View
231
Download
0
Category
Preview:
Citation preview
The Carbohydrates
SugarsStarches
Fiber
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Appendix B
Carbohydrates (CH2O)n
• Simple carbohydrates– Monosaccharides– C6H12O6
• Glucose• Fructose• Galactose
– Disaccharides
• Complex carbohydrates
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Glucose
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Simplified Diagrams of Glucose
The lines representing some of the bonds and the carbons at thecorners are not shown.
In this and other illustrations throughout this book, glucose isrepresented as a blue hexagon.
Another way to look at glucose is to notice that its six carbonatoms are all connected.
Now the single hydrogens are not shown, but lines still extendupward or downward from the ring to show where they belong.
Condensation
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Hydrolysis
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Disaccharides• Maltose• =____________ +____________• Sucrose• =____________ +____________• Lactose• =____________ +____________
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Complex Carbohydrates
• Polysaccharides – Animal (Human) Polysaccharide
•Glycogen– Storage product in animals (Made up of
glucose)– Enough storage for less than a day at rest
or few hours of exercise– Synthesized in liver and muscle– Liver glycogen is available to the rest of
the body but muscle tends to use its own glycogen (more in Ch. 7)
Complex Carbohydrates
• Polysaccharides (Plant)– Starches
•Storage product in plants•Made up of glucose
– Fibers•Provides structure (rigidity) to stems,
roots, leaves etc•Made up of a variety of monosaccharides
and other carbohydrate derivatives
Glycogen & Starch Molecules Compared (small Segments)
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Complex Carbohydrates
• Fibers (Structure)– Cellulose
• Made up of glucose• Different type of bond
– Hemicelluloses• Found in Cereal Fibers• Various monosaccharides
– Pectins• One type of
monosaccharide• Form gels• Used to thicken jelly
(jams)
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Link cannot be broken by human digestive enzymes
Complex Carbohydrates
• Fibers– Gums and mucilages
• Guar Gum, Gum arabic (Gums)• Psyllium, Carrageenan (Mucilages)
– Lignin• Carrots• Seeds of strawberries
– Resistant starches• Whole legumes• Raw potatoes• Unripe bananas
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Complex Carbohydrates
• Fibers– Soluble fibers
•Viscous•Fermentable
– Insoluble fibers•Nonviscous
• (Phytic acid)– Not classed as fiber– Reduces absorption of minerals (e.g. iron in
cereals may not be absorbed well)• Everything you want to know about fibre
– http://www.nlm.nih.gov/medlineplus/dietaryfiber.html– http://www.hsph.harvard.edu/nutritionsource/fiber.html
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Fiber
• Fiber health benefit– Managing IBS ( normalizes bowel function i.e. keeps you
regular– Shown to lower LDL ("bad") blood cholesterol levels,– Reduce the risk of heart disease,– Minimize colon cancer risks (This has been questioned
recently)– Slow the absorption of fats and carbohydrates into the
bloodstream, which» improves glycemic control » helps prevent the formation of free radicals. » lowers insulin requirements.
• Commercial fiber products– Acacia is gum arabic, Metamucil and Fybogel contain psyllium, Citrucel
contains methylcellulose, Equalactin and Fibercon contains calcium polycarbophil, Benefiber contains guar gum, and FiberChoice contains inulin.
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Digestion• Mouth
– Salivary amylase• Stomach
– Fibers and satiety• Small intestine
– Maltase, sucrase, lactase• Pancreas
– Pancreatic amylase• Large intestine
– Fermentation of viscous fibers•Water, gas, short-chain fatty acid
production
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Digestion• Available carbohydrates vs.
