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Nutrition - Chapter 4 Lecture Notes Nutrition - Chapter 4 Lecture Notes Presentation Transcript

  • Chapter 4 Lecture Outline Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display
  • Photosynthesis
  • Monosaccharides
    • Structure
    • Glucose
    • Fructose
    • Galactose
  • Glucose
    • Major monosaccharide in the body
    • Also known as dextrose
    • In bloodstream called blood sugar
    • Breakdown of starches and sucrose
    • Source of fuel for cells
  • Fructose (fruit sugar)
    • In sucrose
    • In fruit, honey, and high-fructose corn syrup
    • Converted into glucose in the liver
  • Galactose
    • In lactose
    • Converted to glucose in the liver
  •  
  • Disaccharides
    • “ Simple sugars”
    • Sucrose (Gluc + Fruc)
      • Sugar
    • Lactose (Galactose + Gluc)
      • Milk products
    • Maltose (Glyc + Gluc)
      • Fermentation
      • Alcohol production
  • Complex Carbohydrates
    • Polysaccharides: Starch & Glycogen
    • Amylose
    • Amylopectin
    • Dietary fiber
  •  
  • Oligosaccharides
    • 3-10 monosaccharides
    • In beans and legumes
    • Not digested
    • Metabolized by bacteria in the large intestine
    • Effect of Beano ®
  • Polysaccharides: Starch
    • 3,000 or more monosaccharides
    • Starch
      • Amylose--straight chain polymer
      • Amylopectin--highly branched polymer
  • Common Starches
  • Glycogen
    • Storage form of carbohydrate for animals and human
    • Structure similar to amylopectin
    • More sites for enzyme action
    • Found in the liver and muscles
  • Dietary Fiber
    • Undigested starch
    • Body cannot break the bonds
    • Insoluble fiber
      • Cellulose, hemicellulose, lignin
      • Not fermented by the bacteria in the colon
    • Soluble fiber
      • Gum, pectin, mucilage
      • Fruit, vegetable, rice bran, psyllium seed
  • Soluble and Insoluble Fiber
  • Benefits of Dietary Fiber
  • Carbohydrates in Foods
  • Sweeteners
  • High-fructose Corn Syrup
    • 55% fructose
    • Cornstarch mixed with acid and enzymes
    • Starch is broken down to glucose
    • Some glucose is converted to fructose
    • Cheaper than sucrose
    • Does not form crystals
  • Other Types of Sweeteners
    • Brown sugar
    • Turbinado sugar (raw sugar)
    • Maple syrup
    • Honey
    • Sugar alcohols (sorbitol, xylitol)
      • ~2.6 kcal/g
      • Absorbed and metabolized slower
      • “ Excess consumption may have a laxative effect”
  • Sugar Substitutes
  • Sugar Alcohols
    • Sorbitol, Xylitol
    • ~2.6 kcals/gram
    • Large quantities can cause diarrhea
    • Do not promote tooth decay
  • Saccharin
    • First produced in 1879
    • 180-200x sweeter than sucrose
    • No potential risk in humans
  • Aspartame (Equal  , NutraSweet  )
    • Composed of phenylalanine, aspartic acid, and methanol
    • 180-200x sweeter than sucrose
    • 4 kcal/gm
    • Not heat stable
    • Complaints of sensitivity
      • Headaches, dizziness, seizures, nausea, etc.
    • Acceptable daily intake: 50 mg per kg body weight (FDA) (~14 cans of diet soda for average adult per day)
    • Warning label for Phenylketonuria (PKU)
  • Sucralose (Splenda  )
    • 600x sweeter than sucrose
    • Substitutes chlorines for hydroxyl groups on sucrose
    • Heat stable
    • Tiny amount digested
    • Excreted in the feces
  • Neotame
    • FDA approved for general-purpose sweetener
    • Similar structure to Aspartame
    • Is not broken down in the body
    • 7,000-13,000x sweeter than sucrose
    • Heat stable
    • Safe for use
  • Acesulfame-K (Sunette  )
    • Approved by FAD
    • 200x sweeter than sucrose
    • Not digested by the body
    • Heat stable
    • Diabetisweet used in baking
  • Tagatose
    • Altered form of fructose
    • 1.5 kcals/gram
    • Does not increase glucose level
    • Does not cause tooth decay
    • Is fermented by large intestine
  • Carbohydrate Digestion
  • Effects of Cooking
    • Softens fibrous tissues
    • Easier to chew and swallow
  • Digestion of Carbohydrate in the Mouth
    • Salivary amylase
      • Breaks starch to shorter saccharides
      • Prolonged chewing
    • Short duration in the mouth
  • Digestion of Carbohydrate in the Stomach
    • Acidic environment
    • No further starch digestion
  • Digestion of Carbohydrate in the Small Intestine
    • Pancreas releases enzymes
      • Pancreatic amylase
    • Absorptive cells release
      • Maltase
      • Sucrase
      • Lactase
    • Monosaccharides are absorbed
  • Carbohydrate Digestion
  • Lactose Maldigestion
    • Reduction in lactase
      • Lactose is undigested and not absorbed
      • Lactose is metabolized by large intestinal bacteria
        • Causes gas, bloating, cramping, discomfort
    • Primary lactose maldigestion
    • Secondary lactose maldigestion
    • Severe cases are called lactose intolerance
