Carbohydrates• Functions:• 1) Primary function = provide Energy• 2) Structural components of body:

• I.e., cartilage

• 55- 60% of kcal of diet

• General Formula: CH20

Classes of Carbohydrates

• 1) Simple CHO’s• Single or double sugar units (saccharides)

• 2) Oligosaccharides• 3 to 10 saccharide units

• 3) Complex CHO’s• Usu 1,000’s of saccharide units long

Simple CHO’s Complex CHO’s

• Monosaccharides– Glucose– Fructose– Galactose

• Disaccharides– Maltose– Lactose– Sucrose

• Starch • Glycogen• Fiber

• Oligosaccharides• Inulin• fructoligosaccharide

Simple CHO’s

• Almost exclusively in plant foods

• Found in fruits, sweets, milk and milk products, table sugar

MonosaccharidesSimplest CHO’s

• Building blocks of all CHO’s

• Glucose: most common– aka dextrose, blood sugar

• Fructose: fruits, honey, high-fructose corn sugar

• Galactose: part of milk sugar (lactose)

O

O H

H

C H 2 O H

H O

O H

HH

H O C H 21

2

34

5

6

O

1

23

4

5

6C H

2O H

O H

HO HH O O

H

H

H

HH

O

1

23

4

5

6C H

2O H

O H

HO H

H O

O H

H

H

H

H

Glucose Fructose Galactose-mildy sweet -hardly sweet-Intensely sweet

O

1

2

6

3

4

5

C H 2 O H

O

1

2

6

3

4

5

C H 2 O H

O

O

1

2

6

3

4

5

C H 2 O H

OH O C H 2

C H 2 O H

O

1

2

6

3

4

5

O O

O

C H 2 O H C H 2 O H

Glucose + glucosemaltose

Galactose + glucoselactose

Glucose + fructosesucrose

Disaccharides

Maltose

Lactose

Sucrose

maltase

lactase

sucrase

O

O H

C H 2 O H

O

H O

C H 2 O H

O H H O

glucose + glucose

O

1

2

6

3

4

5

C H 2 O H

O

1

2

6

3

4

5

C H 2 O H

galactose + glucose

O

1

2

6

3

4

5

C H 2 O H

O

1

2

6

3

4

5

C H 2 O H

O

O

1

2

6

3

4

5

C H 2 O H

OH O C H 2

C H 2 O H

O

1

2

6

3

4

5

O O

O

C H 2 O H C H 2 O H

O

1

2

6

3

4

5

C H 2 O HOH O C H 2

C H 2 O H1

2

6

3

4

5

glucose + fructose

Complex CHO’saka Polysaccharides

• Starch– In plant foods – major E reserve for plants– = glucose + glucose + glucose etc.– About 3,000 glucose’s bonded together

• 2 Forms of starch:– 1) amylose– 2) amylopectin

Amylose

• Straight chain of glucose’s

• 1--> 4 bonds

O O O OO O O

Amylopectin

• Branched chains of glucose’s:

• 1--> 4 bonds

• 1--> 6 bonds at branch points

O O O OO O O

O O

Complex CHO’saka Polysaccharides

• Glycogen– Animals synthesize this and store it in liver

and muscle– = glucose + glucose + glucose etc.– 1-->4 bonds and 1-->6 bonds

O O O OO O O

O O

Amylopectin vs. Glycogen

Made by plants Made by animals

Branched VERY HIGHLY Branched

1 --> 4 1 --> 4

1-->6 1 --> 6

ProteinLipidsInorganic substances

LigninCelluloseHemicellulosePectins

GumsMucilagesAlgal polysaccharidesSuberinCutin

PlantCell Wall

Non-cell wall plant parts

DietaryFiber

Complex CHO’saka Polysaccharides

• Fiber– Cellulose = very common fiber– = glucose + glucose + glucose etc.– 1-->4 bonds

O

O O

C H 2 O H C H 2 O H

O O

O

C H 2 O H C H 2 O H

O Etc...Etc...

