If you’re diabetic or closely watching carbohydrates in your diet for other reasons, you’ll need to know how your body uses them. Your digestive tract works hard to break down carbohydrates. It’s a long process, full of a series of biochemical actions that begin in your mouth. Many organs play roles in digesting carbohydrates and the various types of carbs are processed differently.
Types of Carbohydrates
Generally carbohydrates fit into either the simple or complex category. Simple carbohydrates are fructose, galactose, maltose and all other types of sugars. Complex carbs are starches, which are like tightly wound balls that need to be deconstructed before your body can use them. Both simple and complex carbohydrates wind up as glucose in the end. Glucose is the main energy source for every cell throughout your body and the preferred type of fuel for brain cells. Your body can break down fat and protein for energy if carbohydrates aren’t available, although these are an absolute last resort.
While your mouth isn’t technically an organ, it is the place where carbohydrate digestion first begins. When you chew, sugar molecules head right down into your digestive tract, but starch compounds need the help of saliva in your mouth. Saliva breaks apart complex starch molecules, making it easier for digestion in your stomach.
After you swallow your food, digestive juices in your stomach go to work. Stomach muscles and acids activate and blend all of the food compounds, including carbohydrates, breaking them up as much as possible. Your stomach can hold on to food if your intestinal tract is backed up, although once your stomach is done mixing, it’ll send everything off to your small intestine eventually. Carbohydrates are the first thing to go, while protein and fat tend to sit in there a bit longer.
The Small Intestine and Pancreas
Once those broken down carbohydrates hit your small intestine, your pancreas releases enzymatic juices that finish up the deconstruction process. Simple carbohydrates quickly get turned into glucose and absorb right through intestinal walls directly into your bloodstream. The previously complex starch molecules undergo one more step. The enzymes turn the complex compounds into maltose, a type of simple carbohydrate. From there, maltose quickly transforms into glucose and gets sent into your bloodstream.
When glucose reaches your blood, the hormone insulin opens up cells so they can pull in the glucose for fuel. Whatever glucose is left over travels to your liver for storage. Your liver turns glucose into glycogen and hangs onto it or sends some over to your muscles for storage, until your blood glucose levels drop. Glycogen quickly turns back into glucose if your body suddenly needs energy.
Your colon, or large intestine, takes on any extra food components – like fiber – that are not absorbed. Fiber is a type of carbohydrate that isn’t converted into glucose. It travels through your gut intact, acting like a broom along the way. Although fiber does not give you energy, it does keep your bowels moving so sugar, starch and all other nutrients can reach intestinal walls for absorption. Once fiber reaches your colon, it continues to sweep away any extra waste your body doesn’t need, producing stools and keeping you regular.
Melodie Anne Coffman specializes in overall wellness, with particular interests in women's health and personal defense. She holds a master's degree in food science and human nutrition and is a certified instructor through the NRA. Coffman is pursuing her personal trainer certification in 2015.