1 dnt 200 nutrition for health sciences carbohydrate

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DNT 200NUTRITION FOR HEALTH

SCIENCES

CARBOHYDRATE

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CARBOHYDRATE

Things sweet to taste prove in digestion sour.Shakespeare, King Richard II

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CARBOHYDRATE

DEFINITION

Carbohydrates are compounds composed of carbon, hydrogen

and oxygen arranged as monosaccharides or

multiples of monosaccharides (disaccharides & polysaccharides)

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CARBOHYDRATE

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CARBOHYDRATE

SIMPLE CARBOHYDRATES

Monosaccharides (single sugars)

Glucose– Also known as

• Blood sugar

• Grape sugar

• Dextrose

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CARBOHYDRATE



Glucose (continued)

Plants capture the sun’s radiant energy and through photosynthesis, trap this energy in glucose

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CARBOHYDRATE



Glucose (continued)– Is common to all disaccharides and

polysaccharides– Is the chief fuel of the body’s cells

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CARBOHYDRATE



Fructose– Also known as levulose

– Is the sweetest of sugars

– The body can convert fructose to glucose or can break it into fragments from which fat can be made

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CARBOHYDRATESIMPLE CARBOHYDRATES

Fructose• Endocrine and metabolic effects include an increased risk

for insulin resistance and hyperinsulinemia• Common sources

– Sucrose– High fructose corn syrup

• Cheaper than sucrose• Represents the biggest change in our diets in the last 15 years• Used in sodas, juice boxes, bread, and a host of other foods

– Natural sweeteners high in fructose (e.g. honey) are not associated with the above cited negative changes

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CARBOHYDRATE



Galactose– Does not appear singly in

nature

– Found only as a part of lactose

– During digestion, galactose is freed as a single sugar

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CARBOHYDRATE


Disaccharides (double sugars)• Are pairs of single sugars linked together• A condensation reaction is one where two

reactants combine to yield a larger product such as when two monosaccharides link together to form a disaccharide and a molecule of water is created

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CARBOHYDRATE


Disaccharides (double sugars)• A hydrolysis reaction is one where a major

reactant is split into two products such as when a disaccharide is cut in two with a molecule of water forming two monosaccharides

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CARBOHYDRATESIMPLE

CARBOHYDRATES

Disaccharides (double sugars)

Maltose– Consists of two glucose units

– Is a plant sugar -- is a minor constituent in a few foods to include malt and germinating cereals

– Also known as malt sugar

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CARBOHYDRATE


Disaccharides (double sugars)Sucrose

– Most familiar of the three disaccharides

– Consists of one glucose unit and one fructose unit

– Also known as table or white sugar– Is usually obtained by refining the

juice from sugar beets or sugar cane to provide the brown, white, and powdered sugars

– Also occurs naturally in many fruits and vegetables

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CARBOHYDRATE


Disaccharides (double sugars)

Lactose

– Consists of glucose and galactose

– Is the principle carbohydrate of milk

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CARBOHYDRATE


Disaccharides (double sugars)Lactose

Lactose intolerance is the condition that results from an inability to digest the milk sugar lactose. It is characterized by bloating, gas, abdominal discomfort and diarrhea

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CARBOHYDRATE

COMPLEX CARBOHYDRATES

Energy Yielding Polysaccharides

Starch– Is the main storage material of

plants– Is composed of hundreds of

glucose units linked together– When you eat a plant, your

body splits the starch into glucose and uses the glucose for energy

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CARBOHYDRATE

COMPLEX CARBOHYDRATES

Energy Yielding Polysaccharides

Starch (continued)

Food Sources of Starch

– Grains (wheat, rice, corn, etc.)

