Chapter 4- The Carbohydrates- Sugar, Starch, Glycogen and Fiber PDF

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Carbohydrates Overview:  Carbs  Proteins  Lipids Carbs: 

All large organic macromolecules that provide energy

Energy needs, especially brain/nervous system

 Energy for body  Fibre adds bulk to food- good for G.I. Simple or Complex Carbs: body’s most important energy source 1. Monosaccharide- single sugar units 2. Disaccharide- two sugar units 3. Polysaccharides- three or more sugar units (refer to chp 4 help notes slide 1) Simpler complex to more complex needs energy = synthesis Hydrolysis- gives off energy Monosaccharide joins together to form disaccharide Fig 4.2 Fig 4.3 Glucose molecules are the building blocks of polysaccharide Starch and Glycogen: have enzymes to break these bonds Cellulose- does not have enzymes Where does glucose come from? Photosynthesis (refer to slide 2) Fig 4.1

Light energy

Activates chlorophyll Energy to fix CO2 Glucose (energy trapped in C-C bonds)

Plants use/ Animal use

(Refer to slide 3) where atoms end up in photosynthesis Terminology: Carbohydrates:  Simple sugars? Monosaccharide and disaccharide  Complex sugar Naming:   

By # of carbons By # sugars linked (mono, di, poly) By “ose” ending “ose”= sugar “ase”= enzyme I. Nutritionally Important Carbohydrates

A. Sugars 1. Monosaccharide: molecule formula  C6H12O6 a. Glucose- most important for the body b. Fructose- found in fruits/veggies c. Galactose- part of lactose -not free in nature - found in milk and honey (refer to slide 4) Important monosaccharide.

2. Disaccharides Two monosaccharide link a. Lactose- Glucose + galactose (Milk) b. Maltose- Glucose + Glucose (Beer) c. Sucrose- Glucose + Fructose (Sugar) Formed by dehydration synthesis - H2O removed to join monosaccharides - Energy required? Yes (refer to slide 5) Disaccharide B. Polysaccharides Polymers of monosaccharide (macromolecule) Minimum of 3 a few thousand Formed by dehydration synthesis Starch: o o

insoluble Carb storage (plants)

o o o

“Animal starch” not part of our diet stored in liver and muscle

Glycogen:

Fiber: o Most indigestible o Structure and suppose (plants) o Soluble and insoluble forms (refer to slide 6+7) -Starch- have enzymes to break -Cellulose- lack enzymes to break II. The need for Carbs- Recommendations A. Carbs and weight gain Popular Media  carb are fattening food -

actually best fuel for body brain and CNS choose wisely complex VS simple carb- Nutrient density complex=fibre Evidence refined sugars increased appetite/disease

Beware the low cal diets. Why? -slows down metabolism - burn protein in faster range -build up of ketones Remember: B. 1.

carbs cheap you can eat more complex carbs needed to “burn fat” Fiber and Health Dietary Fiber (e.g. cellulose) -we cannot digest (lack of enzyme) - most are low calories - benefits vary with fiber type & bacteria

2. Types of Fiber (Table 4.2 pg. 120) a. Soluble (viscous) fibers- Dissolves in h2o o come from plant cells o sources include: barley, oats, oat bran, etc. o bacteria can easily digest (in colon) e.g. gum, pectin, psyllium b. Insoluble Fibers o from tough plant cell waslls what is this composed of? Cellulose, lignin Sources: wheat bran, fruits, legumes, etc (refer to Characteristics of Fibre on BB) Characteristics, sources and health effects of fiber (Table 4.2) Fig 4.4 everything has (insoluble/soluble fibre) 3. Health Effects of Fiber a. Research Status Burkitt – the first fiber hypothesis British vs. Ugandans Fiber in diet ‘hot topic’ – what you eat  genetic expression 

Health benefits of soluble fibers o Soluble fibre fermented in colongas and short chain fatty acids (butyrate)ABSORBhealth effects o Roles of butyrate (and similar chemicals):

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o o o

Decrease colon cancer  Development of colon cancer  Butyrate from fibre breakdown may help protect colon: o Barriers of mucosa improved  less likely for stuff to stuck to the surface  less likely for inflammation) o Makes colon more acidic  Less likely for polyps to form o Prebiotic- increase ‘good’ bacteria o Well-fed colon cells actively dividing and replacing lining more frequently o Another way that soluble fiber lowers cholesterol  Enterohepatic circulation of bile salts  Fig 4-5, page 121-122 Health benefits of insoluble (non-viscous) fiber o Primarily in large intestine  Absorb H2O  Increase fecal bulk  Speeds up transit time (large intestine)  Increase strength  Decreases  Diverticulosis (fig 4.6)  Appendicitis  Hemorrhoid o Recommendations  WHO- 25+g / DRI (varies by age & sex) pg. 119  Best source? (fig 4.4; 4.15)  Whole food (added fibre, Metamucil)  Too much= malnutrition o Binds minerals/prevents absorption o Dehydration o

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Lower diabetes risk:  In pancreasaffect insulin release  In livercontrol glycogen levels  Lower blood cholesterol  In liversupresses cholesterol synthesis  Butyrate stimulates immune response  Butyrate and related moleculesenergy source for colon cells Slows transit through upper gastrointestinal tract- feel fulldelays glucose apsorption Holds H2O in stoolssoftens Displace fatty foods in diet weight management

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Chew well and increase intake gradually  If increase fibre, increase water too