Fiber

• NO Human enzymes can break down fiber

• Bacterial enzymes in intestines can break down fiber

Dietary Fiber

Soluble Insoluble

SomeHemicellulose

Pectin

Gums

MucilagesLignin

CelluloseSome

Hemicellulose

Soluble Fibers

adsorptionor binding

of

Fecal bile acids

Lipid absorption

Serum cholesterol

Bileacids

Lipid

Minerals

Altered mineral balance

Soluble Fibers

GelFormation

Transit Time

Nutrient Absorption

Gastric Emptying

Slow Glucose Absorption

Feeling ofFullness

Insoluble & soluble Fibers

Water-holdingcapacity

Fecal volume

Colon Transit Time(speed movemn’t thru gut)

Defecation Frequency( constipation)

Insoluble & Soluble Fibers

Fermentability/Degradability

Colonic Na+ and H2O absorption2˚ bile acid

synthesis

Lactate

GI Lumenacidification

Short ChainFatty Acids

Inhibit TumorFormation

EnterocyteEnergy

Mucosal CellProliferation

Fiber in Foods:

• In general, whole, unprocessed foods contain more fiber than their processed versions

• Most fiber-rich foods have a mix of various types of fibers

• Require about 25 to 35 grams/day

Fiber in Foods:Processing of foods

Apple = 5 g

Applesauce = 2 g

Apple juice = 0.2 g

Increasing Fiber in the Diet:

Consumption of veggies, fruits, beans, whole-grain products

• Whole fruits instead of fruit juice

• Use whole-grain flour instead of white flour

• Brown rice instead of white rice

Dilute CHO’s vs. Concentrated CHO’s Sugar in Fruit vs. Sugar in Candy

This Sugar comes with

Vitamins, Minerals and Fiber

NO fiber or very little

Typically fewVitamins and Minerals/kcal

Ingredients List:

• Sucrose• Glucose• Maltose• Dextrose• Fructose• High-fructose Corn

Syrup

• Brown Sugar• Honey• Confectioner’s

Sugar• Invert Sugar• Levulose• Raw Sugar• Turbinado Sugar

Sugar Intake Guideline

• < 10% of total kcal

• This applies to concentrated refined sugars (I.e., candies, sweets),not fruits or milk products

Suggestions to Reduce Sugar Intake:

• Substitute Water or Fruit Juices for soft drinks

• Unsweetened cereals

• Reduce sugar in recipes

• Use sweet spices, I.e., allspice, anise, cinnamon, ginger, vanilla, coconut

Dental Caries

• Bacteria feast on sugars and release acids that decay tooth enamel

• Not only the amount of sugar eaten

• How much the food clings to teeth

• How frequently eaten

• Baby bottle syndrome

Digestion of CHO’s

• Digestion begins in mouth, w/ salivary amylase

• Fiber delays gastric emptying

• Pancreatic amylase

• Lactase, maltase, sucrase are brush border enzymes (made by sm. Intestines)

The Fate of CHO’s in your body:• 1) satisfy immediate energy needs of all

your cells

• 2) Extra CHO’s converted to glycogen and stored in muscles and liver

• 3) Extra CHO’s converted to fat in liver and stored in adipose cells

Maintaining Blood Glucose Levels

• Critical to maintain blood glucose

• Too low ---> shaky, weak, headache

• Too high ---> sleepy, chronically high causes organ damage

Eat a Meal

Blood Glucose

Pancreas releasesInsulin

Liver picksup glucose Muscle picks

up glucose

Adipose picksUp glucose

Results in Blood Glucose

Fasted

Blood Glucose

Pancreas releasesGlucagon

Liver breaksdown glycogen Muscle breaks

down glycogen

Adipose releases fat

Results in Blood Glucose

When Blood Glucose is Low, A Snack with CHO, Fat and Protein is Best:

• CHO: good source of glucose and stimulates insulin secretion

• Protein: stimulates glucagon which opposes insulin to prevent the body cells from picking up too much glucose too fast

• Fat:slows digestion --> slows absorption

Serum Cholesterol:

