Digestion, Absorption and Metabolism of Carbohydrate

1. Digestion, Absorption and Metabolism of Carbohydrate Dr. Ir. Jamhari, M.Agr.Sc., IPM,

2. Digestion in mouth • Digestion of carbohydrates are physically carried by the tooth through the masticatory function zoomed particles. • Mouth salivary glands secrete fluids that cause food particles become wet and fluffy. • Amylase of salivary gland hydrolyzes polysaccharide starch into simple and maltose.

3. Digestion in Oesophagus • Food particles swell, because of the fluid from the salivary glands. • Hydrolysis of starch into maltose saccharide simple and continues into the esophagus.

4. Digestion in stomach • Amylase of the salivary glands become active in the time of entry into the stomach, because the stomach is acidic. • Gastric acid and gastric enzymes digesting enzyme saliva. • Stomach acid also hydrolyze maltose and sucrose.

5. Digestion in intestinum • The pancreas secretes pancreatic amylase and secreted in the duodenum. • Pancreatic amylase hydrolyzes polysaccharide into maltose and glucose. • Some disaccharide also digested in the small intestine, among others, lactose, and sucrose. • High fiber foods will decrease the rate of absorption of carbohydrates and fats. • Fiber can also bind to the mineral thus decreasing the absorption of minerals.

6. Digestion in colon • Most fiber directly into the large intestine. • Bacteria enzymes hydrolyze fibers into glucose. • Fiber binds water, regulate bowel movement, bind cholesterol and some minerals and bring it to the outside of the body.

7. Digestion of Fiber • Mechanical digestion in the mouth and with saliva fluid so that the fibers swell. • Digestion does not occur in the esophagus, stomach and small intestine of the fiber. • Chemical fiber digestion occurs in the large intestine by the enzyme produced by the microbe to produce water, gas, and fatty acids.

8. Absorption into the Bloodstream • Most is absorbed in the small intestine but a small amount can be absorbed in the mouth. • Monosaccharides are absorbed by active transport through the walls of the small intestine. • Circulated in the blood and converted mainly into glucose by the liver for energy • Converted into glycogen and stored if energy is not needed.

9. Glucosa Absorption

10. Transport Mechanism

11. Carbohydrate Transportation • The final result of the digestion of carbohydrates in the form of glucose is transported into the cell as a source of energy, while fructose and galactose is transported directly into the liver for conversion into glucose. • If the high blood glucose levels on the insulin will stimulate change glucose into glycogen and stored in the liver or in the muscles, thus preventing hyperglycemia. • If blood glucose levels are low, the hormones glucagon will stimulate the process of solving glycogen into glucose, thus preventing hypoglycemia.

12. Carbohydrate metabolism • Anabolism are reactions in which small molecules are put together to build larger ones. Anabolic reactions consume energy and often involve reduction. • Catabolism are reactions in which large molecules are broken down to small ones. Catabolic reactions release energy and often involve oxidation. • Carbohydrate metabolism is a biochemical process that includes the formation, breakdown, and inter convertion carbohydrates in living things. • Glucose and other carbohydrates are part of the metabolism and photosynthesis in plants that can be used as an energy source of cellular respiration.

13. Formation of Energy from Glucose • Breakdown of glucose into acetyl CoA. Glucose is broken down into two molecules pyruvate (3C). Pyruvate releasing carbon and binding CoA into acetyl CoA. • Solving acetyl CoA through tricarbolyc acid cycle (TCA) cycle or Krebs. • Excessive consumption of carbohydrates are broken down into pyruvate and acetyl CoA, then stored as fat. • Energy derived from carbohydrates is stored in the form of ATP. • Aerobic respiration of glucose and oxygen to produce energy as well as carbon dioxide and water as by-products. • 1 g carbohydrate oxidation can produce 4 kcal of energy.

14. Metabolism Glucose Anaerobic • Glucose breakdown takes place in muscle without oxygen, until pyruvate has been produced. • Pyruvates are converted into lactic acid and release into blood. • Liver converts lactic acid into glucose and it can be used again (Cori cycle).

15. Cori Cycle

16. Carbohydrate can be used • For energy • For glycogen storage • For amino acid synthesis • For fat storage

17. Metabolic Pathways • Glycolysis is solving process glucose into ATP and Pyruvate. • Glycogenesis is the process of formation of glycogen from glucose .. • Glycogenolysis is glycogen into glucose-solving process. • Gluconeogenesis is the process of glucose or glycogen formation of simple organic compounds.

18. Glycolysis • Aerobic glycolysis produces pyruvate. • Pyruvate oxidized to produce acetyl CoA. • Acetyl CoA enter Kreb Cycle produces CO2, H2O and ATP • Anaerobic glycolysis produces lactate.

19. Cori cycle • Anaerobic glycolysis in muscle will produce lactate. • Lactate was released from skeletal muscle when exercise or move. • Lactate is transported to the liver and converted back into pyruvate by lactate dehydrogenase. • Pyruvate then converted again into glucose by gluconeogenesis.

