The Role and Importance of Pancreatic Amylase in Digestion

Pancreatic amylase is a pivotal enzyme produced by the pancreas, vital for the digestive process. Its primary role is to break down carbohydrates into simpler sugars, facilitating their absorption by the body. Specifically, pancreatic amylase targets starches, converting them into maltose and glucose. These simpler sugars are crucial for energy production and maintaining bodily functions.

The production of pancreatic amylase begins in the pancreas, an organ located behind the stomach. When food, especially carbohydrates, enters the small intestine, the pancreas releases amylase through the pancreatic duct into the duodenum, the first segment of the small intestine. This release is triggered by the presence of food, signaling the pancreas to secrete amylase to aid in digestion.

Pancreatic amylase functions optimally in the slightly alkaline environment of the small intestine. This environment allows the enzyme to efficiently break down complex carbohydrates into simpler sugars that can be easily absorbed into the bloodstream. This breakdown process is essential for maintaining normal blood sugar levels and providing a consistent supply of energy to the body.

Disruptions in the production or function of pancreatic amylase can lead to significant digestive issues. For example, low levels of this enzyme can result in malabsorption of carbohydrates, leading to symptoms such as bloating, gas, and diarrhea. Conversely, elevated levels of amylase in the blood can indicate pancreatic disorders, such as pancreatitis or pancreatic cancer, conditions that require timely medical intervention.

Recent studies have highlighted the role of pancreatic amylase beyond mere carbohydrate digestion. It is now understood that variations in amylase levels can be linked to genetic factors and overall metabolic health. As research progresses, the precise mechanisms by which pancreatic amylase influences digestive and metabolic functions continue to be explored. Overall, pancreatic amylase is essential for proper digestion and metabolic health, underscoring the critical role of the pancreas in the digestive system.
The Role and Importance of Pancreatic Amylase in Digestion

Sucrose nutrition

Sugars are categorized as monosaccharides or disaccharides. Disaccharides are made up of two linked monosaccharides and are broken back down into monosaccharides during digestion.

Sucrose is a disaccharide, that it has made up of two linked monosaccharides. Specifically, it is composed of one glucose and one fructose molecule, 50% fructose and 50% glucose.

Sucrose is commonly known as “table sugar” but it can be found naturally in fruits, vegetables, and nuts. However, it’s also produced commercially from sugar cane and sugar beets through a refinement process. Sucrose is also added to many processed foods, such as candy, ice cream, breakfast cereals, canned foods, soda, and other sweetened beverages. Regardless of its source, sucrose provides four calories per gram.

The enzyme sucrase, which is made by the lining of human small intestine, splits sucrose into glucose and fructose. The glucose and fructose are then absorbed into the bloodstream.

Glucose ultimately gets taken up by cells with the help of insulin, while fructose is handled in the liver and does not need insulin to be absorbed.

Too much glucose means the body may experience complications with blood sugar levels. The presence of glucose increases the amount of fructose that is absorbed and stimulates the release of insulin. Excessive absorption of fructose can promote the increased creation of fat stores in the liver.

Eating fructose and glucose together may harm human health more than eating them separately. Consuming sucrose and high fructose corn-sweetened beverages increases liver fat and decreases insulin sensitivity. Decreased insulin sensitivity is a risk factor for Type 2 diabetes.
Sucrose nutrition

Digestive enzymes

Digestive enzymes are often used to support healthy digestion and increase nutrient absorption. Naturally occurring digestive enzymes are proteins that human body makes to break down food and aid digestion. Digestion is the process of using the nutrients found in food to give body energy, help it grow and perform vital functions.

Digestive enzymes are secreted (released) by the salivary glands and cells lining the stomach, pancreas, and small intestine. Their primary role is to help break down the large, complex molecules that make up proteins, carbohydrates, and fats, so that they are small enough for the body to extract and absorb the necessary nutrients.

When the body doesn't make enough enzymes, it can't easily break down foods and absorb nutrients. This is called malabsorption. If human body doesn’t make enough lipase, fat can’t be broken down. Then the body can’t absorb fat-soluble vitamins A, D, E, and K. Likewise, if frequent diarrhea happened because of improper digestion, the patient likely lose electrolytes and water-soluble vitamins.

