Nutrients are classed as either macronutrients or micronutrients:macronutrients are carbohydrates (sugars and starches), fats (including essential fatty acids), proteins (including essential amino acids), and fibermicronutrients are vitamins, minerals, and trace elements that cannot be manufactured in the body, and so must be eaten daily.If micronutritents are absent or too low, illness results. Scurvy, for example, is a disease resulting from lack of vitamin C. It used to be the curse of sailors who had to make long trips at sea with no access to fresh fruit or vegetables. Once the connection between scurvy and fresh fruit had been made, and the sailors issued lime juice to drink, scurvy virtually disappeared.Nutritional therapists assess nutritional status and functional capacity. They recognize that each person’s needs are unique, depending on a number of factors, from inherited strengths and weaknesses to the influence of diet, lifestyle and environment. Nutritional therapists work with clients with chronic health problems and provide advice on disease prevention and control.The nutritional therapist will take a comprehensive client history and may use biochemical and other types of clinical assessment to formulate a treatment plan. In addition to dietary and nutritional advice, recommendations may include guidance on natural detoxification, methods to support digestion and absorption, procedures to promote colon health, and also the avoidance of ingestion or inhalation of allergens or toxins.Nutritional therapy is a holistic discipline; nutrition as the key to good health is the all-embracing fundamental principle used since the time of the famous Greek doctor and founder of western medicine, Hippocrates, to help people of all ages to stay at their personal peak of energy and vitality. Today, new insights of food scientists play a significant role in the practice of nutritional therapy as preventative medicine.Micronutrients have only been identified extensively and researched since 1913 when an American biochemist, Elmer McCollum, discovered the first vitamin, vitamin A. Their use in treatment has now become a major, and rapidly growing, therapy in its own right throughout the world. Another nutritional therapy is megavitamin therapy, established by the Nobel prize winner Dr. Linus Pauling in the United States. He believed that schizophrenia and other mental problems were the consequence of vitamin deficiency and originally called his therapy "orthomolecular psychiatry. "The therapeutic prescription of nutrients is known as nutritional therapy, and practitioners specializing in it are nutritional therapists. Nutrients prescribed in this way are called "dietary" or "food supplements," and they come in the form of tablets, capsules, powders, or liquids. Nutrients may sometimes also be injected for greater effect, but in most countries only conventional medical doctors may do this.Nutritional therapists should:    * be able to get on well with clients from a wide range of backgrounds    * be able to gain clients' confidence    * have a logical approach to problem solving    * be able to maintain an emotional distance from clients' problems