions. The Mediterranean diet emphasizes plant foods, such as vegetables, fruits, nuts, seeds, berries, legumes, herbs, and spices, with animal proteins like fish, meat, and cheese, and olive oil as the main fat source. Breast cancer is common and serious, and socioeconomic factors influence patient outcomes. Participants will be randomly assigned in a 21 ratio to either follow the Mediterranean diet with personalized guidance from a nutrition therapist aiming for daily intake of 30 grams of dietary fiber and 30 different plant foods per week while minimizing ultra-processed foods, or to continue their usual diet. Nutritional support includes weekly sessions during chemotherapy visits or via online or home visits, access to educational materials and recipes, and group sessions. The study period covers from before chemotherapy start until the beginning of the sixth chemotherapy cycle, with sample collections and assessments scheduled throughout. During the study, patients will provide stool and blood samples for microbiome and immune system analysis, complete questionnaires on quality of life and well-being, and record their dietary intake using an app and paper logs. Researchers will monitor immune cells, short-chain fatty acids, socioeconomic data, and clinical outcomes including survival and cancer recurrence for up to 10 years. Safety is expected to be minimal due to the nature of the dietary intervention, and participants may stop the trial at any time while continuing their usual medical care.

Mediterranean Diet and Inequality in Early Breast Cancer