Registered Dietitian Quiz Pro

Registered Dietitian Quiz Prep Pro

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", which is otherwise exclusively used to refer to specialists and practitioners of other professions.[5][6] 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.[7][8]

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[9][10][11] 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.[5][12]

As explained in a 2010 newsletter[13] of the International Confederation of Dietetic Associations:

The correct or preferable spelling of the term "dietitian" has been debated for a long time by dietitians. In the early 1960s dietetic associations, under the auspices of the International Committee of Dietetic Associations (ICDA), worked together to standardize information about dietitians under the International Standard Classification of Occupations. When the International Labour Office confirmed the dietetic profession's classification in 1967, it also adopted the spelling "dietitian" at the request of the international dietetic community. This information can be found in the documentation held by ICDA and by the International Labour Office (ILO).

Recently the ILO has however issued new documents using the spelling "dietician".[13]