Sucrase is a digestive enzyme that plays a specific role in the human body. This enzyme is responsible for breaking down a particular type of sugar, making it available for the body to use. Understanding its function provides insight into how the body processes certain carbohydrates from the diet.
Understanding Sucrase and Sucrose
Sucrase is an enzyme, a protein that speeds up chemical reactions in the body. It is a disaccharidase, meaning it acts on disaccharides, which are sugars made of two simpler sugar units. Sucrose, commonly known as table sugar, is the specific disaccharide that sucrase acts upon. Sucrose is composed of one molecule of glucose and one molecule of fructose chemically bonded together.
The Process of Sucrose Digestion
The primary function of sucrase is to catalyze the hydrolysis of sucrose. Hydrolysis is a chemical reaction where water is used to break a molecular bond. When sucrose enters the small intestine, sucrase binds to the sucrose molecule at a specific active site.
This binding action stresses the bond linking the glucose and fructose units within the sucrose molecule. The bond then breaks, releasing glucose and fructose as separate monosaccharides. This breakdown is essential because the body cannot directly absorb the larger sucrose molecule.
Sucrase’s Role in the Body
Sucrase performs its function primarily in the small intestine. It is located on the brush border, a specialized surface made of microscopic projections called microvilli that line the intestinal cells. This location allows sucrase to efficiently break down dietary sucrose as food passes through the small intestine.
Once sucrose is broken down into glucose and fructose, these simpler sugars can be absorbed. They pass through the intestinal wall and enter the bloodstream. From the bloodstream, glucose and fructose are transported to cells throughout the body, where they are utilized as a primary source of energy for various metabolic processes.
When Sucrase Activity is Impaired
When sucrase activity is reduced or absent, the body struggles to properly digest sucrose. One such condition is congenital sucrase-isomaltase deficiency (CSID), a genetic disorder where the enzyme is not produced effectively. Acquired sucrase deficiency can also occur due to damage to the intestinal lining from conditions like celiac sprue or other inflammatory bowel issues.
If undigested sucrose remains in the small intestine, it cannot be absorbed and proceeds to the large intestine. In the large intestine, this undigested sugar draws excess water into the bowel, leading to a type of watery diarrhea. Bacteria naturally present in the large intestine then ferment the undigested sucrose, producing gases that can cause bloating and abdominal pain.
Common symptoms of impaired sucrase activity include chronic watery diarrhea, abdominal discomfort, gas, and bloating after consuming sucrose-containing foods. In infants and children, this can sometimes lead to poor physical growth or malnutrition if not managed.