There are many digestive enzymes. The most important digestive enzymes made in the pancreas include:
*Amylase
*Lipase
*Protease

Some other common enzymes are made in the small intestine, including:
*Lactase
*Sucrase

Fruits, vegetables, and other foods have natural digestive enzymes. Eating them can improve digestion process.
Digestive enzymes

 

Chemical and enzymes in small intestine

Small intestine is a long tube, with a small diameter (about 1 inch), extending from pyloric sphincter to the ileocecal valve. Small intestine can be divided into Duodenum, Jejunum, and ileum.

Food moves through it relatively slowly, over a period of hours, allowing time for the actions of digestion and absorption for which this part of the GI tract is designed. The main classes of human digestive enzymes include proteases, lipases and carbohydrases, which respectively break down the macronutrients protein, fats and carbohydrates.

Up to 3L of intestinal juice is secreted daily by cells in the walls of the duodenum, and to a lesser extent the jejunum and ileum.

Pancreatic and intestinal enzymes that finish the digestion of proteins into amino acids. Proteolytic enzymes, including trypsin and chymotrypsin, are secreted by the pancreas. Carboxypeptidase, a pancreatic brush border enzyme, splits one amino acid at a time.

Proteases - break down proteins at optimum pH 7.9-9.7
• Trypsin and chymotrypsin – break down protein polypeptides in dipeptides
• Carboxypolypeptidase – splits peptides into individual amino acids
• Aminopeptidase and dipeptidase free the end amino acid products

Lipids (fats) are degraded into fatty acids and glycerol. Lipases - break down majority of dietary fats at optimum pH 8.0
• Lipase – hydrolyses triglycerides into free fatty acids and 2-monoglyceride, with the present of bile salt.
• Phospholipase – splits the fatty acids of phospholipids
• Esterase – hydrolyses cholesterol esters

All three are serine proteases, but with different cleavage specificities. Their action is complemented by exopeptidases.

Some carbohydrates are degraded into simple sugars, or monosaccharides (e.g., glucose, galactose) and are absorbed by the small intestine. Pancreatic juice supplies a cocktail of enzymes for the digestion of nearly all major nutrients. α-Amylase is secreted in large amounts. This enzyme is different from the salivary α-amylase, which has a slightly different structure (94% amino acid identity) and is encoded by a different gene.

Pancreatic amylase breaks down some carbohydrates (notably starch) into oligosaccharides. Disaccharidases and oligosaccharidases hydrolyze sucrose and lactose, as well as the maltose, maltotriose, and α-limit dextrins that are formed by the action of α-amylase on starch. Other carbohydrates pass undigested into the large intestine, where they are digested by intestinal bacteria.

Carbohydrases - break down carbohydrates at optimum pH 6.7-7.2
• Amylase – breaks down starch, glycogen and other carbohydrates polysaccharides into disaccharides
Chemical and enzymes in small intestine

Small intestines – Main functions

The intestine (bowel) is a winding muscular tube and it extends from the stomach to the anus. Its main purpose is to digest food. The small intestine is longest part of the digestive system where 90% of the digestion and absorption of food occurs, the other 10% taking place in the stomach and large intestine.

The major purpose of the small intestine is digestion and absorption of nutrients. In the small intestine, enzymes (produced by the salivary glands in the mouth, in the pancreas and in the intestinal cells) break down nutrients such as carbohydrates, proteins or fats into their building blocks.

For example, proteins, peptides and amino acids are acted upon by enzymes such as trypsin and chymotrypsin, which are produced by the pancreas. Pancreas also produced lipases and this enzyme break-up triglycerides into free fatty acids and monoglycerides.

The intestinal cells assume the roles of absorbing the building blocks (for example sugar, amino acids or fatty acids) together with vitamins, salts and water which pass into the bloodstream to be used by the body.

The small intestinal cells also produce countless intestinal hormones. These hormones associated and stimulus the production of bile or pancreatic juice. For example, enzymes will enter the small intestine in response to the hormone cholecystokinin, which is produced in response to the presence of nutrients.