unavailable carbohydrates (fiber)
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Carbohydrate Digestion in the GI Tract
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Absorption
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Lactose Intolerance• Symptoms
– Bloating, abdominal discomfort, diarrhea• Causes
– Lactase deficiency• Prevalence
– Less among Northern Europeans – More among Native North Americans and
Southeast Asians• Dietary changes
– Does not require the elimination of milk/milk products
– Can use fermented milk products• Yogurt and Acidophilus milk
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Glucose in the Body• Energy
• Glycoproteins
• Glycolipids
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Carbohydrate Metabolism
• Storing glucose as glycogen
• Using glucose for energy
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Complex Carbohydrates
• Polysaccharides – Animal (Human) Polysaccharide
•Glycogen– Storage product in animals (Made up of
glucose)– Enough storage for less than a day at rest
or few hours of exercise– Synthesized in liver and muscle– Liver glycogen is available to the rest of
the body but muscle tends to use its own glycogen (more in Ch. 7)
Carbohydrate Metabolism
• Making glucose from protein– Gluconeogenesis– Protein-sparing action of
carbohydrates
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Carbohydrate Metabolism
• Making ketone bodies from fat fragments– Ketone bodies
•Ketosis–Acid-base balance
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Carbohydrate Metabolism
• Converting glucose to fat– Energetically expensive
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Constancy of Blood Glucose
• Regulating hormones– Insulin– Glucagon– Epinephrine
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Maintaining Blood Glucose
Homeostasis
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Constancy of Blood Glucose
• Diabetes– Type 1 diabetes
•Failure of insulin production– Type 2 diabetes
•Obesity
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Constancy of Blood Glucose
• Hypoglycemia– Rare in healthy people
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Constancy of Blood Glucose
• Glycemic response– Glycemic index
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Sugars• Added sugars
– Sucrose, invert sugar, corn syrups, etc.
• Health effects of sugars– Nutrient deficiencies
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Sugars
• Health effects of sugars– Dental caries
•Dental plaque
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Accusations Against Sugars
• Sugar causes obesity• Sugar causes heart disease• Sugar causes misbehavior in
children and criminal behavior in adults
• DRI– No more than 25% of total
daily energy intake
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Accusations Against Sugars
• Sugar causes cravings and addictions– serotonin
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Starch and Fiber• Health effects
– Heart disease
– Diabetes– GI health
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Starch and Fiber• Health effects
– Cancer– Weight management– Harmful effects of excessive fiber
intake
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Viscous Fibers• Soluble and more fermentable• Gums and mucilages• Pectins• Psyllium• Some hemicelluloses
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Viscous Fibers• Sources
– Whole-grains, fruits, legumes, seeds and husks, vegetables
– Extracted and used as food additives
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Viscous Fibers• Lower blood cholesterol
• Slow glucose absorption
• Slow transit of food through upper GI tract
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Viscous Fibers• Holds moisture in stools, softening
them
• Yield small fat molecules that the colon can use for energy
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Viscous Fibers• Lower risk of heart disease
• Lower risk of diabetes
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Viscous Fibers
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Nonviscous Fibers• Insoluble and less fermentable• Cellulose• Lignins• Psyllium• Resistant starch• Many hemicelluloses
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Nonviscous Fibers• Sources
– Brown rice, fruits, legumes, seeds, vegetables, wheat bran, whole grains
– Extracted and used as food additives
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Nonviscous Fibers• Increase fecal weight
• Speed fecal passage through colon
• Provide bulk and feelings of fullness
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Nonviscous Fibers• Alleviate constipation
• Lower risks of diverticulosis, hemorrhoids, appendicitis
• May help with weight management
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Nonviscous Fibers
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Starch and Fiber• RDA for carbohydrate
– 130 g/day– 45% - 65% total daily energy
intake
• Daily Value: 300 g/day
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Starch and Fiber• Fiber
– Daily Value: 25 g/day– AI: 14 g/1000 kcal/day
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Guidelines to
Groceries
• Grains
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Guidelines to Groceries
• Vegetables
• Fruits
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Guidelines to Groceries
• Milk and milk products
• Meats and meat alternatives
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Alternatives to Sugar• Artificial sweeteners vs. sugar
replacers (nutritive sweeteners)
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Alternatives to Sugar• Saccharine and cancer• Aspartame and PKU
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Alternatives to Sugar• Stevia
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Alternatives to Sugar• Acceptable Daily Intake (ADI)
• Artificial sweeteners and weight control
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Recommended