Clinical Nutrition can be defined as the therapeutic use of nutrient-rich foods and nutritional supplements to improve health and prevent disease. It is essential to modify the diet to be as health-promoting as possible. This should be a priority and if necessary, an ongoing project, until the best outcomes have been achieved. Nutritional supplements are utilised therapeutically where applicable with the main aim being to achieve health through diet, reducing the need for supplement use. When diet continues to be inadequate to facilitate the healing process or prevent disease, then further supplementation or ongoing supplementation may be required. 

Currently the Naturopathic and functional medicine approach to clinical nutrition is distinctive, differing from clinical nutrition practiced by most medical doctors and dieticians, who typically apply cautious dietary modifications and very cautious nutrient supplementation, to correct nutrient deficiency states. Naturopaths and functional medicine practitioners recognise the value that nutrients have when they are provided in doses far greater than those found in foods, and their ability to address the individual biochemical needs of patients. The mounting evidence being generated in Orthomolecular medicine supports the use of such therapeutic doses that have now been used by Naturopaths for decades.

Strategies employed by most medical doctors and dieticians are sound, however not sufficient when treating patients wanting options other than pharmaceutical drug interventions or basic dietary guidance. It is common for patients with serious diseases, such as inflammatory bowel disease, multiple sclerosis, schizophrenia and various types of cancer, to require nutrient supplementation in amounts far greater than those achieved from diet alone, to mitigate symptoms and alleviate suffering.