Enzymes are specialized protein molecules that catalyze chemical reactions in biological systems without being consumed. If not for enzymes, some vital processes could not occur within your body. Digestive enzymes are responsible for breaking down the foods you eat, so that they can be absorbed through your intestinal lining. Different kinds of digestive enzymes are specifically designed to address the three types of macronutrients: carbohydrates, proteins and fats. Some of these enzymes begin to digest your food as soon as you put it in your mouth.
Carbohydrases
Carbohydrates include sugars, starches, celluloses, hemicelluloses and fiber. Some carbohydrates, such as glucose and fructose, are simple sugars and require no further digestion prior to absorption. Others, such as cellulose or pectin, are more complex and must be sequentially attacked by different enzymes before their elementary constituents can be absorbed. Carbohydrases are carbohydrate-digesting enzymes; they include amylase, maltase, sucrase, lactase, pectinase and invertase. Salivary amylase, produced by glands in your mouth, is one of the first digestive enzymes encountered by your food.
Proteases
Proteins, which break down proteins, are composed of chains of basic building blocks called amino acids. Dietary proteins can be amazingly complex structures, but they must be reduced to constituent amino acids before they can be assimilated into your bloodstream. This process begins in your stomach, where hydrochloric acid, pepsin and an array of proteases cleave large proteins into smaller segments called peptides. Protein digestion continues in your small intestine, as pancreatic proteases, trypsins, peptidases and amino peptidases eventually reduce the peptides to amino acids, which can be absorbed.
Lipases
According to Dr. Elson Haas, author of "Staying Healthy with Nutrition," lipids, or fats, are more resistant to digestion than carbohydrates or proteins. This stems, in part, from their inherent insolubility in your gastrointestinal tract, which is an aqueous environment. Lipases are the enzymes that break down fats. According to a 1977 study in "Laboratory Investigation," fat digestion begins in your mouth, where lingual lipase begins to break dietary fats into their constituent parts, which include monoglycerides, diglycerides, glycerol and free fatty acids. This activity continues in the stomach and small intestine, where the lipids are exposed to gastric lipase and pancreatic lipase, respectively. Bile acids serve an important role in the digestive process, as they emulsify the fats and further expose them to enzymatic activity.
Considerations
Digestive enzymes are normally produced in your gastrointestinal tract in response to the ingestion of food. Different enzymes are responsible for digesting the three classes of macronutrients. Some diseases, such as chronic pancreatitis or cystic fibrosis, interfere with the production of digestive enzymes. Individuals affected by these conditions often require digestive enzyme supplements. People with Crohn's disease, celiac disease and other conditions often use digestive enzyme supplements; if you suffer from such a medical condition, consult your doctor to see if digestive enzymes are appropriate for you.
References
- "Staying Healthy with Nutrition: Lipids -- Fats and Oils"; Elson M. Haas; 2006
- "Laboratory Investigation"; Lipolytic Activity of Human Lingual Glands (Ebner); M. Hamosh and W.A. Burns; December 1977
- "Current Treatment Options in Gastroenterology"; Pancreatic Enzyme Supplementation Therapy; J. Keller and P. Layer; October 2003
