Dietitian

A dietitian (sometimes spelled dietician, although the official spelling is Dietitian) is an expert in food and nutrition. Dietitians help promote good health through proper eating. They also supervise the preparation and service of food, develop modified diets, participate in research, and educate individuals and groups on good nutritional habits. The goals of the dietary department are to obtain, prepare, and serve flavorsome, attractive, and nutritious food to patients, family members, and health care providers.
In the US nutrition professionals include the registered dietitian (RD) and the dietetic technician, registered (DTR). These terms, as well as simply dietitian, are legally protected terms regulated by the American Dietetic Association (ADA). Some RDs or DTRs call themselves nutritionists. However, the term nutritionist is not regulated, as dietitian is. People may call themselves nutritionists without the educational and professional requirements of registered dietitians. Dietetic technicians are not the same as dietitians in terms of responsibilities and qualifications. Different professional terms are used in other countries.
In the U.S., dietitians are registered with the Commission on Dietetic Registration (the certifying agency of the ADA) and are only able to use the label "Registered Dietitian" when they have met strict, specific educational and professional prerequisites and passed a national registration examination