2 Key Concepts Carbohydrate foods provide energy (calories) Carbohydrates are readily available and usually low costCarbohydrate structures vary from simple to complex to provide both quick and extended energy for the body.What are some of the staple carbohydrates in a diet? Wheat, corn, rice
3 Key Concepts Carbohydrates = Primary fuel source, Major source of ENERGYCarbohydrates – break down rapidlyThe term energy is used interchangeably with calorie, kilocalorie, kcal
5 Carbohydrates Are widely available and easily grown Relatively low in costMay be easily storedApproximately ½ of total calories in American diet come from carbs.
6 CarbohydratesTo produce energy, the body: 1. Digests the carbohydrate (fuel) and changes it to glucose 2. Absorbs and carries this fuel to cells in need 3. Energy is burned and releasedShare these facts with the students:In the typical American diet, half of total caloric intake is in the form of carbohydrates.Daily intake of sugars by Americans accounts for 20% to 40% of total caloric intake.Ask the students what some of the major sources of sugars are in their own diets.
9 Classes of Carbohydrates Monosaccharides – building block of all carbsSimple, single sugarSimple carbohydrateGlucose (also known as dextrose)supply comes from digestion of starchAll sugars convert to glucose in the bloodFructoseFound in fruits, honey – very sweetHigh fructose corn syrup – soda, canned goods, processed foodsGalactoseFrom digestion of milk sugarCHO – CHEMICAL NATURE = CARBON, HYDROGEN, OXYGENMONOSACCHARIDES = BUILDING BLOCKS FOR ALL CARBOHYDRATESABSORBED FROM INTESTINE INTO THE BLOOD STREAM AND STORED IN LIVER AS GLYCOGEN (THIS STORAGE PROVIDESCONSTANT BACKUP SUPPLY OF ENERGY***GLUCOSE = PRIMARY FUEL FOR CELLS, SUPPLY OF GLUCOSE COMES FROM DIGESTION OF STARCH – NOT USUALLY FOUNDIN DIET, EXCEPT CORN SYRUP OR SOME PROCESSED FOODS***FRUCTOSE = FOUND IN FRUITS AND HONEY***HIGH FRUCTOSE CORN SYRUP = INEXPENSIVE, USED MORE OFTEN NOW IN SODAS, CANNED GOODS, PROCESSED FOODS***GALACTOSE = COMES FROM DIGESTION OF MILK, SUGAR OR LACTOSEFigure information:From Mahan LK, Escott-Stump S: Krause’s food, nutrition, & diet therapy, ed 11, Philadelphia, 2004, Saunders.
10 Classes of Carbohydrates, cont’d DisaccharidesDouble sugarSimple carbohydrateSucrose – table sugarPowdered, granulated, brown sugarLactoseSugar found in milkMaltoseNot found in diet, results as a breakdown product of starchUsed as a sweetenerFound in beer, malt products, infant formulaWhich one of these is commonly known as table sugar? SUCROSE – GRANULATED, POWDER, OR BROWN SUGAR***MADE FROM SUGAR CANE OR SUGAR BEETSLACTOSE = SUGAR IN MILK, FORMED IN MAMMARY GLANDS, LESS SWEET THAN SUCROSEMALTOSE = NOT FOUND IN THE DIET, RESULTS AS A BREAKDOWN PRODUCT OF STARCH, SYNTHETICALLY PRODUCED ANDUSED AS A SWEETENERExplain that maltose can be found naturally in foods such as beer but that most often it is an intermediate disaccharide that results from the digestion of starch.Figure information:From Mahan LK, Escott-Stump S: Krause’s food, nutrition, & diet therapy, ed 11, Philadelphia, 2004, Saunders.
11 Classes of Carbohydrates, cont’d Polysaccharides = complex carbsStarchGlycogenDietary fiberPOLYSACCHARIDES = COMPLEX CARBS, MADE UP OF MANY SINGLE-SUGAR UNITs***STARCHES BREAK DOWN SLOWLY IN THE BODY – BROKEN DOWN SOONER THROUGH COOKING/HEATING PROCESSAsk the students to name sources of starch. Grains (cereal, pasta, bread, crackers), legumes (beans, peas), potatoes, rice, cornDoes cooking the starch before eating it make it more digestible? YES
12 Starch Legumes = beans, peas, lentils Most important polysaccharide in the diet- Sources (grains, legumes,potatoes,rice)- Complex CHOLegumes = beans, peas, lentilsEnriched grains are refined grains that have nutrients added back to them (ie: iron, riboflavin, vitamin A)Whole grains – keep outer bran layer, high fiberMOST IMPORTANT DIETARY CHO - WORLDWIDECOMPLEX CHO - STARCHES BREAK DOWN SLOWLY IN THE BODY - BUT ARE BROKEN DOWN SOONER DURING COOKING/HEATING PROCESSSOURCES OF STARCH – GRAINS (CEREAL, PASTA, BREAD, CRACKERS), LEGUMES (PEAS, BEAN), POTATOES, RICE, CORNREMEMBER – 45-65% TOTAL CALS. SHOULD COME FROM CHO – MAJORITY FROM COMPLEX CHO’S – WHOLE GRAINS BEST !!- WHOLE GRAIN – UNREFINED GRAINS – KEEP OUTER BRAN LAYER = FIBER NUTRIENTSName sources of whole grains and mention the marketing done by food manufacturers and stores to promote whole grain consumption.What vitamins and minerals have been added to enriched grains that are normally not found in significant amounts? Iron, calcium, folate
