Nutritionists aren't qualified to give clinical advice in relation to health. Properly qualified nutritional therapists, as well dieticians, are. Obviously you should steer clear of anyone who makes wild claims about curing incurable diseases. A properly qualified and registered nutritional therapist shouldn't do that and should be able to tell you the scientific basis for what they're recommending. The Nutritional Therapy Council (NTC) www.nutritionaltherapycouncil.org.uk/ntcaims.htm was set up by the government to regulate the profession and, hopefully, drive out amateurs spouting hocus pocus nonsense. A therapist's qualifications should meet the NTC's minimum educational standards and their website lists those courses which do. The standards demand an evidence-based approach to nutritional therapy and a level of competency which ensures safe and effective practice (which takes years of study equivalent to a degree and certainly could not be achieved by a short correspondence course). They also require registered therapists to undergo continual training in the form of continuous professional development so that they stay up to date. A properly qualified nutiritional therapist will also be registered with the British Association of Nutritional Therapists (BANT) www.bant.org.uk/bant/jsp/aboutBant.faces. This is the professional body for nutritional therapists. They too advocate an evidence-based approach and define nutritional therapy as the application of nutritional science to health promotion, disease prevention and peak performance. No wild claims there. BANT is recognised by and works in partnership with the Nutritional Therapy Council.