The other hormone, secretin activate bicarbonate to be released into the small intestine from the pancreas to neutralize the potentially harmful acid coming from the stomach.
Small intestines – Main functions 

  

Carbohydrate: Process of digestion

Carbohydrates in the diet provide the major exogenous source for glucose, which is the primary energy source for cells.

Carbohydrates are hydrophilic and require a series of reactions to digest them to monosaccharides which are absorbed in the small intestine. Carbohydrates consist of three main groups, simple carbohydrates (monosaccharides), disaccharides and complex carbohydrates (starch, glycogen, and fiber).The common monosaccharides include glucose, fructose, galactose, xylose and ribose.

Starch, the major food polysaccharide, consists of 85% amylopectin and 15% amylose. Amylose is composed of straight chains of glucose molecules linked through1:4-α bond where as amylopectin, in addition to chains of 1:4- α linked glucose molecules, also has 1:6- α links between glucose molecules in adjacent chains forming bridges.

When the person eat carbohydrates, such as a bowl of pasta or some vegetables, the digestive system breaks the carbohydrates down into simple sugars such as glucose, which travel into and through the bloodstream to nourish and energize cell.

The digestion process of polysaccharides such as starch will begin in the mouth where it is hydrolysed by salivary amylase. Chewing, also known as mastication, crumbles the carbohydrate foods into smaller and smaller pieces. The salivary glands in the oral cavity secrete saliva that coats the food particles. Salivary amylase breaks the bonds between the monomeric sugar units of disaccharides, oligosaccharides, and starches. The salivary amylase breaks down amylose and amylopectin into smaller chains of glucose, called dextrins and maltose.

The goal of carbohydrate digestion is to break down all disaccharides and complex carbohydrates into monosaccharides for absorption, although not all are completely absorbed in the small intestine (e.g.,fiber).

Fructose is absorbed by facilitated diffusion while glucose and galactose are actively transported. Glucose, at low concentrations is transported through the mucosal lining into the epithelial cells of the intestine by active transport, via a sodium dependant transporter. The first organ to receive glucose, fructose, and galactose is the liver. The liver takes them up and converts galactose to glucose, breaks fructose into even smaller carbon-containing units, and either stores glucose as glycogen or exports it back to the blood.
Carbohydrate: Process of digestion 

Digestion and absorption of nutrients in human body

The primary functions of gastrointestinal system are ingestion, digestion, absorption of nutrients and excretion of solid waste.

The body requires the consumption of nutrients to support physiological activity.

Proper function of the gastrointestinal system (GI) is essential for normal growth and for maintaining fluid and electrolytes balance.

For the assimilation of nutrients by the body, the bulk of the foodstuffs must first undergo mastication and digestion.

In this process, polymeric substances such as starches, proteins and triglycerides are broken down into their smaller segments “building blocks” of monomeric sugars, amino acids, fatty acids, etc., in preparation for absorption.

With the exception of most vitamins and inorganic substituent, this digestive breakdown process is necessary for absorption into the body.

It is also a factor in body defenses, preventing the potential absorption of “foreign” macromolecules. The GI tract is the largest immune system organ whose primary functions include the digestion and absorption of ingested nutrient and the protection of the body from ingested microorganism and noxious substances.

During digestion/hydrolysis if the polymeric nutrients (especially) the proteins), the vitamins and trace elements associated with them are released, allowing their more efficient absorption.

The large intestine absorbs water and electrolytes from entering content, which happens predominantly in the proximal half and stores fecal matter until defecation, which occurs in the distal half.

Absorption is the process by which the end products of digestion such as monosaccharides, amino acids, glycerol, fatty acid chains, vitamins, minerals and water – pass through the epithelial membranes in the small and large intestine into the blood or lymph system.

The mechanisms for digesting and absorbing major nutrients are fully mature in the premature and term infant.
Digestion and absorption of nutrients in human body

Starch in Human Nutrition

Starch is a widely distributed and abundant constituent of vegetable tissue.

