How Are Carbohydrates Digested?

Carbohydrates or "carbs" are the portion of a healthy diet that provides energy to the body for muscular work, breathing, and brain functions among other activities. Carbohydrates contain some sugars called saccharides. The sugars are often linked together and are referred to as polysaccharides. So, how are carbohydrates digested? The digestion process for carbohydrates starts in the mouth and is complete when polysaccharides are broken into monosaccharides, which are then absorbed in the body.

Types of Carbohydrates

The main types of carbohydrates are sugars, starches, and dietary fiber. When answering the question, "how are carbohydrates digested?" it is important to note that the body does not digest all types of carbohydrates. The body digests sugars and starches fully. When the two carbohydrates are absorbed, they provide 4 calories of energy per gram of carbohydrates. The human body lacks the necessary enzymes to digest or break down fiber. Consequently, fiber is eliminated from the body through excretion in large amounts.

How Are Carbohydrates Digested?

The digestion of carbohydrates takes place in different parts of the body. Below is a breakdown of the activities in different parts of the body, and the enzymes or acids that each parts releases.

1. Mouth

The digestion process begins in the mouth where saliva from the salivary glands moistures food. As we chew the food and break into smaller pieces, the salivary gland releases enzyme salivary amylase. This enzyme breaks down polysaccharides in carbohydrates.

2. Stomach

Carbohydrates are swallowed in small pieces mixed with enzyme amylase. This mixture is referred to as chyme. Chyme passes through the esophagus to the stomach. The stomach releases an acid that does not digest the chyme further but kills any bacteria in the food. In addition, the acid stops the function of the enzyme amylase.

3. Intestines

The pancreas releases pancreatic enzyme in the small intestine, which breaks down saccharides in carbohydrates into disaccharides. Disaccharides are also referred to as dual-molecule sugars. Sucrose is an example of a dual-molecule sugar. Other enzymes in the small intestine include lactase, sucrose, and maltase. These enzymes break down disaccharides into monosaccharides. Monosaccharides such as glucose are also known as single molecule sugars.

A report by the United Nations Food and Agricultural Organization indicates that the digestion of refined carbohydrates such as sugar and wheat flour is fast. The digestion of such carbohydrates occurs in the upper end of the small intestine. The digestion of complex carbohydrates such as whole grains occurs in the lower end of the small intestine near the ileum. The ileum and small intestine contain villi, which are finger-like protrusions that absorb digested foods. These protrusions vary depending on whether the carbohydrates in the diet are refined or whole grain.

4. Liver

The liver stores monosaccharides as fuel for the body. Sodium-dependent hexose transporter is a molecule that moves single glucose molecule and sodium ions into epithelial cells in the small intestine. According to Colorado University, sodium is exchanged with potassium in the bloodstream as the glucose transporter moves the glucose in the cells into the bloodstream. This glucose is stored in the liver and is released when the body requires energy for its functions.

5. Large Intestine or Colon

As indicated earlier, the body digests and absorbs all carbohydrates except dietary fiber and some resistant starches. The bacteria found in the large intestine releases enzymes that break down the indigestible carbohydrates. This digestion process in the colon produces short-chain fatty acids and gases. The bacteria in the colon consume some of the fatty acids for energy and growth while some are eliminated from the body with feces. Other fatty acids are absorbed into colon cells and a small amount is transported to the liver. The dietary fiber is slowly digested in the gastrointestinal tract compared to sugars and starches. Hence, consuming dietary fiber leads a slow and slight rise in blood glucose.

Simple and Complex Carbohydrates

We should include carbs in our diet always. However, we need to understand how our bodies use different categories of carbs including simple (or bad) carbs and complex (or good) carbs. After answering the question, "how are carbohydrates digested?" we can now differentiate between simple and complex carbohydrates, and determine which of two types is healthy.

Simple Carbohydrates

Simple carbohydrates are made of basic sugars that are easy to digest. These carbohydrates are of little value to the body. Carbohydrates with high sugar content and low fiber content are bad for your health.

Fruits and vegetables are in the same category as cookies and cakes. They are all simple carbohydrates. However, fruits and vegetables are different from other foods in this category as they contain fiber, which changes and slows down their digestion process in the body,which makes them very similar to complex carbohydrates.

Sources of simple carbohydrates: Some of the carbohydrates that you should avoid in your diet include soda, artificial syrup, candy, and sugar. Others include white rice, pastries, desserts, white bread and white pasta. You can enjoy any of these foods occasionally but they should not be the primary sources of carbs. Consuming baked potatoes, regular pasta, or white rice is better than consuming chips, cookies, or cakes.

Complex Carbohydrates

Complex carbohydrates are composed of longer series of sugars than simple carbohydrates. Hence, they are considered good carbs and take longer to digest. Complex carbohydrates have lower glycemic load. This means that small amounts of sugar are released in your body consistently throughout the day.

Choose the right food: You can include complex carbohydrates in your diet by substituting simple carbohydrates. For instance, you can choose brown rice over white rice. You can also choose whole-wheat pasta over white pasta.

Now that you know the answer to the question, "how are carbohydrates digested?" make the right choices when buying carbohydrates. Read the information on packages to determine if the food contains simple or complex carbs. Whole-grain, whole-oat, or fiber ingredients indicate that the food contains complex carbohydrates.