– Legumes (peanuts, dry beans, dry peas)

– Root Vegetables (potatoes, yams)

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CARBOHYDRATECOMPLEX CARBOHYDRATES

Energy Yielding PolysaccharidesGlycogen

– Is the storage form of glucose– Also composed of glucose units -- more complex

than starch and highly branched

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Energy Yielding PolysaccharidesGlycogen

– Not important as a food source of carbohydrate– Found in meats only to a limited extent -- does not

occur in plants– Made and stored by the liver and muscle tissues– Is the form in which the human body stores much of

its glucose

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Non-Energy Yielding PolysaccharidesFibers

– Are the structural parts of plants– Are non-starch polysaccharides (and some non-

polysaccharides)– Not digested by human digestive enzymes (some are

digested by GI tract bacteria)– Can be classified as soluble or insoluble, depending

on their solubility in water

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CARBOHYDRATECOMPLEX CARBOHYDRATE

Non-Energy Yielding PolysaccharidesType of Fiber Major Food

SourcesAction in the Body

Soluble FibersGums, pectins,somehemicelluloses,mucilages

Fruits (apples,citrus), oats, barley,legumes

Delay GI transit (benefitsdigestive disorders)Delay glucose absorption(benefits diabetes)Lower blood cholesterol(benefits heart disease)

Insoluble Fibers

Cellulose, manyhemicelluloses,lignins

Wheat bran, cornbran, whole-grainbreads and cereals,vegetables (such ascabbage, carrots, andbrussels sprouts)

Accelerate GI transitIncrease fecal weight(promotes bowelmovements)Slow starch hydrolysisDelay glucose absorption

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Non-Energy Yielding PolysaccharidesFiber Terminology

– Dietary Fiber -- Edible, non-digestible components of carbohydrates and lignin naturally found in plant food. Examples include cereal bran, flaked corn cereal, sweet potatoes, legumes

– Functional Fiber -- Fiber sources shown to have similar health benefits as dietary fiber, but are synthetic. Examples include pectin extracted from citrus peel and used as a food ingredient

– Total Fiber -- Dietary fiber + Functional fiber

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CARBOHYDRATE

CARBOHYDRATE METABOLISMStored Glucose

• Glycogen stored and released by the liver -- only a few hours worth is stored)

• Falling blood glucose signals that body cells need glucose -- liver cells dismantle glycogen into single molecules of glucose, which is released into the bloodstream

• Muscle cells can also store glycogen (about 2/3 of the body’s supply) but it is used by these cells for start-up and intensive exercise

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CARBOHYDRATE

CARBOHYDRATE METABOLISM

Using Glucose for Energy

• When glucose enters a cell, enzymes break it in half– The halves can be put back together again to make

glucose OR– Can be broken down into smaller fragments

• Fragments– Can yield energy when broken down completely into CO2

and water OR– Can be reassembled into units of body fat

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CARBOHYDRATE

CARBOHYDRATE METABOLISMMaking Glucose From Protein

Gluconeogenisis -- is when glucose is made from a non-carbohydrate source

• Making glucose from protein– Body protein can be converted to glucose

(gluconeogenisis)

• Body fat cannot be converted to glucose to any significant extent, although fat breakdown can yield energy for many of the body’s cells

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CARBOHYDRATE

CARBOHYDRATE METABOLISMMaking Glucose From Protein

• Only glucose can provide energy for:– Brain cells

– Other nerve cells

– Developing red blood cells

• Only adequate dietary carbohydrate can prevent the use of protein for energy -- this role of carbohydrate is known as its protein sparing action

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CARBOHYDRATECARBOHYDRATE METABOLISMMaking Ketone Bodies From Fat Fragments

Ketone Bodies -- the product of incomplete breakdown of fat when glucose is not available in the cells

• Inadequate carbohydrate may result in more fat being broken down -- but not all the way to energy

• Fat fragments combine with each other, forming ketone bodies– Muscles and other tissues can use ketone bodies for energy– When production of ketone bodies exceeds their use, they

accumulate in the blood causing ketosis, which disturbs the body’s normal acid-base balance

• 50-100 grams of carbohydrate per day spares protein and prevents ketosis

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CARBOHYDRATE

CARBOHYDRATE METABOLISMConverting Glucose to Fat

• Given more carbohydrate than it needs the body– Uses glucose for energy needs

– Fills glycogen stores to capacity

• Leftover is broken down by the liver (along with protein and fat fragments) into smaller molecules – Are then re-assembled as fat and stored

– A minor pathway compared to the conversion of dietary fat to body fat

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CARBOHYDRATE

BLOOD GLUCOSEMaintaining Homeostasis

Homeostasis -- the maintenance constant internal conditions by the body’s control systems