• Strongest Hypocholesterolemic Effect:– Psyllium, Guar Gum, Oat Gum

• Moderate Hypocholesterolemic Effect:– Oat Bran, Soybean fibers

• No Hypocholesterolemic Effect:– Wheat, Corn, Rice Brans

Hypoglycemia

• Abnormally low blood glucose level

• Symptoms =

• Recommend:

Diabetes

• IDDM (insulin-dep. diabetes mellitus)

• Aka: juvenile onset, type I

• About 10% of all cases

• NIDDM (non-insulin dep. Diabetes mellitus)

• Aka: adult-onset, type II

• About 90% of all cases

• 2x the risk to heart dx.• Majority obese

- a major cause of blindness, kidney failure, amputations, male impotence

Diabetes Risk for Women:

• Overweight women 8 times more likely to get diabetes than normal weight women

• Obese women 20 times more likely to get diabetes than normal weight women

• Women who do ≥ 7 hours moderate exercise/wk, 30% lower risk than women who exercise < 1/2 hour / wk

• Diets: high fiber & PUFA’s, low in SFA and trans fats 50% lower risk

NEJM, 2001, 345, 785, 829; J Nat Cancer Inst, 2001, 93, 937

Number of New Diabetes Cases (NIDDM) 0-19 years

J Pediatr, 1996, 128,608-615

Number of New Diabetes Cases (NIDDM) 10-19 years

J Pediatr, 1996, 128,608-615

Percentage of New Diabetes (NIDDM) Cases, 0 - 19 years

J Pediatr, 1996,128,608-615

Rising Incidence of NIDDM in Youth• 0-19 year olds:

– Before 1992, 3-4% of all new cases of diabetes were NIDDM

– After 1992, 16% of all new cases of diabetes were NIDDM

– 4 - fold INCREASE

• 10-19 year olds:– Before 1992, 3-4% of all new cases of diabetes were

NIDDM– After 1992, 33% of all new cases of diabetes were

NIDDM– 10 - fold INCREASE

Increased risks for Diabetics:

• Hypertension

• Coronary Heart

Disease

• Stroke

• Amputations

• Blindness

• Kidney, liver damage

Blood Glucose Levels:• Normal: 70 - 110 mg/dL of blood

• Below 40 mg/dL (2.2mmol/L) --> coma, seizure, death

• Above approx. 180 mg/dL (10 mmol/L) -->– Immediate effects: glycosuria, caloric loss,

thirst, hunger– Chronic effects: renal, retinal, nerve, blood

vessel damage

Blo

od g

luco

se (

mg/

dL

)250

200

150

100

50

Time (hours)1 2

Diabetes

Normal

ReactiveHypoglycemia

Glycemic Index

• = a quantitative ranking of foods based on their postprandial blood glucose response (above fasting glucose) compared to a reference food

• The reference food is either:– White bread (50 g available cabohydrate)– Glucose (50 g)

Glycemic Response

White BreadSpaghetti

50

25

0

-25Δ , /Plasma Glucose mg

dL

InsulinemicResponse,Time min

,Time min

0306090120150180

030609012015018050 g CHO

Eur J Clin Nutr,1991,45,489-99,,JAMA 2002,287,2414-23

Factors that affect a food’s GI

• Particle size: as particle size : GI

• Differences in cooking

• Starch composition: amylose v. amylopectin

• Fiber content

• Ripeness

• Food processing

Application of GI• Diabetes: the GI helps in control of blood

glucose and insulin responses

• Sports performance: Different GI foods more effectively replenish glycogen stores after exercise: High GI foods replenish glycogen better than low GI foods

• Appetite Research: Low GI foods produce greater satiety than high GI foods

Obese Children

High GI meal(instant oatmeal)

Low GI meal(steel cut oats)

(Identical energy & macronutrient intake)

Ad libitum energy consumption monitored throughout rest of day

Energy intake 53% HIGHER in High GI group

Result:

Ludwig et al., Pediatrics, 1999, 103, E261-66