20. Glycogenesis • Glycogen synthase catalyzes the formation of binding α-1,4-glucosidic on glycogen. • Enzyme catalyzes the formation of bonds α-1,6-glucosidic on glycogen. • Each branch polymerized with α-1,4 bond-glucosidic.

21. Glycogenolysis • Glycogenolysis is the breakdown of glycogen into glucose. • Glycogenolysis is stimulated hormones glucagon and epinephrine.

22. Glycogenolysis • Catalyzes the breakdown of glycogen phosphorilase bond α (1 → 4) glicosidic produce glucose 1-phosphate. • Branch breaking bonds digesting enzyme α (1 → 6) on glycogen branch. • Glucose 1-phosphate is converted into 6-phosphate glucose by phosphogluco mutase. • Glucose 6-phosphate is converted to glucose by glucose-6-phosphatase. • Glycogenolysis takes place in the liver and produces glucose to be transported into the blood vessels to increase blood glucose concentrations. • Glucose is up in the muscles is converted into glucose 6-phosphate to glycolysis process.

23. Gluconeogenesis • Gluconeogensis is the process of formation of glycogen or glucose from compounds of non-sugar, such as pyruvate, lactate, glycerol, and amino acids (alanine and glutamine). • Gluconeogenesis takes place in the liver and kidney cortex. • Gluconeogenesis occurs during fasting and intensive exercise.

24. Gluconeogenesis from pyruvate • Pyruvate the formation oxaloacetate from pyruvate carboxylase. • Oxaloacetate is then converted into phosphoenolpyruvate carboxykinase by phospho enolpyruvate. • Fructose-1,6-biphosphatase converts fructose-1,6-biphosphate into fructose-6-phosphate. • Formation of glucose-6-phosphate from fructose-6-phosphate by phosphoglucose isomerase • Glucose-6-phosphate is hydrolyzed by glucose-6-phosphatase to produce glucose.

25. Substrate for gluconeogenesis • Lactic acid from muscles • Glycerol from hydrolysis of triglycerides • Glucogenic of amino acids • Propional acid in ruminants

26. High blood glucose concentration • High blood glucose concentration stimulates the pancreas to release insulin into the bloodstream. Insulin will stimulate glycogenosis and store glycogen in the liver or muscles. • The liver also can convert glucose into fat and store in depots of fat.

27. Low blood glucose concentrations • Low blood glucose concentration stimulates the pancreas to release the hormone glucagon into the bloodstream. Glucagon stimulates the liver or muscles to degrade glycogen into glucose through a process of glycogenolysis. Glucose is transported into the blood vessel to blood glucose concentration.

28. Concentration of blood sugar-regulating hormone • Insulin is a hormone that is secreted by the beta cells of the pancreas to respond to the concentrations of blood sugar is higher than normal (hyperglycemia). • Glucagon is a hormone produced by the alpha cells of the pancreas to respond to the concentration of blood sugar is lower than normal (hypoglycemia).

29. Carbohydrate Metabolism Diseases • Diabetes mellitus • Lactose intolerance • Fructose intolerance • Galactosemia • Glycogen storage disease

30. Diabetes Mellitus • Diabetes mellitus is a metabolic disorder characterized by hyperglycemia (high blood sugar) and other signs, as distinct from a single disease or condition.

31. Diabetes Mellitus Types • Type 1 is caused due to pancreatic beta cells are unable to produce insulin at all. • Type 2 is caused due to damage to the beta cells produce insulin and therefore can not be optimal because of the aging process, or the wrong diet. • Gestational diabetes is similar to type 2 but genetically caused by the hormones of pregnancy.

32. Causes of Diabetes Mellitus • The genetic defect in beta cells (autosomal or mitochondrial). • Deposition of abnormal fat. • Diseases of the pancreas (eg chronic pancreatitis, cystic fibrosis). • Hormonal disorders. • Chemicals and drugs.

33. Characteristics of Diabetes Mellitus • Fasting blood glucose level greater than or equal dengan126 mg / dL (7.0 mmol / L). • Blood glucose level greater than or equal to 200 mg / dL (11.1 mmol / L) after two hours of consuming 75 g of glucose. • Blood glucose level greater than or equal to 200 mg / dL (11.1 mmol / L) when measured at random.

34. Treatment and Management • Education, diet, exercise, glucose monitoring. • Changes in lifestyle, to control blood pressure and cholesterol through more exercise, quitting smoking, consuming a proper diet, and eat the appropriate medication.

35. Lactose Intolerance • Lactose intolerance is a condition in which the lactose can not be metabolized due to the lack of lactase. • Lactose intolerance can sometimes be confused with milk allergy, the former is a lack of the enzyme lactase, the latter is an autoimmune reaction (usually) to milk proteins.