• Glucose must be maintained within limits that allow cells to nourish themselves– Too low and you become dizzy and weak– Too high and you become confused and have difficulty

breathing– Extremes left untreated can result in death

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CARBOHYDRATEBLOOD GLUCOSEMaintaining Homeostasis

Blood Glucose Regulators– Insulin -- a hormone secreted by the pancreas in response

to (among other things) increased blood concentration• Circulating insulin contacts the receptors in the body’s cells --

receptors respond by ushering glucose from the blood into the cells

• Most of the cells take only the glucose they can use for energy right away

• The liver and muscle cells can assemble the small glucose units into long branching chains of glycogen for storage

• The liver can also convert glucose to fat for export to other cells

• Thus, high blood glucose returns to normal as excess glucose is stored as glycogen and fat

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CARBOHYDRATEBLOOD GLUCOSE

Maintaining HomeostasisBlood Glucose Regulators (continued)Glucagon -- a hormone secreted by the pancreas

in response to low blood glucose concentrations that elicits the release of glucose from storage

• Glucagon signals the liver to dismantle its glycogen stores and release glucose into the blood for use by all the other body cells

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CARBOHYDRATEBLOOD GLUCOSE

Maintaining HomeostasisBlood Glucose Regulators (continued)

– Epinephrine -- a hormone secreted by the adrenal gland that modulates the stress response• Formerly called adrenaline• Acts quickly when a person experiences stress,

ensuring that all the body cells have energy fuel in emergencies

• Like glucagon, epinephrine works to return glucose to the blood from liver glycogen

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CARBOHYDRATE

BLOOD GLUCOSE

Maintaining HomeostasisBalancing within the Normal Range

– When blood glucose falls too low• Replenished by food

• In the absence of food, glucagon can signal the liver

to break down glycogen stores

– When blood glucose rises too high• Insulin can signal the cells to take in more glucose for

energy

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CARBOHYDRATE

BLOOD GLUCOSE

Maintaining HomeostasisBalancing within the Normal Range

– Eating balanced meals (abundant complex carbohydrates - including fiber, some protein, and a little fat) helps the body maintain a happy medium between the two extremes

• Fibers and fat slow down the digestion and absorption of carbohydrate enabling glucose to enter the blood gradually

• Dietary protein elicits the secretion of glucagon, whose effects oppose those of insulin

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CARBOHYDRATE

BLOOD GLUCOSE

Glucose Regulation

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CARBOHYDRATE

BLOOD GLUCOSE

Glucose Regulation

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CARBOHYDRATE

BLOOD GLUCOSE

Glucose Regulation

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CARBOHYDRATE

BLOOD GLUCOSE

Glucose Regulation

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Falling outside the Normal RangeIn some people, blood glucose regulation fails

• Diabetes– Insulin Dependent Diabetes Mellitus (IDDM) -- body fails

to produce insulin» Less common» Also known as Type I Diabetes or juvenile-onset diabetes

– Non-Insulin Dependent Diabetes Mellitus (NIDDM) -- cells fail to respond to insulin

» More common» Also known as Type II Diabetes» Is usually milder than IDDM and progresses

more slowly

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Falling outside the Normal Range (continued)

• Hypoglycemia -- an abnormally low blood glucose concentration

– Failures in blood glucose regulation are due to abnormalities in the body’s regulatory system, which alter the way that it responds to foods

– That is, food does not govern the blood glucose level -- the body does

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CARBOHYDRATE

GLYCEMIC EFFECT• Is a measure of the extent to which a food, as

compared to pure glucose, raises the blood glucose concentration and elicits an insulin response

• Refers to:– How quickly glucose is absorbed after a person eats– How high the blood glucose rises– How quickly it returns to normal

• Different foods foods have different effects on blood glucose

• Effect differs depending on whether the food is eaten alone or as a part of a meal

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CARBOHYDRATEGLYCEMIC INDEX OF SELECTED FOODS

Low (best) Moderate (better) High (good)Grains

Pumpernickel bread Sourdough bread White breadPasta Short-grain riceBran cereals Shredded Wheat Cornflakes

WafflesVegetables & Legumes

Soybeans PotatoesLentils CarrotsBaked beans

FruitsPeaches Banana WatermelonApples (& apple juice) PineappleOranges Orange juice