From Carbs to Glucose (overview- fig 4.10 pg. 129) 

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Digestion and absorption of carbohydrate o Starch and disaccharides must be digested to monosaccharidesabsorbed o Absorbed carbohydrate is either:  Already glucose  Converted to glucose (liver)  Polysaccharides are broken down to disaccharides via amylase in the lumen in the small intestine  Enzymes (on the brush border) take in the disaccharides and break them down to monosaccharides which are then absorbed in the epithelial cell and sent to the liver through the blood  Converted to fat o Overview of carb digestion and abruption (pg. 129)  Begins in moughtenzyme  Salivary amylase  Completed in small intestineenzyme  1st lumen: pancreatic amylase  2nd Brush Borderenzymes o Sucrose, lactase maltase  3rd absorbedbrings to liver through blood  Absorbed monosaccharides converted to glucose by liver  Indigestible carbs  Resistant starch  Fibers  move into the colon Problems with digestion o Lactose intolerance  Missing/mom-functional enzyme.  What is milk sugar?  Lactose (lastase)glucose & galactose are absorbed into blood  If intolerant, lactose goes undigested into the large intestine… not good. It’s not supposed to be there  Lactose pulls H2O into lumen (osmosis)  Colonic bacteria feasts on lactose, leading to gas & chemicals (irritating)  Develops gradually  Incidence 75% globally (pg. 130)  Symptoms  Often exaggerated

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Treatment  Dietary- drink milk with other foods  Dairy alternatives  Enzyme treatment/replacement o Ex. Pre-digested dairy Body’s use of Glucose o Why are carbs essential in our diet? o Splitting glucose for energy  In cells: break bonds between carbon atoms (cellular respiration 1 glucose= 36 ATP)  Brain needs glucose  Fig 4.11 Not enough carbs? (fig 9.11) o Convert proteincarbs to use as fuel wasteful o Use fat as a fuel- inefficient as incomplete breakdown forms ketones (ketosis) can lower blood pH Adequate carb intakes: o Carb plentiful (i.e. carbs + fats)’normal’ fat digestion- energy available, NO ketones Storing glucose as glycogen Regulating glucose levels in the blood (fig 4.12) o Carefully regulated (brain) o Pancreatic hormones  Insulin  Glucagon o Pg. 133 o Glycemic effect- emic=blood  Extent that food increase blood sugar levels and blood insulin levels  Glycemic index (GI) fig 4.12 pg 119  Foods potential for increasing the blood glucose level relative to a standard value (50g glucose in water)  GI= test/standard  Glycemic load o GI x absorbable carbs (g) (actually consumed)  Glycemic effect is complex  Varies by: o Raw vs. cooked o Eaten alone or with food o Previous meal contents o Body size/ weight/ blood volume/ metabolism etc. Converting glucose to fat o Glucosefat IF:

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 Blood glucose high  Glycogen space full REMEMBER:  Humans convert glucose to fat; cannot convert fat to glucose!

Problems 

Diabetes mellitus (Type I & II) o Mellitus from “honey” o Named after “sweet tasting urine” o What happens when you have diabetes? Fig 4.7; 4.8  Results in hyperglycemic (increase in blood glucose)  Low insulin/resistance to insulin  Excess urine/thirst  Glucose in urine  Cells starved o Fatigue, weight loss o Crave sweets o Ketosis  Prone to infection/slow to heal  Vision disturbed  Age 40+, routine screening. Diagnosis by glucose tolerance test o Type 1 (juvenile-onset, insulin dependent)  Not coming (10-20%)  Not obese, it is an autoimmune disorder- destruction of beta cells  Treatment  Must take insulin  UofA is a world research center o Type II (adult-onset, non-insulin dependent)  Most common (80-90%)  Produce insulin; target cells are less sensitive to insulin  Body fatness (obesity) connectionpredictive  Increased sugar in the diet is much less predictive than obesity  Increased obesityincrease insulin resistance fig 4.14  Elevated blood glucose (cells starved for glucose)  NOWelevated blood lipid levels (fuel cells)  NOWover-abundance of blood lipidincrease fat storage (worsens obesity)  Treatment:  Prevent/ treat body weight problems  Take drugs o Stimulate insulin release

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o Increase glucose uptake Be proactive with proper nutrition (pg. 139) Exercise! Increase tissue sensitivity to insulin... Helps us to get glucose into active muscles without the use of insulin

Hypoglycemia o Postprandial or reactive hypoglycemia  RARE- occurs after eating  Temporary  2-5 hours after eating  General symptoms  Blood glucose levels? o Treatments  Eat frequent well balanced meals o True (fasting) hypoglycemia  Extremely rare  Hormonal problems  Pancreas tumors/other diseases  Persistent symptoms  Treatment  Treat underlying cause o Ex. Cancer, pancreatic damage, uncontrolled diabetes, liver damage, hepatitis

Sources of carbohydrates 

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Which food has absolutely no carbs? o Fat o Meat, poultry, fish, eggs Good source? Plants! o Legumes are great sources o Corn o Bananas

Sugar and Alternative Sweeteners: Are they bad for you? Sugar in the Diet  

Consumption rates (fig C4.1) Sugar national issues o Obesity o Diabetes  High body fatpredictor of type 2

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o Heart disease o Behaviour o …sometimes complex o Dental caries- type & time exposed (fig C4.2) One generalization o No harm to reducing empty calories (ex. Pop) WHO recommends...