36. Managing Lactose Intolerance • Adjustment body with dairy products. • Reduce lactose in dairy products, diversification of dairy products. • Treatment with lactase enzyme

37. Evaluation of Biological Value Carbohydrates • Foodstuffs referred to has nutritional value when a high carbohydrate can be absorbed and used as energy source for cells of the body. • A food that has a low carbohydrate nutritional value, which is due can not be absorbed by the body, does not necessarily mean having a low biological value. • Dietary fiber is a carbohydrate that can not be absorbed by the body, but has biological benefits in terms of lowering blood cholesterol levels (hypocholesterolemic) or hold the rate of increase in blood sugar (hypoglycemia).

38. Evaluation of Biological Value Carbohydrates • Biological value is relative to each individual, depending on their physiological condition. • The rice has a low glycemic index have a high biological value for diabetics, but for children or sportsmen requiring high energy that rice has a low biological value.

39. Classification of carbohydrates • Long chain carbohydrates that classification is based on short length of chain, consisting of monosaccharides (simple sugars), oligosaccharides (short chain), and polysaccharides (long chain). • Glycemic and non-glycemic carbohydrates that classification is based on whether or not a digestible carbohydrates to produce glucose in the small intestine. • Fermentable or can not be fermented is non-glycemic carbohydrates classification based fermentable and which can not be fermented by bacteria in the large intestine (colon).

40. Classification of carbohydrates • Glycemic carbohydrates has a function as a source of energy (calories) to the body. • Non glycemic carbohydrates although not result in significant energy, but contribute in the prevention of several degenerative diseases. • The biological value of carbohydrates is influenced by the presence of compounds antiamilase present in foodstuffs. At nuts antiamilase compounds such as proteins, whereas in the form of compounds sago tannin

41. Oligosaccharide • Oligosaccharides consisting of 2 to 10 saccharide units. • Indigestible oligosaccharides containing bond-galactoglucose beta and beta-galacto-galactose, and is found in many nuts. • These oligosaccharides undergo fermentation in the colon and cause a buildup of gas in the digestive tract. • How to reduce the levels of oligosaccharides, namely by soaking the nuts followed by germination or fermentation.

42. Oligosaccharide • The process then beta-galactoside bond cleaved by beta-galactosidase enzyme, which is present endogenously in the food ingredients or produced by microbes.

43. Sugar alcohol • Sugar alcohol is a monosaccharide or disaccharide which has many hydroxyl groups. • The sugar alcohol derived from hydrogenation of mono-disaccharide products, for example sorbitol from glucose, maltitol of maltose. • Sugar alcohol sweetener was developed as a substitute for sucrose, but have a good effect, especially for dental health and prevent obesity because it has a low glycemic index.

44. Physiological Functions Oligosaccharides and Sugar Alcohols • Produce low energy • Had no effect on insulin secretion of the pancreas • Fixing microflora intestine (prebiotic potential) • Protecting dental caries

45. Kinds of sugar alcohols • Can not be digested (eg oligosaccharides and the disaccharide alcohol), • Can be absorbed but not metabolized (e.g. monosaccharides erythritol), • Only a few can be absorbed but can be metabolized (monosaccharides example sorbitol and mannitol).

46. Prebiotics • Oligosaccharides that can not be digested or monosaccharide that can not be absorbed by the small intestine can be used by the bacteria of the intestine (mainly located in the large intestine), consequently produced a number of SCFA (short chain fatty acids) that cause the pH of the lumen of the large intestine decreases, so that the beneficial bacteria (Bifidobacterium and Lactobacillus) increased (acid resistant), while the number of harmful microbes (Clostridium) decreases as it is sensitive to acid.

47. Probiotics • Bacteria that live in the gastrointestinal tract and provide health benefits called probiotics, while the carbohydrate group that became the 'food' (fermentable) probiotic called a prebiotic.

48. Non-cariogenic sweetener • Digestible oligosaccharides (normal energy), for example: coupling sugar, palatinosa. These sweeteners increase blood sugar levels and stimulate the secretion of insulin. • Mono- or oligosaccharides which produce lower energy (not digested or absorbed slightly): neosugar, sorbitol, erythritol, maltitol, lactitol and palatinit.

49. Fiber foods • Dietary fiber is a polysaccharide hydrolysis-resistant crops digestive enzymes. • Crude fiber is part of the food that can not be hydrolyzed by dilute sulfuric acid-heat (H2SO4 1:25%) and aqueous sodium hydroxide-heat (NaOH 1:25%). • Based on the solubility, dietary fiber is divided into two groups, the SDF (soluble dietary fiber) and IDF (insoluble dietary fiber). • SDF can be fermented by intestinal bacteria to produce hydrogen gas, methane and CO2, as well as the SCFA.

50. Fiber foods • Wide SCFA produced: formic, acetic, butyric acid, propionic acid. • SCFA important for intestinal health because it is the main energy source for cells of the colon, have an effect on reduction in blood cholesterol levels, as well as other functions.