66
Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Embed Size (px)

Citation preview

Page 1: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Carbohydrates:Simple Sugars and

Complex Chains

Chapter 5

Page 2: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Carbohydrates

• all plant food

• milk

• carbohydrates are not equal– simple carbohydrates– complex carbohydrates

Page 3: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Carbohydrates

• Sugars, starches, and fibers• Major food sources: plants

– Produced during photosynthesis

• Two main carbohydrate types– Simple and complex

Photo © PhotoDisc

Page 4: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Simple Carbohydrates• sugars

– monosaccharides – single sugars– disaccharides – 2 monosaccharides

Page 5: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Simple Sugars: Monosaccharides and Disaccharides

• Simple carbohydrates– Monosaccharides

• Glucose• Fructose• Galactose

– Disaccharides• Sucrose• Lactose• Maltose

Page 6: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Simple Carbs• monosaccharides

– all are 6 carbon hexes• 6 carbons• 12 hydrogens• 6 oxygens• arrangement differs

– accounts for varying sweetness

– glucose, fructose, galactose

Page 7: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Monosaccharides

• Glucose– Is most abundant– Also is called dextrose– Gives food sweet flavor– Provides energy to

body cells• Blood sugar

– Found in fruits, vegetables, honey

© AbleStock

Page 8: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Monosaccharides

• Fructose– Also called levulose or fruit sugar– Tastes the sweetest– Occurs naturally in fruits

and vegetables– Found in fruits, honey,

and corn syrup

© Photodisc

Page 9: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Monosaccharides

• Galactose– Primary sugar in milk and

dairy products– Rarely found naturallyAs a single sugar

- Hardly even taste sweet

© AbleStock

Page 10: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Disaccharides: The Double Sugars

• Two monosaccharides linked

together

• Sucrose, lactose, and maltose

Page 11: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Disaccharides

• pairs of the monosaccharides– glucose is always present– 2nd of the pair could be fructose, galactose or

another glucose– taken apart by hydrolysis– put together by condensation– hydrolysis and condensation occur with all

energy nutrients– maltose, sucrose, lactose

Page 12: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Condensation

• making a disaccharide– chemical reaction linking 2

monosaccharides

Page 13: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Hydrolysis

• breaking a disaccharide– water molecule splits– occurs during digestion

Page 14: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Disaccharides: The Double Sugars

• Sucrose: glucose + fructose– “Table sugar”– Made from sugar cane and sugar beets– Listed as “sugar” on food labels

• Lactose: glucose + galactose– “Milk sugar”– Found in milk and milk products

Page 15: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Sucrose

• fructose and glucose

• tastes sweet– fruit, vegetables,

grains

• table sugar is refined sugarcane and sugar beets

• brown, white, powdered

Page 16: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Lactose

• glucose and galactose

• main carbohydrate in milk– known as milk sugar

Page 17: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Lactose Intolerance

• age, damage, medication, diarrhea, malnutrition

• management requires dietary change– 6 grams (1/2 cup) usually tolerable– take in gradually– hard cheeses & cottage cheese– enzyme drops or tablets

• lactose free diet is extremely difficult to accomplish

Page 18: Carbohydrates: Simple Sugars and Complex Chains Chapter 5
Page 19: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Disaccharides: The Double Sugars

• Maltose: glucose + glucose– Product of starch breakdown– Found in germinating cereal grains– Not abundant

Page 20: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Complex Carbohydrates

• starches and fibers

• polysaccharides– chains of monosaccharides

Page 21: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Complex Carbohydrates

• Chains of two or more sugar molecules– Oligosaccharides– Polysaccharides

• Structural differences• Digestible or nondigestable

Page 22: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Complex Carbohydrates

• Starch– How plants store energy– Found in grains, legumes, and

tubers– Long chains of glucose units

• Amylose—straight chains• Amylopectin—branched chains

– Resistant starch

Page 23: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Starches

• stored in plant cells

• body hydrolyzes plant starch to glucose

Page 24: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Complex Carbohydrates

• Glycogen– Body’s storage form of carbohydrate– Provides glucose when blood glucose

levels get low– Highly branched chains of glucose units– Most stored in our skeletal muscle and liver– Carbohydrate “loading”

Page 25: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Glycogen

• limited in meat and not found in plants– not an important dietary source of

carbohydrate

• BUT– all glucose is stored as glycogen– long chains allow for hydrolysis and release of energy

Page 26: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Complex Carbohydrates

• Fiber– Indigestible chains of monosaccharides– Dietary fiber: found in plants

• Fruits, vegetables, legumes, and whole grains

– Functional fiber: isolated and added to foods

Page 27: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Fiber

• structural parts of plants– found in all plant derived food

• bonds of fibers cannot be broken down during the digestive process– minimal or no energy available

