3.1 carbohydrate
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This chapter discusses macronutrients, focusing on carbohydrates. It defines carbohydrates and their subcategories, including monosaccharides like glucose, fructose, and galactose; disaccharides like maltose, sucrose, and lactose; and polysaccharides like starch, glycogen, and fiber. It also covers carbohydrate digestion and metabolism, recommended daily intake, and related diseases such as lactose intolerance and diabetes.
3.1 carbohydrate
- 1. FST 307 BASIC NUTRITION CHAPTER 3 MACRONUTRIENTS
- 2. CHAPTER OUTCOMES At the end of this chapter, students should be able to:- a) Explain briefly about classification, function, digestion of carbohydrate b) Describe recommeded intake and related diseases for carbohydrate
- 4. Carbohydrates are primary fuel source for certain cells such as nervous system, red blood cells and brain cells. 1 gram of carbohydrates yields about 4kcal of energy We obtain about 50% - 60% of our energy intake from carbohydrates (maybe higher % in the developing world)
- 5. COMPOSITION Composed of carbon, hydrogen, oxygen in the ratio 1:2:1 respectively: (CH2O) Plants use CO2, H2O and energy (from the sun) to produce the CH2O we eat. The process is called photosynthesis
- 7. MONOSACCHARIDE Also known as simple carbohydrates / simple sugars Consist of 3 monosaccharide (single sugar) such as: a) Glucose b) Fructose c) Galactose
- 8. 1. GLUCOSE Major monosaccharides in body Also known as dextrose and blood sugar Essential energy source for all body activities Glucose in the body exist in ring form
- 9. 2. FRUCTOSE Major monosaccharides in diet Also known as levulose Sweetest among the sugars Same chemical formula with glucose but different structure Arrangement of the atoms stimulates the taste buds Abundant in fruit, honey, corn syrup Used in the production of soft drinks, confectionaries, frozen foods
- 10. 3. GALACTOSE Not found free in nature Always combines with glucose to form lactose Available in milk and dairy products
- 11. DISACCHARIDE Double sugars formed by chemical bonding of two monosaccharide 2 types of bonding: a) alpha glycosidic bond: can be digested by human intestinal enzymes b) beta glycosidic bond: cannot be digested by human intestinal enzymes 3 types of disaccharides a) Maltose = glucose + glucose b) Sucrose = glucose + fructose c) Lactose = glucose + galactose
- 12. CONDENSATION
- 13. HYDROLYSIS
- 14. 1. MALTOSE Mixture of: Glucose + Glucose Link by alpha glycosidic bond Situation where starch breakdown into maltose: a) CH2O digestion b) Fermentation process -> alcohol Source: Grains
- 15. 2. SUCROSE Mixture of: Glucose + Fructose Link by alpha glycosidic bond Also known as table sugar Sucrose refine from juice of sugarcane or sugar beet Sources: from plant only – honey, maple syrup, sugarcane
- 16. 3. LACTOSE Mixture of: Glucose + Galactose Link by Beta glycosidic bond Also known as milk sugar Source: milk, milk products
- 17. POLYSACCHARIDE Also known as complex carbohydrate Mainly consist of: a) Starch b) Glycogen c) Fibers (indigestible polysaccharide)
- 18. 1. STARCH Storage form of energy in plants Long, branch (amylopectin) and unbranch (amylose) chain of glucose molecules All starchy food derives from plant Source: rice, corn, barley, oats, legumes and tubers
- 19. 2. GLYCOGEN Storage form of energy in animal body – temporary storage in muscle and liver Glucose molecules in glycogen structure linked in highly branched chains that permits rapid hydrolysis More branches – more sites for enzyme reaction quickly broken down when needed Limited sources in food because animal muscles rapidly hydrolyze after slaughter
- 20. 3. FIBERS (INDIGESTABLE POLYSACCHARIDES) Provide structure in stem, trunks, roots, leaves and skin of plants Polysaccharide cannot be broken down by digestive enzyme a) Lignin – woody parts in carrot, seeds in strawberry b) Cellulose – primary constituents of plant cell wall c) Hemicelluloses – main constituents of cereal fibers d) Pectin – commonly found in vegetables and fruits, forms gel in water, control texture and consistency, thicken jelly e) Gums – used as additives f) Mucilage – used as stabilisers
- 22. 1. Yielding energy 2. Sparing protein from use as an energy source 3. Preventing ketosis (pronounce : kitousis) 4. Imparting flavor and sweetness to foods 5. Maintaining health of large intestine
