Carbohydrates are present in food comprising of digestible sugars and starches and indigestible cellulose and other dietary fibres. The former are the major source of energy. The sugars are in beet and cane sugar, fruits, honey, sweet corn, corn syrup, milk and milk products, etc.; the starches are in cereal grains, legumes, tubers, etc. In patients with hepatic forms of porphyria, a person should consume at least 350 mg of carbohydrate per day, or the carbohydrates should make up 60-65% of the daily consumption. This book examines and presents new research of the complexity, effects and nutritional aspects of dietary carbohydrates.