Carbohydrates in human nutrition

Carbohydrates in human nutritionThe origin of dietary carbohydratesCarbohydrate rich food come almost exclusively from plantsMilk is the only animal deravative that contains sygnificant amount of carbohydratesCarbohydrates..Polyhydroxy aldehydes, ketones, alcohols, acids, their simple deravatives and their polymers having linkages of the acetal typeFirst link in the food chainPhotosynthesis plants store some of suns energy (0.1%) in chemical bonds of CHOCO2 + H2O CHOAll plant food have CHOOnly significant animal food to have Cho is milkEnergy source for man 8% eskimos; >70% some 3rd world countriesCHO functionsEnergy all cells useSome cells (RBC, brain) can use only CHO until starvation sets inNeed for effective burning of fatSpares protein from use for energyFiber - alternative form of CHO, provides a number of benefitsCarbohydratesCarbohydrates meets your body energy needsFeed your brain and nervous systemKeep your digestive system fitWithin calorie limits, help keep your body leanTogether with fats and protein, digestible carbohydrates add bulk to foodIndigestible carbohydrates yield little or no energy but provide other benefitsCho differ by:Type of building block (3 main ones)Size (# of building blocks; 1 to 100s)Links (chemical bonds) between building blocksCHO terminologySaccharide = building blockSimple CHO = sugarsMono (1) glucose, Galactose, FructoseDi (2): Sucrose, Lactose, TrehalosePolyols: Sorbitol, mannitolOligo saccharides tri (3) - 9Maltodextrins, Raffinose, stachyose, fructooligosaccharydesPolysaccharides:Starch amylose, amylopectin, modified starchesNSPCellulose, hemicelluloseFruit sugar found naturally in fruits and honeySweetness of the sugarsHigh fructose corn syrup used as a sweetenerCan be converted to glucose in the liver

GalactoseRarely occur as a single sugarMonosaccharide in milk sugarCan be converted to glucose in the liver DisaccharidesPairs of mono. linked together In order to be used by the body they must be broken into single sugars3 DisaccharidesLactose Glucose + GalactoseMaltose Glucose + GlucoseSucrose Glucose + FructoseLactoseGlucose + GalactoseFound in milk productsLactose intollerance : inability to break down lactoseMaltoseGlucose + GlucoseAppears where ever starch is being broken downProduct of fermentationSucroseGlucose + FructoseTable sugarObtained from sugar beet and sugar caneFrom disaccharides to mono saccharidesHydrolysis: a molecule of water splits to provide and H and a OH needed to complete the resulting monosaccharidePolysaccharidesComposed of many monosaccharides linked togetherThree poly saccharides of major importance in nutritionGlycogenStarchesFiber - CelluloseGlycogenThe storage form of glucose in animalsStored in liver and muscles, released on demandThere is little glycogen in meat due to rapid breakdown when the animal is slaughteredHighly branched moleculeStarchThe storage form of glucose in plants 3000 or more monosaccharides bound togetherSources are weat, rice, yams, potatoes, peas, and beansDigestible by humansCan beHighly branchedunbranchedFiber - CelluloseThe fiber that forms the basic structure of plantsHuman digestive enzymes cannot break down fiberMost fibers pass through the body without providing energyFiberBacteria can break down some of the fibersInsoluble fiber: not fermented by intestinal bacteriaSoluble fiber: fermented by intestinal bacteriaSoluble fiberSoluble fibers dissolve in waterForm jels (viscous)Easily digested by bacteria in the human colonFound in barley, legumes, fruits, oats, vegetablesAre associated with lower risk of chronic diseasesAdd a pleasing consistency to foodsInsoluble fiberDo not dissolve in waterLess easily fermentedThe outer layers of whole grains contain such as cellulose and hemicellulosesThese fibers retain their structure and texture even after cookingAids in the digestive system and ease elimination