A dietitian or dietician is an expert in identifying and treating disease-related malnutrition and in conducting medical nutrition therapy, for example designing an enteral tube feeding regimen or mitigating the effects of cancer cachexia. Many dietitians work in hospitals and usually see specific patients where a nutritional assessment and intervention has been requested by a doctor or nurse, for example if a patient has lost their ability to swallow or requires artificial nutrition due to intestinal failure. Dietitians are regulated healthcare professionals licensed to assess, diagnose, and treat such problems. In the United Kingdom, dietitian is a 'protected title', meaning identifying oneself as a dietitian without appropriate education and registration is prohibited by law.
A registered dietitian (RD) (UK/USA) or registered dietitian nutritionist (RDN) (USA) meets all of a set of special academic and professional requirements, including the completion of a bachelor's and/or master's degree in nutrition and dietetics (or equivalent). One or more internships (USA) or clinical placements (UK) must also be completed. These may be allocated and monitored by the university as part of the structured degree programme (UK) or may be applied for separately (USA).
Roughly half of all RD(N)s hold graduate degrees and many have certifications in specialized fields such as nutrition support, sports, paediatrics, renal, oncological, food-allergy, or gerontological nutrition. Although assessment priorities differ depending on the specialist area, a patient's medical and surgical history, biochemistry, diet history, eating and exercise habits usually form the basis of assessment. The RD(N) negotiates a treatment plan with the patient which may include prescriptions, and follow-up visits often focus on maintenance and monitoring progress.
Most RDs work in the treatment and prevention of disease (administering medical nutrition therapy, as part of medical teams), often in hospitals, health-maintenance organizations, private practices, or other health-care facilities. In addition, many registered dietitians work in community and public-health settings, and/or in academia and research. A growing number of dietitians work in the food industry, medical corporations, journalism, sports nutrition, corporate wellness programs, and other non-traditional dietetics settings.
The spellings "dietitian" and "dietician"
As explained by the American Heritage and Merriam-Webster's dictionaries, the cause of the confusion is that the spelling with "-tian" is an irregular alteration of the ending "-cian". These and other American dictionaries also list the spelling with "c" but list the spelling with "t" first because this spelling is more common in the United States. Nevertheless, the American publisher McGraw-Hill exclusively uses the spelling with "c" in the 2003 edition of the McGraw-Hill Dictionary of Scientific & Technical Terms and the 2002 edition of the McGraw-Hill Concise Dictionary of Modern Medicine.
The spelling with "t" is the one preferred by the profession itself internationally, but the spelling with "c" is used often enough in texts not written by members of the profession to be considered a valid variant by both American and British dictionaries. In fact, British dictionaries list the spelling with "c" first and list the spelling with "t" as a variant. American dictionaries list the spelling with "t" first and the spelling with "c" as a variant.
As explained in a 2010 newsletter of the International Confederation of Dietetic Associations: