CLL-IMPACT: A Clinical Nutrition Trial Investigating Immune and Metabolic Changes in Early-Stage CLL

The goal of this clinical trial is to investigate whether a short-term (4-week) whole-food, plant-based (WFPB) diet has an effect on metabolism, immune function, and disease activity in early-stage chronic lymphocytic leukemia (CLL). The main questions the study aims to answer are: * Does a WFPB diet influence disease progression? * How do CLL cells and other immune cell types respond to a WFPB diet in terms of metabolism and signaling? Researchers will examine whether a WFPB diet can affect absolute lymphocyte counts in participants' blood and what metabolic or functional changes occur within the CLL cells. Participants will: * Switch to a WFPB diet for 4 weeks following an introductory session with a certified dietary instructor. * Visit the clinic before starting the diet and again after 14 and 28 days for blood draws and to provide stool samples. * Keep a diary of all foods and drinks consumed during the week prior to and throughout the study period.