A research dietitian, or research nutritionist, is a professional employed to carry out a defined programme of nutritional research for a company, university, or institution. The work ranges from clinical trials testing a dietary intervention, through laboratory analysis of food composition, to population surveys of eating habits. Unlike a clinical dietitian treating patients, the research dietitian’s output is evidence: study protocols, datasets, and published findings that advance understanding or support product development and health claims. The role demands scientific rigour in study design, ethics approval, and statistics, plus the practical nutrition knowledge to make interventions realistic. Sponsorship by a food company brings particular duties of transparency, since the credibility of the findings depends on demonstrably independent methods.