13 Kernel of Wheat Figure information: Kernel of wheat showing bran layers, endosperm, and germ.Courtesy Eileen Draper.
14 Glycogen Not a significant CHO source in the diet Storage form of carbohydrates in the body – for about 24 hours, stored in the liver and muscles.Stored in liver & muscles – it is “recycled”Storage form of quick energyHelps to maintain normal blood sugar throughout day & nightGLYCOGEN IS FOUND IN LIVER/MUSCLE WHERE IT IS RECYCLED - IT IS BROKEN DOWN TO FORM GLUCOSE FOR IMMEDIATE ENERGYGLYCOGEN HELPS TO MAINTAIN A NORMAL BLOOD SUGAR THROUGHOUT DAY & NIGHT (EVEN WHILE ASLEEP, FASTING)WILL LEARN MORE RE: GLYCOGEN CH. 20
15 FiberType of polysaccharideSoluble (helps to lower cholesterol & weight)Beans, oatmeal, barley, broccoli, citrus fruitsInsoluble (provides bulk in GI tract)Stems/leaves of vegetables, bran, whole grainsIndigestible carbohydrate – humans lack enzyme needed to digest fiberImportant for digestion and health of GI tract (gastrointestinal)Fiber is important for health promotion and disease prevention – especially GI, CV, and diabetes managementFIBER DOES NOT HAVE A DIRECT ENERGY VALUE, BUT OTHER DIETARY ASSETS ! (AS ABOVE)SOLUBLE FIBER (WATER SOLUBLE) = BINDS BILE ACIDS AND LOWERS CHOLESTEROL – CERTAIN PLANTS, SEAWEED, FRUITSINSOLUBLE FIBER = IMPORTANT FOR CONSTIPATION – PROVIDES BULK – STEMS/LEAVES OF VEGETABLES, BRAN, WHOLE GRAINNAME DIETARY SOURCES OF FIBER – bran cereals, whole wheat bread, air popped popcorn, black beans, asparagus, cauliflower, green peas,Raisins, apples – see page 20 in book for list of dietary fiber
17 FIBER Recommended daily intake = Men – 38 grams Women – 25 grams Reduced for people over 50 yrs. –Men – 30 gramsWomen – 21 grams
18 Sweeteners Nutritive sweeteners Nonnutritive sweeteners Sugar alcohols (sorbitol, mannitol, xylitol)Have caloric valueNonnutritive sweetenersArtificial sweeteners in food (aspartame, saccharin)Have no caloric valueSWEETENERS = CHO – EITHER NUTRITIVE OR NON-NUTRITIVEDo sugar alcohols provide the same amount of energy as other carbohydrates?Because sugar alcohols are absorbed more slowly from the gut than are other carbohydrates, how would this affect blood glucose levels?Nonnutritive sweeteners are hundreds of times sweeter than table sugar. Explain how adding a minute amount can sweeten a food.
19 Function of Carbohydrates Basic fuel supplyEnergy for physical activities and all work of body cellsReserve fuel supplyProvided by glycogenMaintains normal blood glucose levelCarbohydrates burn in the body at rate of 4 kcal/g.RESERVE FUEL SUPPLY = FROM GLYCOGEN (LIVER,MUSCLE) – NEED TO REFUEL BY EATING CHO REGULARLY – THIS HELPS TO AVOID DRAMATIC CHANGES IN BLOOD GLUCOSE LEVELSOTHERWISE, ENERGY COMES FROM BREAKDOWN OF PROTEIN IN THE MUSCLEExplain this in terms of work: 30 minutes jogging burns approximately 200 calories. How many grams of carbohydrate would be needed to provide that energy? 50 g How many pieces of bread would a person need to eat to get 50 g? 3-4 piecesExplain the process of blood glucose level variance and homeostasis. The body regulates blood glucose to keep all cells provided with energy at all times.
