Monosaccharides Disaccharides Simple Carbohydrates Monosaccharides Disaccharides

Monosaccharides Variety of shapes and sizes due to number and arrangements of atoms Hundreds of naturally occurring monosaccharides Only three are commonly found in food (6 carbon atoms) Monosaccharides have a variety of shapes and sizes because the number and arrangements of atoms can vary. There are hundreds of naturally occurring monosaccharides, but the three most commonly occurring are glucose, fructose and galactose. The structures of these differ, but have one thing in common: each contains six carbon atoms. NTK: molecular formula & structural formula

Glucose Most abundant monosaccharide Carbon dioxide + water  glucose + oxygen Functions ATP – immediate use Amino acids (proteins) Glycogen/starch (storage form of carbohydrates) Lipids – long term storage Preferred energy source for the nervous system and the sole source of energy for RBC Photosynthesis = light energy  chemical energy (glucose) Respiration = chemical energy (glucose)  usable chemical energy (ATP)

Fructose Found in honey, fruits and vegetables Five-sided ring structure (hexose) High-fructose corn syrup HFCS Derived from corn (Food Inc.) ~7% of total energy intake in the US 35lbs/15kg of HFCS per year per American Obesity epidemic in the US

Galactose Structurally similar to glucose except for the hydroxyl group on the fourth carbon Found in few food – mostly in lactose Functions Components of cell membrane Synthesis of breast milk Majority is converted to glucose

Disaccharides Glucose is a component in all three disaccharides 2 C6H12O6  C12H22O11 Condensation reaction Glycosidic bond between -OH and –H Types of glycosidic bond determine if a carbohydrate is digestible or indigestible Alpha-glycosidic bond can be digested while beta-glycosidic bond cannot

Lactose Enzymes in mammary glands combine glucose and galactose The only disaccharide with a beta glycosidic bond Maltose Not found in many food, only during starch digestion Enzymes breakdown starch  maltose then bacteria ferment maltose  beer Sucrose Found in sugar cane and sugar beets, processed and crystallized to form sucrose or table sugar

Sugar in Foods Sweetens Thickens Alter textures Naturally occurring sugars are more nutrient dense then artificial ones Limited in nutrition value other than energy ~89 g/22 tsp/355 kcal per day per American Good Eats Functions of sugar includes fermentation, preservation, tenderization, hydrolyzation, etc.

Complex Carbohydrates Oligosaccharides Polysaccharides

Oligosaccharides Found in dried beans, soybeans, peas, etc. Indigestible by humans Functions Components of cell membrane Incorporated into human breast milk If oligosaccharides cannot be digested and absorbed by humans, how do we get them for cell membrane? Humans lack the enzymes needed to digest these two carbohyrateds, they pass undigested into the large intestine, where bacteria break them down. As a result, some people experience abdominal discomfort (bloating, crams and gas) due to the methane and acid produced as waste products. Commercial products such as Beano supply enzyme needed to break down oligosaccharides.

Polysaccharides Examples of polysaccharides? Glycogen – in animals Starch – in plants Cellulose – in plant cell wall (fiber)

Starch Amylose – linear Amylopectin – branched alpha-1, 4 glycosidic bonds Amylopectin – branched alpha-1, 4 in the linear portion alpha-1,6 in the branch joints

http://alevelnotes.com/Carbohydrate-polymers/65

Uncoiled for a Closer Look http://www.vivo.colostate.edu/hbooks/pathphys/digestion/basics/polysac.html

Glycogen Glycogen - branched Stored in alpha-1, 4 in the linear portion alpha-1,6 in the branch joints Stored in Liver Skeletal muscles

Cellulose Cellulose - linear Opposite orientation beta-glycosidic bonds Digestible by intestinal bacteria Total fiber = dietary fiber + functional fiber Soluble and insoluble dietary fiber

Cellulose Soluble Fiber – absorbs water like a sponge Insoluble Fiber Softens feces (otherwise all water will be absorbed by the body) Binds to cholesterol Slows down gastric emptying (feeling full) Insoluble Fiber Increase amount of feces, so body eliminates them sooner

Starch can be linear or branched Cellulose is linear, with monomers in opposite orientations due to beta-glycosidic bonds Glycogen is always branched http://bioweb.wku.edu/courses/biol115/wyatt/biochem/carbos.htm

Diverticulitis Low fiber diet Hard, dry feces Damage mucosa Weak mucosa layer Diverticula form Inflamed diverticula Diverticulitis http://www.funscrape.com/Search/1/diverticulitis.html

http://med.brown.edu/pedisurg/Brown/Image%20bank%20pages/Meckel.html

FDA-approved Health Claims “Diets low in fat and rich in high-fiber foods may reduce the risk of certain cancers.” “Diets low in fat and rich in soluble fiber may reduce risk of heart disease.” “Diets low in fat and rich in fruits and vegetables may reduce the risk of certain cancers.” “Diets low in fat and rich in whole oats and psyllim seed husk can help reduce the risk of heart disease.”

Whole Grain - Rich Source of Fiber Bran – most of the fiber Germ – much of vitamin and minerals Endosperm – mostly starch Refined flour has little bran or germ left = empty calories