NUTR 1030 1st EditionExam # 2 Study Guide Lectures: 6-13Lecture 6 (February 2)Monosaccharides:Mono= oneSaccharide= sugarMonosaccharide= single sugar that is not broken down further during digestionGlucose: most abundant in diet, but not in monosaccharide form. Also “blood sugar”Fructose: Found in fruits, vegetables and honey and also high fructose corn syrupGalactose: Part of lactose (“milk sugar”)Lactose= galactose + glucoseDisaccharides:Di= twoDisaccharide= two monosaccharides linked by a glycosidic bond- Condensation reaction- BOND types: alpha glycosidic bond, beta glycosidic bondMaltose: (Gluc + Gluc)- alpha bondSucrose: (Gluc + Fruc)- alpha bondLactose: (Galactose + Gluc)- beta bondComplex Carbohydrates:Oligosaccharides:Oligo= fewOligosaccharides= 3 to 10 sugar unitsRaffinose- stachyose- verbocose- Cannot be broken down by digestive enzymes- Found in onions, whole grains and beansPolysaccharides:Poly= manyPolysaccharides= 100s to 1000s of sugar units- Digestibility depends on bond type- Digestible: Starch- glycogen- Indigestible: Dietary fiberDigestible Polysaccharides:Starch (plants): many glucose units linked by alpha bonds- Amylose: straight chain- Amylopectin: branched chainGlycogen (animals): many glucose units linked by alpha bonds- Storage form of glucose in human body- Liver glycogen (90 g): converted to blood glucose- Muscle glycogen (300 g): stored glucose for muscle useIndigestible Polysaccharides:Fiber:- Dietary fiber (occurs naturally in foods) + functional fiber (added to processed foods to provide health benefits)- Soluble fibers: pectin, gum, mucilages and some hemicelluloses- Insoluble fibers: cellulose, hemicelluloses and ligninSoluble vs. Insoluble Fiber:Soluble:- Dissolves in water- Bacteria will digest these, so will yield some energy (1.5-2.5 kcal/g)- Health: can lower blood cholesterolInsoluble:- NOT dissolvable in water- Not metabolized by bacteria- Health: WILL decrease transit timeSimple CHO in Foods:- Natural vs. manufactured- Sweeteners- Nutritivei) Mono and disaccharidesii) High fructose corn syrupiii) Sugar alcohols- Non-nutritiveNon-Nutritive Sweeteners:- Yield no energy- Acceptable daily intake (ADI)- Saccharin (Sweet ‘N Low, pink packet)i) Oldest alternative sweetenerii) Develops bitter taste with cooking- Aspartame (Equal, blue packet)i) Sweetness lost with heating, cannot be used in cookingii) Contains phenylalanine - Sucralose (Splenda, yellow packet)i) Made from sucrose- can be used in cooking- Stevia (Truvia, PureVia)ii) Recently approved by FDA for use in beveragesiii) “Natural” (plant source): sold as dietary supplementLecture 7 (February 4)CHO Recommendations:Our needs are:- Enough for brain and CNS… 45-65% of total energy intake, assuming adequate diet- RDA set to 130g/dShould also get:- <6% as added sugar (about 12 tsp)- 14g fiber/ 1000 kcalI. About 25g/day for females and 38g/day for malesII. Too much fiber (>60 g/day) not recommendedIII. Increases fluid needs, can bind minerals, too satiatingCHO Functions:Digestible CHO- Energy: 4 kcal/gI. Both immediate and stored as glycogenII. Glycogen stores are limited- “Protein Sparing”I. Body does not use amino acids to make glucose if CHO intake is adequate- Prevents ketosisII. Body requires CHO for complete breakdown of fatty acids for energyIndigestible CHO:- Promotes bowl health- prevents constipation and hemorrhoids- Reduces risk of obesity- may promote fullness and satiety- Improves blood glucose control- Reduces cholesterol CHO Digestion:- Begins in the mouthI. Saliva contains enzyme- salivary amylaseII. Starch broken down to dextrins and maltose by salivary amylase- StomachI. Stomach acidity stops the action of salivary amylase- Small IntestineI. CHO in the intestines causes the pancreas to secrete pancreatic amylase= breakdown of polysaccharides to dextrins and disaccharides which stimulate:II. Intestinal cells to release enzymes: maltase, sucrase, and lactaseMaltose + Maltase = glucose + glucoseSucrose + Sucrase = glucose + fructoseLactose + Lactase = glucose + galactoseIII. The monosaccharides can then be absorbedCHO Absorption:- Glucose and GalactoseI. Requires a carrier and energy expenditure- Considered active absorption to absorb these molecules- The energy (ATP) is expended to pump the sodium back out of the cellII. Going against the concentration gradient (low to high)- FructoseI. Absorbed by facilitated diffusion using a carrier - No energy expendedII. Most fructose is metabolized to glucose- All monosaccharides are transported via portal vein to liverTransportation/ Absorption of Monosaccharides:- Portal vein transports absorbed monosaccharides to liver- Liver can:I. Transform fructose and galactose to glucoseII. Release glucose back to the bloodIII. Store glucose as glycogenIV. Transform glucose to store as fat- Insulin (released by pancreas into blood)I. Role in cellular glucose absorptionII. Binds to membrane receptorIII. Stimulates transporter to move to cell membrane- So glucose can be absorbed into cell- Maintenance of blood glucose levelsI. Key roles of liver and pancreasInsulin vs. GlucagonInsulin:- Promotes glycogen synthesis- Increases glucose uptake by the cells- Reduces gluconeogenesis- Net effect: lowers the blood glucoseGlucagon:- Breakdown glycogen- Enhances gluconeogenesis- Net effect: raises blood glucoseGlycemic Index and Load:Glycemic Index:- Ratio of a blood glucose response compared with a standard- Based on a 50 gm carbohydrate servingGlycemic Load:- Amount of carbohydrate in a food multiplied by glycemic index and divided by 100- More accurately reflects blood glucose impactWhat negative effects can a high GL have?- Stimulates the release of insulin- Insulin increases blood triglycerides level- Insulin increases LDL- Insulin increases fat synthesis- Increases risk for CVD- Returns to hunger quickerDietary CHO Related Diseases and Health Concerns:- Dysfunctional CHO metabolism: diabetes mellitus, metabolic syndrome and hypoglycemia- Dietary fiber: diverticulosis and diverticulitis- Lactose: malabsorption/ intolerance- Fructose: malabsorption/ intolerance- Sugar alcohols: GI distressDiabetes Mellitus:- Dysfunctional CHO metabolismType 1 Diabetes Mellitus:- Insulin producing cells in pancreas are destroyed (autoimmune disease)I. Insulin therapy required for life- Diet must be coordinated with insulinI. Exchange system, carbohydrate counting- Increased risk for cardiovascular disease, blindness and kidney diseaseType 2