Starch are by far the most significant polysaccharide in the diet. They are are found in grains, legumes and other vegetables and some fruits in minute amounts.

In human nutrition, starch is by far the most significant polysaccharide. It is a relatively large complex compound made up of many coiled or branching chains of single glucose unit.

It yield only glucose in digestion.

After cooking starch is highly digestible by human beings, raw starch often resists digestion.

Many cooks use starch for such diverse properties as thickening gravies and soups, making a sweet pudding or dusting pastry before cooking.

The major food sources of starch include grains in the form of cereal, pasta, crackers, bread and other baked goods.

Starch is used to produce food extenders and sugars syrups such as maltodextrins, glucose, dextrose, fructose, maltose and hydrogenated derivatives.

The extent of starch breakdown within the small intestine varies, depending on the physical form of the food, therefore a substantial amount of the total starch, called ‘resistant starch’ can escape digestion in the small intestine and enter colon.
Starch in Human Nutrition

Digestion and absorption at infant age

Digestion and absorption at infant age
The complex process of digestion/absorption can be optimally effective only when the GI tract and accessory organs are totally develop and fully functioning.

Not only must the muscular tube (alimentary canal) with it a mucosal lining and endocrine cells be operating efficiently in conjunction with the nervous system, but the accessory organs (pancreas, liver, and gallbladder) with their important digestive secretions also must be physiologically mature.

The feeding of infants is based on primarily in degree of maturation of the GI tract and accessory organs.

Good examples of the emphasis on GI tract maturity are the care given to the fat in infant formula and the time and sequence of the introduction of various foods into the infant’s diet.

Only those fats possessing an ease used in commercial formulas and the introduction of solid food, beginning with baby cereal usually occurs no earlier than 4 months of age.

The infant pancreas, although structurally mature at term, is usable for several months to produce enzymes sufficient for effective digestion.

Pancreatic lipase, alpha-amylase and the proteolytic enzymes are in too short supply to accommodate digestion of a mixed diet. Digestion of fat is a real concern because there is a deficiency of bile salts from the liver as well as low lipase release from the pancreas.
Digestion and absorption at infant age

Carbohydrates

Carbohydrates
Unlike proteins, the carbohydrates in the body contribute nothing to the structure of tissue and although they contribute to the regulation of metabolism, they do not control individual molecular events as the enzymes (proteins) do. Their major function is the provision of energy to a variety of tissues, especially to the brain and nervous system which cannot utilize other nutrients for energy.

The carbohydrates in a typical breakfast – toast and tea with milk and sugar – are roughly representative of the distribution of carbohydrate in the average diet: starch from bread, potatoes, rice, pasta: sucrose from sugar: and lactose from milk. Starch is large molecule made up of many glucose units joined together, all glucose units being of similar structure. It is rapidly digested to its basic glucose units which are readily absorbed.

Lactose and sucrose are by contrast very much small molecules, each of which is digested to become effectively (in the liver) two units. The enzymes responsible for their digestion are, respectively, lactase and sucrase. There is rarely a problem is the digestion of sucrose but a great number of number people encounter problems with lactose digestion, most of which are associated with and inadequate supply of lactase.

Undigested lactose passes from small intestine, where digestion and absorption of its glucose units should occur, into the large intestine, where bacteria (a normal non pathogenic population of microbes) ferment the lactose and cause digestive upsets and diarrhea. The bulk of the population of Africa, Southern Europe, and the near East develop lactose intolerance during later childhood and adult life.

Under normal conditions, however the great majority of carbohydrates in our typical meal are digested and absorbed as glucose, if you measured blood glucose levels before such a meal and at half hourly intervals thereafter, you would see a rise in blood glucose, peaking at about the half hour mark and returning to fasting levels almost as quickly. If you were to abstain from carbohydrates for a considerable period say a week, your blood glucose levels would still be normal in spite of a minimal or zero intake, the body’s capacity to maintain blood glucose within specific limits is achieved by a variety of hormones, the two most important of which are insulin and glucagon. Both are secreted by the pancreas into bloodstream, as required.
Carbohydrates