- 28. HOW BODY MAINTAIN BLOOD GLUCOSE LEVEL
- 29. Storing glucose as glycogen a) Muscle glycogen – fuel muscle activity b) Liver glycogen – to maintain blood glucose c) Glycogen can be quickly release for energy as needed d) Glycogen will last from a few hours to one day depending on activity level Using glucose for energy a) primary fuel for brain, RBC, nervous system, fetus and placenta b) Need to metabolize fat completely c) Glucose in blood used by body cell (undergo metabolic reaction) - produce energy
- 30. HORMONES RELEASE FROM PANCREASE Insulin a) Produced by beta cell in pancreas b) Functions during the rising glucose level in blood after a meal i. Promote the storage of glucose as glycogen in liver and muscle ii. Stimulate protein synthesis and increase lipid synthesis iii. Remove glucose from the blood so decreasing blood glucose levels to the normal stage Glucagon a) Made in alpha cell in pancreas b) Stimulates the breakdown of liver glycogen so glucose were released to the bloodstream c) It also help restore blood glucose to normal concentration
- 31. BLOOD GLUCOSE LEVEL Normal condition Blood glucose level is about 70 – 110mg/dl (<6.1 mmol/l ) Hyperglycemia Blood glucose level is exceeds 170mg/dl (>7 mmol/l ) Having high blood glucose Begin to spill over into the urine Hypoglycemia Blood glucose level falls below 40 – 50mg/dl (<4 mmol/l ) Having low blood glucose Symptom: nervous, hungry, headache
- 33. RECOMMENDED INTAKE OF CARBOHYDRATE No Recommended Daily Allowance (RDA) Recommended nutriens intake (RNI) a) Total CHO: 55 – 70% of daily calories b) Sugars: <10% of total energy c) Dietary fibre: 20-30g per day 2000kcal = daily CHO intake ~ 275 to 300g
- 34. SOURCE OF CARBOHYDRATE Sugar, honey, jam, jellies, fruits, baked potato: greatest % of kcal from CHO Rice, bread, corn flakes, noodles: 75% of kcal/energy as CHO Peas, broccoli, oatmeal, dry beans, legumes, fries, skim milk: moderate Chocolate, whole milk: 30% - 40% of kcal as CHO (more fat) Essentially no CHO: beef, chicken, fish, vegetable oil, butter, margarine.
- 36. LACTOSE INTOLERANCE A condition that results from inability to digest the milk sugar lactose. It can normally occur when (to normal people):- a) Large amount of lactose is consumed more than the available lactase can handle b) Lactose molecule remain in the intestine undigested c) Undigested lactose becomes food for intestinal bacteria d) Bacteria multiply and produce irritating acid and gas e) It cause bloating, abdominal discomfort and diarrhea.
- 37. Natural causes: a) Lactase activity commonly declines with age b) Lactase deficiency may also develop when the intestinal villi are damaged by disease, certain medicine, prolonged diarrhea or malnutrition. c) Lactose malabsorption may be temporary or permanent. d) An infant is born with a lactase deficiency
- 38. Overcome lactose intolerance: a) Remove all milk products from the diet – but it can lead to nutrient deficiencies (calcium, vitamin D and riboflavin). b) Read labels and avoid foods that include milk, milk solid, whey (milk liquid) and casein (milk protein). c) Need to check all medications - because 20 percent of prescription drugs contain lactose as a filler d) Increase intake of milk product gradually e) Consume fermented milk products such as yogurt f) Consume commercially prepared milk products that have been treated with an enzyme that breaks down the lactose.
- 39. DIABETES Definition: a) A metabolic disorder characterized by:- i. Elevated blood glucose ii. Altered energy metabolism b) It is caused by:- i. Defective insulin action ii. Defective insulin secretion iii. Both combination
- 40. Types of diabetes a) Type 1 i. Failure of insulin production ii. Dependent on insulin injection because insulin not produce by pancreas iii. Usually happen to children and adolescent b) Type 2 i. Not dependent on insulin injection ii. Insufficient/inactivate insulin produced by the pancreas iii. Usually happens to people 40 years and above, heredity and obese is the main contributor
- 41. PAUSE TO PONDER… a) Please explain briefly about classification, function, digestion of carbohydrate b) Try to describe recommeded intake and related diseases for carbohydrate
- 42. END OF CHAPTER 3.1 CARBOHYDRATE
Editor's Notes
- #29: HOW BODY MAINTAIN BLOOD GLUCOSE LEVEL