A nutritionist is a person who advises others on matters of food and nutrition and their impacts on health. Some people specialize in particular areas, such as sports nutrition, public health, or animal nutrition, among other disciplines. In many countries, a person can claim to be a nutritionist even without any training, education, or professional license, in contrast to a dietitian, who has a university degree, professional license, and certification for professional practice. The professional practice of being a dietitian (also spelled dietician in the US) is different from a nutritionist. In many countries and jurisdictions, the title nutritionist is not subject to statutory professional regulation; thus, any person may self-title as a nutritionist or nutrition expert, even if self-taught and professionally uncertified. In the United Kingdom, Australia, parts of Canada, and most US states, a person self-titled as a nutritionist is not legally defined, whereas a dietitian is professionally certified and registered. People who have current registration with the appropriate regulatory body usually refer to themselves as Registered dietitians, and so may use the professional designation, "RD" or "SRD". The term nutritionist may refer to a range of trained or untrained individuals – from someone who has no qualifications in nutrition to someone with a PhD in nutrition science. Within the professional field of nutrition, there is also the field of nutrition therapy which may be associated with practitioners of alternative medicine. Prominent examples include Gillian McKeith, Patrick Holford and Robert O. Young. A potential problem with self-proclaimed and media nutritionists, is low levels of training, the selling of supplements and herbal remedies and the use or promotion of concepts that are untested or potentially even dangerous, such as exclusion of food groups, detox and fad diets. To obtain the Nutritionist title, one must have studied at a recognized university for four years plus a year practice (internship).