How Do Carbs Work In The Body?

It's easy to take plants for granted. Yet your day-to-day existence is possible largely because plants provide the carbohydrates your body needs to generate the energy necessary for survival. Carbohydrates include sugars, starches and plant fiber. Your body uses sugars and starches for energy. Plant fiber cannot be used to generate energy but serves other important functions that contribute to your good health.

Glucose

Your body can only absorb single sugar molecules. Enzymes in your digestive tract break down dietary sugars and starches into the single sugars glucose, galactose and fructose. Glucose is your body's favored sugar in terms of energy production. Free glucose from your diet is absorbed from your small intestine and enters your cells with the help of the hormone insulin. Insulin deficiency or resistance is the hallmark feature of diabetes mellitus. Once inside your cells, glucose undergoes a chemical process called glycolysis, which simultaneously breaks down the sugar and generates the energy needed to keep your body functioning. Although glycolysis can occur with or without oxygen, more energy is produced when this process occurs in the presence of oxygen.

Galactose

The milk sugar lactose breaks down into glucose and galactose in your small intestine. Once in your bloodstream, galactose is absorbed into your cells. A series of enzymatic chemical reactions convert galactose into a form of glucose that can enter into the energy-generating pathway. Genetic mutations that disrupt the conversion of galactose to glucose lead to a condition called galactosemia. A lifelong, low-galactose diet is the primary form of treatment for galactosemia.

Fructose

Fructose is a naturally occurring sugar in fruit and vegetables. It is also found in a variety of processed foods as an added sweetener. Fructose passes from your intestines to your bloodstream. It is taken up primarily by your liver and muscle cells. Inside your muscle cells, fructose can be used to generate energy through glycolysis. In your liver, fructose can be used for energy generation or the production of fats called triglycerides. Your liver cells export triglycerides, which travel to your fat cells for storage.

Fiber

Plant fiber consists of tightly bound sugar molecules that your digestive enzymes cannot sever; therefore, carbohydrates in the form of fiber travel through your digestive tract essentially unchanged. Plant fiber, however, benefits you because it binds cholesterol, reducing the amount absorbed into your bloodstream. It also adds bulk to your stool, which keeps your bowels moving regularly. Recommended daily fiber intake is 14 g per 1,000 calories consumed.