ABSTRACT
Carbohydrates are simple sugars or polymers of sugars that can be hydrolyzed to simple sugars by the action of enzymes in the digestive system. Dietary carbohydrate presently comprises 40-45% of the calories consumed by the average American and consists of 60% starch, 30% sucrose, and 10% lactose. Sucrose (table sugar) and lactose (milk sugar) are disaccharides composed of glucose and fructose (sucrose) and glucose and galactose (lactose). About half of the ingested carbohydrate is digested to glucose and the rest mainly to fructose and galactose. The principal product of carbohydrate digestion and the principal circulating sugar is glucose, which is taken up by the body cells and metabolized for energy. The normal fasting level of glucose in peripheral venous blood, determined by the highly specific glucose oxidase method, is 60-80 mg/dl. In arterial blood, the glucose level is 15-30 mg/dl higher than in venous blood.
