1. Carbohydrates

2. Carbohydrates  Most easily metabolized nutrient for the body, converted into glucose  glucose provides energy for the brain and ½ of energy for muscles and tissues  glycogen is stored glucose  glucose is immediate energy  glycogen is reserve energy

3. Carbohydrates  Compounds composed of carbon, oxygen and hydrogen that are arranged to make different variations of sugar molecules  all plant food  milk  carbohydrates are not equal –simple carbohydrates –complex carbohydrates

4. Simple Carbohydrates  sugars –monosaccharides – single sugars –disaccharides – 2 monosaccharides

5. Complex Carbohydrates  starches and fibers  polysaccharides –chains of monosaccharides

6. Simple Carbs  Monosaccharides  Mono = one  Saccharides = sugar –glucose, fructose, galactose

7. Glucose  mild sweet flavor  known as blood sugar  essential energy source  found in every disaccharide and polysaccharide  in starchy foods

8. Fructose  sweetest sugar  found in fruits and honey  added to soft drinks, cereals, deserts

9. Galactose  hardly tastes sweet  rarely found naturally as a single sugar  one of the sugars in milk

10. Disaccharides  pairs of the monosaccharides (di = two) –maltose, sucrose, lactose

11. Maltose  2 glucose units  known as malt sugar  not abundant in foods

12. Sucrose  fructose and glucose  tastes sweet –fruit, vegetables, grains  table sugar is refined sugarcane and sugar beets  brown, white, powdered

13. Lactose  glucose and galactose  main carbohydrate in milk, depending on milk's fat content lactose contributes 30- 50% of milk's energy –known as milk sugar

14. Complex Carbohydrates  polysaccharides –glycogen and starch  built entirely of glucose –fiber  variety of monosaccharides and other carbohydrate derivatives

15. Glycogen  limited in meat and not found in plants –not an important dietary source of carbohydrate  BUT –all glucose is stored as glycogen

16. Starches  stored in plant cells (grains, vegetables, potatoes and legumes)

17. Fiber  structural parts of plants –found in all plant derived food  bonds of fibers cannot be broken down during the digestive process –minimal or no energy available

18. Fiber Characteristics  soluble fibers (dissolves in water) –easily digested by bacteria in colon –associated with protection against heart disease and diabetes  lower cholesterol and glucose levels –found in legumes and fruits

19. Fiber  insoluble (does not dissolve in water) –promote bowel movements –alleviate constipation –found in grains and vegetables –associated with reduced cancer rates

20. Meeting Fibre Needs  Choose whole grain more than refined products such as white bread  Males aged 14 to 50 need 38g of fibre daily  Females aged 14 to 18 need 36g of fibre daily (decreased to 25g at age 19)

21. Carbohydrate Digestion  break down into glucose –body is able to absorb and use  large starch molecules – extensive breakdown  disaccharides –broken once  monosaccharides –don’t need to be broken down

22. Carbohydrate Digestion  begins in mouth –chewing releases saliva –enzyme amylase hydrolyzes starch to polysaccharides and maltose  stomach –no enzymes available to break down starch –acid does some breakdown –fibers in starch provide feeling of fullness

23.  small intestine –majority of carbohydrate digestion takes place here –pancreatic amylase reduces carbs to glucose chains or disaccharides –specific enzymes finish the job  maltase –maltose into 2 glucose  sucrase –sucrose into glucose and fructose  lactase –lactose into glucose and galactose

24.  large intestine –1-4 hours for sugars and starches to be digested –only fibers remain  attract water, which softens stool

25. Carbohydrate Absorption  glucose can be absorbed in the mouth  majority absorbed in small intestine

26. Lactose Intolerance  more lactose is consumed than can be digested –lactose molecules attract water  cause floating, abdominal discomfort, diarrhea –intestinal bacteria feed on undigested lactose  produce acid and gas

27. Lactose Intolerance  management requires dietary change –6 grams (1/2 cup) usually tolerable –take in gradually –enzyme drops or tablets  lactose free diet is extremely difficult to accomplish

29. Imbalance  diabetes –after food intake, blood glucose rises and is not regulated because insulin is inadequate  hypoglycemia –blood glucose drops dramatically  too much insulin, activity, inadequate food intake, illness  diet adjustment includes fiber-rich carbs and protein

30. Maintaining Blood Glucose Homeostasis Intestine When a person eats, blood glucose rises. 1 2 Insulin stimulates the uptake of glucose into cells and storage as glycogen in the liver and muscles. Insulin also stimulates the conversion of excess glucose into fat for storage. 3 4 5 6 7 Blood glucose begins to rise. a The stress hormone epinephrine and other hormones also bring glucose out of storage. Glucose Insulin Glucagon Glycogen Glucagon stimulates liver cells to break down glycogen and release glucose into the blood. a Liver Low blood glucose stimulates the pancreas to release glucagon into the bloodstream. As the body's cells use glucose, blood levels decline. Glucagon Pancreas Fat cell Liver Muscle High blood glucose stimulates the pancreas to release insulin. Pancreas Insulin

31. Sugar  ½ comes from natural sources, ½ from refined and added –sucrose, corn syrup, honey  excess can lead to nutrient deficiencies and tooth decay –empty calories –sugar and starch break down in the mouth

32. Sugar  recommended intake –added sugar = no more than 10% of energy intake