Sugar Part 2: Digestion and Absorption

The body digests and absorbs simple and complex carbohydrates differently.  Why would this information be useful to you?  Although there is a time and place for both types of sugar in the diet, the quantity and timing will change drastically depending upon your fitness and health goals.  For example, if you want to optimize your workout potential, you will have better physical and mental stamina by ingesting a small amount of simple sugars during the workout.  If your goal is simply to resist hunger pangs between breakfast and lunch, eating complex carbs in the morning will delay the speed at which sugar is absorbed, thereby making you feel fuller for longer.

Digestion and Absorption

Digestion is different from absorption.  Digestion is the route by which food and drink travel through the digestive tract (mouth, esophagus, stomach, small intestine, large intestine, rectum).  Absorption is the uptake and use of food and drink from the digestive tract.  Both simple and complex carbohydrates must be broken down into glucose before being absorbed into the body.  You can only absorb ONE FORM of sugar from your small intestines and into your bloodstream: glucose.  Glucose is a single molecule of sugar.

Simple Sugars

The body digests and absorbs simple sugars rapidly.  Simple sugars are only one-two molecule sugars. As a result, it takes little to no time for the body to break down simple sugars in the digestive tract.  As soon as you swallow orange juice, soda, or dried fruit, the sugar will move down your esophagus, through your stomach and quickly into the small intestine.  In the small intestine, the simple sugar is absorbed right away into the bloodstream.  Almost instantly, your blood sugar level rises.  The sugar can either be utilized by your muscle and brain cells for fuel, stored in the liver as glycogen, or in your adipose tissues as fat.

Complex Sugars

The body takes a longer amount of time to digest and absorb complex sugars because they have a long chain of molecules that take time to break down.  This is also because the two subgroups of complex sugars (starchy and fibrous) pack a lot of fiber per bite.  Fiber delays the time it takes for food to pass from the stomach to the small intestine.  The body cannot absorb fiber and so complex carbs move faster through the intestines and rectum. Starchy carbs include brown rice, potatoes, oatmeal, whole wheat pastas and whole grains. Fibrous carbs include vegetables like celery, asparagus, broccoli, cauliflower, onions, mushrooms, spinach, peppers and any dark leafy greens.

Now that you have a brief understanding about how simple and complex carbs are digested and absorbed, I will review practical applications of each tomorrow…


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