20 Special Tissue Functions of Carbohydrates LiverStores glycogen - to protect cells from depressed metabolic functionBack up energy sourceProtein and fatCarbohydrates protect (regulate) proteins and fat – allows them to be used properly for tissue buildingSpares body protein from being used for energyThe protein-sparing function of carbohydrates protects proteins, allowing them to be used for tissue growth and maintenance.Carbohydrates prevent the rapid breakdown of fats that would produce excess amounts of ketones.What would happen without reserve stores of glycogen? - breakdown of protein (muscle) and fat (tissues), altered blood glucoseWhich is used first to maintain blood glucose levels, liver or muscle glycogen?
21 Special Tissue Functions of Carbohydrates, cont’d HeartGlycogen is vital emergency fuel for heart muscleCentral nervous systemBrain dependent on minute-to-minute supply of glucoseEnhances learning and memoryHEART MUSCLE SUSTAINS LIFE ! FATTY ACIDS ARE MAIN FUEL SUPPLY OF HEART – GLYCOGEN IS EMERGENCY FUELBRAIN HAS NO STORED SUPPLY OF GLUCOSE – NEEDS IT FROM BLOOD SUPPLYLow blood sugar may cause brain damage and death.What type of effects would be seen in someone who cannot regulate blood glucose normally and therefore has low levels for an extended amount of time (e.g., diabetics)?
22 Food Sources of Carbohydrates StarchesProvide important complex carbohydrates, key to a good diet !Important source of fiberSugarsHigh-sugar diets carry health risksAverage American eats 10 tablespoons per day***REVIEW TABLE 2.5 RE: CHO FOODS !EXAMPLES -----CHO CONTENT OF FOODS (GRAMS PER SERVING) – ½ MED. TOMATOE = 2.4 GM, 1/2C. CHEDDAR = .7GM, 1 CUP LETTUCE = 1 G.,*****SUGARS INCLUDE: GLUCOSE, SUCROSE (TABLE), FRUCTOSE, LACTOSE (IN MILK), MALTOSETSP. SUGAR = 4.2 GM, HIGH FRUCTOSE CORN SYRUP = 14.5 GM, 1 C. SKIM MILK = 12 GM., 1 C. PASTA = 39 GM, 1 SLICE WHITE BREAD 12 GM1 OZ. SQUARE BROWNIE = 18GM, SODA (COLA) = 35 GM, 1 PKG. SKITTLES 2OZ = 52 GM, 1 PACKAGE (5 OZ) DRIED FRUIT = 93 GMAVERAGE AMERICAN EATS 10 TABLESPOONS OF ADDED SUGAR PER DAYWhat risks are associated with high-sugar diets?Explain that one of the easiest steps someone dieting can take is to cut sugared drinks from the diet.
23 Food Sources of Carbohydrates 1 slice white bread 12 grams1 cup pasta grams1 cup skim milk 12 grams1 soda (cola) 35 gramsSkittles (2 oz.) 52 gramsDried fruit (5 oz.) 93 grams1 tsp. sugar gramsRDA = grams per day
24 High Fructose Corn Syrup Sweetener – from cornAverage annual intake = 60 lb. per personIncreases triglycerides and body fatLeads to increased cravings
25 SOURCES OF HIGH FRUCTOSE CORN SYRUP: SOURCES OF HIGH FRUCTOSE CORN SYRUP: ***CHECK YOUR KITCHEN FOR 3 ITEMS W/ HCFS - ASSIGNMENTSODA FRUIT FLAVORED DRINKSFAST FOODS SPECIAL K AND MANY CEREALSPROCESSED FOODS CALORIE SNACK PACKSSALAD DRESSINGS ** USED AS SWEETENER AND PRESERVATIVEYOPLAIT YOGURT
26 Body Needs for Carbohydrates Dietary Reference Intakes45% to 60% of adult’s total caloric intake should come from carbohydrate foodsApproximately gm per dayLimit sugar to no more than 25% of calories consumedDietary Guidelines for Americans, 2005General guidelines: fiber rich foods, whole grains, reduced sugar or no-added sugar, non-caloric sweeteners, oral hygieneGUIDELINES ENCOURAGE THE FOLLOWING:CHOOSE FIBER RICH FRUITS, VEGETABLES AND WHOLE GRAINSCHOOSE FOODS WITH LITTLE OR NO ADDED SUGAR – CHOOSE NON-CALORIC SWEETENERSGOOD ORAL HYGIENE TO REDUCE DENTAL CARRIES – LESS SUGAR !!!What does MyPyramid focus on concerning the grains group? Make half your grains whole.What recommendations do the Dietary Guidelines for Americans, make?What recommendations would the students provide to others?