Milk ProductsMilk, Yogurt Ice cream

SweetsChocolate Jelly beans

Soft drinksHoney

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CARBOHYDRATEGLYCEMIC EFFECT

• Pros & Cons– Lowering the glycemic index of of the diet reduces insulin

secretion and improves glucose and lipid metabolism– May help prevent heart disease and diabetes– May help prevent obesity– Prolongs the presence of food in the digestive tract thus providing

greater satiety and diminishes the insulin response– Is complicated to teach– Relatively few foods have had glycemic index determined– Information is neither intuitively apparent nor printed on food

labels– Concern that consumers will adopt a low carbohydrate diet

instead of a low glycemic one

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CARBOHYDRATEAdded Sugars in the US Diet

Soft Drinks33%

Sugars & Candy16%

Sweetened Grains19%

Fruit Drinks10%

Milk Products9%

Cereals4%

Other beverages

4%

Others5%

Soft DrinksSugars & CandySweetened GrainsFruit DrinksMilk ProductsCerealsOther beveragesOthers

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CARBOHYDRATE

HEALTH EFFECTS

Sugar– In the amounts people currently

consume, sugar carries no proven health risk (FDA and National Academy of Sciences Data)

– Obesity -- sugar can contribute to obesity but does not, by itself cause obesity

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CARBOHYDRATE

HEALTH EFFECTS

Sugar (continued)

– Diabetes• Body fatness seems to be more

related to diabetes than diet is• Obesity is a major factor in the

causation of Type II diabetes• Sugar may be a causative factor

only if and when it contributes to obesity

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CARBOHYDRATE

HEALTH EFFECTS

Sugar (continued)

– Heart Disease• Fat, not sugar, is

clearly the major dietary culprit

• Moderate sugar intake does not influence the risk of heart disease

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CARBOHYDRATE

HEALTH EFFECTS

Sugar (continued)

– Hyperactive Behavior in Children• No sugar link confirmed by scientific

research• Sugary foods may replace nutrient-dense

foods causing nutrient deficiencies -- and deficiencies can cause adverse behavior

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CARBOHYDRATE

HEALTH EFFECTS

Sugar (continued)– Dental Caries

• Evidence says there is a relationship --however ANY carbohydrate-containing food can support bacterial growth

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CARBOHYDRATE

HEALTH EFFECTS

Sugar (continued)– Dental Caries

• Bacterial growth produces acid that eats away the enamel causing dental decay

• Level of dental caries seems to be more related to the frequency of sucrose intake than the quantity of sucrose ingested

• Retentive solid forms of sugar appear to be more cariogenic than liquid forms of sugar

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CARBOHYDRATEHEALTH EFFECTS

Complex Carbohydrates– Because diets high in carbohydrates (and low in

concentrated sugar) are also usually low in fat and energy and high in fiber, vitamins and minerals, health benefits area realized in the reduced risk of:

• Obesity• Cancer• Cardiovascular Disease• Diabetes• Dental Caries• Malnutrition

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CARBOHYDRATE

HEALTH EFFECTS

Fiber– Weight Control

• Fiber contributes little energy & promotes a feeling of fullness as it absorbs water

• Diets high in fiber-rich foods can promote weight loss if these foods displace concentrated fats and sweets

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CARBOHYDRATE

HEALTH EFFECTS

Fiber– Constipation, Hemorrhoids

• Some fibers attract water into the digestive tract thereby softening the stool

• Water-insoluble fibers (such as cellulose) contribute undigested residue in the digestive tract thereby enlarging the stool

• Large soft stools ease elimination for the rectal muscles

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Fiber– Appendicitis

• Prevents compaction of the intestinal contents

• Compaction could allow the appendix to become obstructed and permit bacteria to invade and infect it

– Diverticulosis• Stimulates the muscles of the digestive tract• Muscles retain their strength and resist bulging

into pouches known as diverticula

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CARBOHYDRATE

HEALTH EFFECTS

Fiber– Colon Cancer

• Populations consuming high-fiber diets generally have lower rates of colon cancer

• Fiber may prevent colon cancer by diluting, binding, and rapidly removing carcinogens