  • What To Do if You Have Lactose Maldigestion or Lactose Intolerance
    • Determine amount you can tolerate
    • Eat dairy with fat
    • Cheese & yogurt are usually well tolerated
    • Use Lact-Aid 
  • Absorption
    • Glucose and Galactose
      • Active absorption
      • Energy is expended
    • Fructose
      • Facilitated absorption using a carrier
      • No energy expended
  • After Absorption
    • Portal vein to the liver
    • Liver can:
      • Transform monosaccharide into glucose
      • Release glucose back into the bloodstream
      • Store as glycogen (or fat)
  • Undigested Carbohydrates
    • Only a minor amount escapes digestion
    • Travels to the colon
    • Fermentation by the bacteria
    • Acids and gases produced are absorbed
    • May promote health of the colon
  • Functions of Carbohydrate
    • Supplies energy
    • Protein sparing
    • Prevents ketosis
    • Sweetener
  • Regulation of Blood Glucose
    • Hyperglycemia
    • Hypoglycemia
  • Blood Glucose Control
    • Role of the liver
      • Regulates glucose that enters bloodstream
    • Role of the pancreas
      • Release of insulin
      • Release of glucagon
  • Functions of Insulin
    • Promotes glycogen synthesis
    • Increases glucose uptake by the cells
    • Reduces gluconeogenesis
    • Net effect: lowers blood glucose
  • Functions of Glucagon
    • Breakdown glycogen
    • Enhances gluconeogenesis
    • Net effect: raises blood glucose
  • Epinephrine / Norepinephrine
    • “Fight or flight” response
    • Breakdown glycogen
    • Raises blood glucose
  • Regulation of Blood Glucose
  • Glycemic Response
    • Glycemic Index
      • Ratio of blood glucose response to a given food
    • Glycemic Load
      • Grams of carbohydrate in a food multiplied by the glycemic index of that food
      • Divide result by 100
  • High Glycemic Load
    • Large release of insulin
      • Increase blood triglycerides level
      • Increase Low Density Lipoprotein (LDL)
      • Increase fat deposits
      • Increase clotting
      • Increase fat synthesis
      • Rapid return of hunger
    • Insulin resistance develops (Type 2 diabetes)
  • Dietary Fiber and Health
  • Hemorrhoids
    • Swelling of a large vein
    • Result from excessive straining
  • Diverticula
  • Weight Control and Fiber
    • Filling
    • Low in kcal
    • Satisfied after eating
  • Colon Cancer and Fiber
    • Controversial
    • Focus on fruits, vegetables, beans, and whole grains
    • Higher-fiber foods are more nutrient dense
  • Glucose Absorption and Fiber
    • Soluble fiber slows glucose absorption
    • Better blood glucose regulation
  • Cholesterol and (Soluble) Fiber
    • Absorption of cholesterol inhibited
    • Bile acid absorption reduced
    • Risk for cardiovascular disease and gallstones reduced
    • Insulin release decreased
      • Decrease cholesterol synthesis in the liver
    • Blood cholesterol lowered
  • Carbohydrate Needs
    • RDA is 130 grams/day for adults
    • Average U.S. intake is 180-330 grams
    • Recommendations vary
      • FNB: 45%-65% of total calories
      • Nutrition Facts panel: 60%
    • Focus on fruits, vegetables, whole grains
  • Recommended Dietary Fiber Intake
    • AI is 25 grams/day for women
    • AI is 38 grams/day for men
    • (Goal of 14 grams/1000 kcal)
    • DV is 25 grams for 2000 kcal diet
    • Average U.S. intake:
      • 14 grams/day for women
      • 17 grams/day for men
  • Too Much Fiber
    • > 60 grams/day
    • Extra fluid needed
    • May decrease availability of some minerals
    • Unmet energy needs in children
  • Recommendation for Simple Sugar Intake
    • Low nutrient density
    • Dental caries
    • Added to food and beverages
    • < 10% of total kcal/day with a maximum of 50 grams (12 tsp) per day--WHO
    • Average U.S. intake: 16% of total kcal/day
      • ~82 grams per day
  • Diabetes
    • Type 1 Diabetes
    • Type 2 Diabetes
    • Gestational Diabetes
  •  
  •  
  • Type 1 Diabetes
    • Occurs often in children
    • Genetic link
    • Body stops producing insulin
    • Treatment
      • Insulin Therapy
      • Diet Therapy
  • Type II Diabetes
    • Generally in people > 40 years of age
    • Increasing rates in younger individuals
    • Obesity
    • Treatment
      • Weight loss
      • Oral medications
      • Diet therapy
      • Insulin
  • Hypoglycemia
    • Reactive hypoglycemia
      • Occurs 2-4 hours after eating a meal
      • Possibly due to over-secretion of insulin
    • Fasting hypoglycemia
      • Usually caused by pancreatic cancer
      • Leads to overproduction of insulin
  • Metabolic Syndrome (Syndrome X)
    • 25% of adults have it
    • High blood triglycerides
    • Poor blood glucose regulation
    • Hypertension
    • Risk factors
      • Obesity
      • Lack of physical activities
      • High simple/refined sugar intake
      • Low fiber intake