Page 28: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Complex Carbohydrates• Types of fiber

– Oligosaccharides: short chains of monosaccharides• Raffinose, stachyose• Dried beans, peas, lentils, human milk

– Cellulose• In plants: grains, fruit, nuts, vegetables

– Hemicellulose• Variety of monosaccharides

Page 29: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Complex Carbohydrates

– Pectins• All plants, especially fruits

– Gums and cilages• Gel-forming fibers that hold plant cells

together– Lignins

• Nondigestable substances in vegetables and fruit

Page 30: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Fiber types

• cellulose

• pectins

• lignins

• resistant starches– classified as fibers– escape digestion and

absorption

Page 31: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Fiber Characteristics

• soluble fibers, viscous, fermentable– easily digested by bacteria in colon– associated with protection against heart disease

and diabetes• lower cholesterol and glucose levels

– found in legumes and fruits

Page 32: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Fiber

• insoluble and not easily fermented– promote bowel movements– alleviate constipation– found in grains and vegetables

Page 33: Carbohydrates: Simple Sugars and Complex Chains Chapter 5
Page 34: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Carbohydrate Digestion

• break down into glucose– body is able to absorb and use

• large starch molecules– extensive breakdown

• disaccharides– broken once

• monosaccharides– don’t need to be broken down

Page 35: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Carbohydrate Digestion and Absorption

• Digestion: breaking down carbohydrates into simple sugars– Begins in the Mouth – Chewing releases

saliva• Salivary amylase begins digestion of

carbohydrates– Stomach

• No carbohydrate digestion

Page 36: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Carbohydrate Digestion and Absorption

• Digestion– Small intestine

• Pancreatic amylase continues starch digestion

• The brush border enzymes digest disaccharides

• Other digestive enzymes–Maltose, sucrose, and lactase

Page 37: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

• small intestine– majority of carbohydrate digestion takes

place here– pancreatic amylase reduces carbs to

glucose chains or disaccharides– specific enzymes finish the job

• maltase– maltose into 2 glucose

• sucrase– sucrose into glucose and fructose

• lactase– lactose into glucose and galactose

Page 38: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

• large intestine– 1-4 hours for sugars and

starches to be digested– only fibers remain

• attract water, which softens stool

– bacteria ferment some fibers• water, gas, short-chain fatty acids

(used for energy)

Page 39: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Carbohydrate Digestion and Absorption

• Absorption: The small intestine swings into action– End products of carbohydrate digestion

• Glucose• Galactose glucose• Fructose glucose

– Liver stores and releases glucose • To maintain blood glucose levels

Page 40: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Carbohydrate Digestion and Absorption

• Travels with carbohydrate

Page 41: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Carbohydrates

• glucose provides energy for the brain and ½ of energy for muscles and tissues

• glycogen is stored glucose

• glucose is immediate energy

• glycogen is reserve energy

Page 42: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Carbohydrates in Action• Glucose is our primary fuel

– Maintain normal blood glucose levels

– Excess glucose is stored• Using glucose for energy

– Stored glucose as glycogen• Liver• Muscle

Page 43: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Carbohydrate Metabolism• 1/3 of body’s glycogen is stored in liver

– released as glucose to bloodstream

1. eat – intake glucose2. liver condenses extra glucose to glycogen3. blood glucose falls4. liver hydrolyzes glycogen to glucose

Glycogen is bulky, so we store only so much: short term energy supply

Fat is the long term energy supply.

Page 44: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Glucose for Energy

• enzymes break apart glucose – yielding energy

• inadequate supply of carbohydrates– ketone bodies (fat fragments) are an alternate

energy source during starvation– excess ketones can lead to ketosis: imbalance of

acids in body

• minimum of 50 – 100 grams of carbs/day are needed to avoid ketosis

Page 45: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Carbohydrates in Action

• Using glucose for energy– Sparing body protein

• Adequate carbohydrates spare protein– Preventing ketosis

• Ketone bodies–Ketosis dehydration

Page 46: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Glucose Homeostasis

• maintaining an even balance of glucose is controlled by insulin and glucagon– insulin

• moves glucose into the blood

– glucagon• brings glucose out of storage

Page 47: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Carbohydrates in Action

• Regulating blood glucose– Why? To maintain supply for cells– Controlled by hormones

• Insulin–Key

• Glucagon–Breaks down glycogen

• Epinephrine–“Fight or flight” hormone

– Glycemic index

Page 48: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Maintaining Blood Glucose Homeostasis

IntestineWhen a person eats,blood glucose rises.