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CARBOHYDRATE

HEALTH EFFECTSFiber

– Heart Disease• Some fibers bind with bile (the emulisifyer that

assists with cholesterol and fat absorption)• With less bile available, fat and cholesterol

absorption diminishes and blood lipid concentrations decline

• Blood cholesterol levels decline further as the liver makes more bile from cholesterol to replace the bile bound to fiber and excreted

• Products of fiber digestion, once absorbed, also inhibit cholesterol synthesis

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Fiber– Glycemic Response and

Diabetes Control• Some fibers can trap nutrients

and delay their leaving the stomach for the small intestine

• Glucose absorption is thereby slowed, eliciting a moderate insulin response and a moderate rise in blood glucose

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CARBOHYDRATE

HEALTH EFFECTS

Fiber– Negative Health Effects

• May displace energy- and nutrient-dense foods

• When fiber intake is increased too rapidly, intestinal discomfort and gas may be experienced, therefore, increase gradually and be sure fluid intake is adequate

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CARBOHYDRATE

HEALTH EFFECTS

Fiber– Not All Fibers Have Similar Effects

• Wheat bran (composed of mostly insoluble cellulose) has no cholesterol lowering effect while oat bran (soluble) pectin (soluble) do

• Wheat bran is an effective stool-softening fiber

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CARBOHYDRATE

RECOMMENDED INTAKES

SUGARS AND STARCH

DIETARY REFERENCE INTAKE VALUE

• EAR– 100 grams (for brain glucose utilization)

• RDA– 130 grams (for brain glucose utilization)

• Distribution range for healthy diets– 45% - 65% of total Calories

2002 Data

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CARBOHYDRATE

RECOMMENDED INTAKES

FIBER

DIETARY REFERENCE INTAKE VALUE

• AI– Men under 50 -- 38 grams

– Men over 50 -- 30 grams

– Women under 50 -- 25 grams

– Women over 50 -- 21 grams

For greatest protection against coronary heart disease2002 Data

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CARBOHYDRATE

ALTERNATIVES TO SUGAR

ASPARTAME

• Sold as Nutrasweet

• L-alpha-aspartyl-L-phenylalanine methyl ester

• Major consideration is in the use of aspartame in children is in patients with autosomal recessive phenylketonuria

• Seizures, headache, nervousness, dizziness, memory impairment, nausea, temper outbursts, and depression are potential side effects but little controlled documentation exists

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CARBOHYDRATE


Saccharin

• O-toluene sulfonamide derivative

• High consumption in infants is associated with irritability, excessive tone of the skeletal muscles, insomnia, spasms, and strabismus (a deviation of the eye)

• No longer associated with cancer risk in humans

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CARBOHYDRATE

ALTERNATIVES TO SUGARSucralose

• Sold as Splenda and marketed Fall 2000

• A chlorinated sucrose derivative

• Small risk for shrunken thymus glands (up to 40% shrinkage) and enlarged liver and kidneys

• Breaks down into small amounts of 1,6-dichlorofructose (a chemical which has not been adequately tested in humans and might pose cancer or neurological risk

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CARBOHYDRATEALTERNATIVES TO

SUGARStevioside

• Sold as Stevia

• Natural sweetener extracted from the leaves of Stevia rebaudiana

• Little risk for mutagenicity or carcinogenicity

• Suited for both diabetics, and PKU patients, as well as obese persons intending to loose weight by avoiding sugar supplements in the diet

• No allergic reactions to it seem to exist

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CARBOHYDRATE


Sugar Alcohols• Natural sugars with Calories• Examples -- sorbitol, mannitol, xylitol • Slow absorption• 60+ grams per day can be hazardous to

diabetics -- liver converts the excess to simple sugar (a problem if not enough insulin is produced)

• Even with no blood sugar abnormalities, the increase in glucose can hormonally alter insulin and glucagon levels to limit fat release

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CARBOHYDRATE


Tagatose• D-Tagatose

• Is a levo-sugar (left-handed sugar)

• To the tongue, tastes just like regular sugar

• Body cannot digest it

• Ingestion of large amounts may result in GI distress including diarrhea, nausea, and flatulence

• Marketed as Naturlose

1 dnt 200 nutrition for health sciences carbohydrate

Documents

glucose slide

single sugar slide

malt sugar slide

sweetest of sugars

powdered sugars

pairs of single sugars

monosaccharides link

white sugar