1

2

Insulin stimulates the uptake of glucose into cells and storageas glycogen in the liver andmuscles. Insulin also stimulatesthe conversion of excessglucose into fat for storage.

3

4

5

6

7 Blood glucose begins torise.

a The stress hormoneepinephrine and other hormonesalso bring glucose out of storage.

GlucoseInsulinGlucagonGlycogen

Glucagon stimulates livercells to break down glycogenand release glucose into theblood.a

Liver

Low blood glucose stimulatesthe pancreas to releaseglucagon into the bloodstream.

As the body's cells useglucose, blood levels decline.

Glucagon

Pancreas

Fat cell

Liver

Muscle

High blood glucose stimulatesthe pancreas to release insulin.

Pancreas

Insulin

Page 49: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Carbohydrates in Action: Regulating Blood Glucose

Page 50: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Carbohydrates in Action

• Diabetes mellitus– Consequences

• Hyperglycemia—persistent high blood glucose levels

–Glucose unable to enter cells–Increased risk of high blood

pressure, heart disease, and kidney disease

–Damage to body proteins and tissues

Page 51: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Carbohydrates in Action

• Diabetes mellitus– Type 1 diabetes: lack of insulin production– Type 2 diabetes: cells are resistant to

insulin• Prediabetes• Insulin resistance

– Gestational diabetes: occurs during pregnancy

Page 52: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Carbohydrates in Action

Page 53: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Carbohydrates in Action

• Diabetes– Best prevention

• Healthful diet–Monitoring and well-balanced meals–The Exchange List for Meal Planning

• Regular exercise

Page 54: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Sugar

• ½ comes from natural sources, ½ from refined and added– sucrose, corn syrup, honey

• excess can lead to nutrient deficiencies and tooth decay– empty calories– sugar and starch break down in the mouth

Page 55: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Sugar

• recommended intake– added sugar = no more than 10% of energy intake

Page 56: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Carbohydrates in Action

• Low blood glucose: hypoglycemia– Symptoms

• Nervousness, irritability, hunger, headache, shakiness, rapid heart rate, and weakness

– Results from• Too much insulin, missed meals, and

vigorous exercise– Reactive hypoglycemia– Fasting hypoglycemia

Page 57: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Carbohydrates in Your Diet

• Recommended carbohydrate intake– RDA = 130 grams per day– AMDR = 45–65% of calories– Daily Value (for 2,000 kcal) = 300 grams– Dietary Guidelines

• Choose carbohydrates wisely• Choose fiber-rich fruits, vegetables, and

whole grains often

Page 58: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Carbohydrates in Your Diet• Choosing carbohydrates

wisely– Increase fruit, vegetables,

whole grains, low-fat milk

• Strategies– Eat peel of fruit/vegetables– Eat legumes– Choose brown rice– Choose high-fiber cereal– Gradually increase and

drink plenty of water!

Page 59: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Starch and Fiber

• diet that includes starch, fiber and natural sugars– whole grains, vegetables, legumes, fruits

• may protect against heart disease and stroke• reduces the risk of type 2 diabetes• enhances the health of the large intestine• can promote weight loss

Page 60: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Carbohydrates in Your Diet

• Moderating sugar intake– Use less added sugar– Limit soft drinks, sugary cereals, and candy– Choose fresh fruits or those canned in water

or juice

Photo © CSquared Studios/PhotoDisc

Page 61: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Carbohydrates in Your Diet

• Nutritive sweeteners– Natural vs. refined– Sugar alcohols

• Non-nutritive sweeteners– Saccharin– Aspartame– Acesulfame K– Sucralose

Page 62: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Artificial Sweeteners

• help keep sugar and energy intake down

• anything we eat has FDA approval– saccharin– aspartame– acesulfame potassium– sucralose– neotame

Page 63: Carbohydrates: Simple Sugars and Complex Chains Chapter 5
Page 64: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Carbohydrates and Health

• Sugar– High sugar intake

may be low in nutrients

– High sugar intake promotes tooth decay

Photo @ PhotoDisc

Page 65: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Sugar Replacers

• sugar alcohols– provide bulk and sweetness

• cookies, gum, candy, jelly

– do contain minimal kcal– low glycemic response

• absorbed slowly

– do not cause dental caries

Page 66: Carbohydrates: Simple Sugars and Complex Chains Chapter 5

Carbohydrates and Health

• Fiber– Possible role in weight control– Better control of blood glucose– Reduced risk of heart disease– Healthier gastrointestinal functioning– Negative effects of excess fiber

• Gradual intake and increased water consumption

• Can bind small amounts of minerals