chapter 4 the carbohydrates: sugar, starch, and fiber

Chapter 4

The Carbohydrates: Sugar, Starch,

and Fiber

Ask Yourself

True or False?1. Fruit sugar (fructose) is less fattening than

table sugar (sucrose).2. Foods high in complex carbohydrate (starch

and fiber) are good choices when you are trying to lose weight.

3. People with diabetes should never eat sugar.4. The primary role of dietary fiber is to provide

energy.5. The brain demands the sugar glucose to fuel

its activities.

Ask Yourself

6. Honey and refined sugar are the same as far as the body is concerned.

7. Of all the components of foods that increase one’s risk of diseases, sugars are probably the biggest troublemakers.

8. Breads that are brown in color have more fiber than white bread.

9. Some foods labeled sugar-free actually contain calorie-bearing sugars.

10. Artificial sweeteners are safe to use in moderation.

The Body’s Need for Carbohydrates

• The primary role of carbohydrates is to provide the body with energy (calories).

• Carbohydrates are the preferred fuel for the brain and nervous system.

• Carbohydrates are the ideal fuel compared to other alternatives:Less expensive than protein.High-fat diets are associated with chronic

disease.

Carbohydrate Basics

Carbohydrates Compounds made of single sugars or multiples of

them and composed of carbon, hydrogen, and oxygen atoms. carbo = carbon (C) hydrate = water (H2O)

Complex carbohydratesLong chains of sugars (glucose) arranged as starch or fiber. Also called polysaccharides. poly = many saccharides = sugar unit

Simple carbohydrates (sugars)Single sugars (monosaccharides) and the pairs of sugars (disaccharides) linked together.

Carbohydrate Basics

• Carbohydrate-rich foods are obtained almost exclusively from plants.

Milk is the only animal-derived food that contains significant carbohydrate.

• All carbohydrates are composed of single sugars, alone or in various combinations.

Simple Carbohydrates

• Glucose is made of water and carbon dioxide.

Plants use energy from the sun to synthesize it.

• The atoms in a glucose molecule can be rearranged by plants to form fructose, too.


• Single Sugars - Monosaccharides:Glucose The building block of carbohydrate; a single sugar

used in both plant and animal tissues as quick energy. A single sugar is known as a monosaccharide.• mono = one

Fructose Fruit sugar—the sweetest of the single sugars. Galactose: Another single sugar that occurs bonded to

glucose in the sugar of milk.


• Double Sugars - Disaccharides:Sucrose: A double sugar composed of glucose and

fructose. A double sugar is known as a disaccharide.• di = two

Maltose A double sugar composed of two glucose units.Lactose A double sugar composed of glucose and

galactose; commonly known as milk sugar.


Added Sugars:• Sugar cane and sugar

beets are purified to make sucrose.

• Food examples include white (table) sugar, brown sugar, powdered sugar.

• Sucrose is common in sweets.A sampling of foods

providing added sugars to the diet.


• Enzymes

Protein catalysts. A catalyst facilitates a chemical reaction without itself being altered in the process.

Utilized in the brewing process to break down starch in barley and wheat into maltose

• Lactose intolerance

Inability to digest lactose as a result of a lack of the necessary enzyme lactase.

Symptoms include nausea, abdominal pain, diarrhea, or excessive gas that occurs anywhere from 15 minutes to a couple of hours after consuming milk or milk products.

Complex Carbohydrates: Starch

Complex carbohydrates include starch and fiber. All starchy foods are plant foods.•Starch A plant polysaccharide composed of hundreds of glucose molecules, digestible by human beings.•Polysaccharide A long chain of 10 or more glucose molecules linked together in straight or branched chains; another term for complex carbohydrates.


Sources of starch include:

• Seeds such as grains, peas and beans.

• Legumes including dried beans, lentils and soybeans.

• Root vegetables (yams) and tubers (potatoes).


• Most societies have a staple grain that provides most of the people’s food energy.

• Staple grain A grain used frequently or daily in the

diet. Examples include: Corn in Mexico Rice in Asia Wheat in Canada, Europe and USA Millet, rye, barley, and oats


• Refined: Refers to the process by which the coarse parts of

food products are removed. • Enriched Refers to a process by which the B vitamins

thiamin, riboflavin, niacin, folic acid, and the mineral iron are added to refined grains and grain products at levels specified by law.

• Fortified foods Foods to which nutrients have been added.

Typically, commonly eaten foods are chosen for fortification with added nutrients to help prevent a deficiency of a nutrient (iodized salt, milk with vitamin D) or to reduce the risk of chronic disease (juices with added calcium).

Complex Carbohydrate: Starch

A Whole Grain:• Germ The nutrient-rich and fat-dense

inner part of a whole grain.• Endosperm Provides energy; contains

starch grains embedded in a protein matrix.

• Bran Fibrous protective covering of

a whole grain; source of fiber, B vitamins, and trace minerals.

• Husk (Chaff) The outer, inedible covering of

a grain.


• Whole grain Refers to a grain that is milled in its entirety (all but

the husk), not refined. Whole grains include wheat, corn, rice, rye, oats, barley,

amaranth, buckwheat, sorghum, and millet; two others—bulgur and couscous—are processed from wheat grains.

Complex Carbohydrates: Fiber

• Fiber:

The indigestible residues of food, composed mostly of polysaccharides. The best known fibers are cellulose, hemicellulose, pectin, and gums.

Comes from the supporting structures of plants: leaves, stems and seeds.

Cannot be broken down by human digestive enzymes although some may be broken down by bacteria residing in the digestive tract.

Fiber has few if any calories because it is not digested.

Complex Carbohydrates: Fiber

• Insoluble fiber• Includes the fiber

types called cellulose, hemicellulose, and lignin.

• Insoluble fibers do not dissolve in water.

• Soluble fiber • Includes the fiber

types called pectin, gums, mucilages, some hemicelluloses, and algal substances (for example, carageenan).

• Soluble fibers either dissolve or swell when placed in water.

Insoluble fiber:• Holds water in the

colon and increases bulk to the stool.

• Stimulates muscles and helps maintain health and tone.

Soluble fiber:• Binds cholesterol

compounds and may lower blood cholesterol.

• Improves body’s handling of glucose.

Foods rich in insoluble fiber:Bran

Brown rice

Green beans

Green peas

Many veggies

Nuts

Rice

Seeds

Skins/peels

Wheat bran

Whole-grain products

Foods rich in soluble fiber:Barley

Broccoli

Carrots

Corn

Fruits

Legumes

Oat bran

Oats

Potatoes

Rye

We are advised to increase our intakes of complex carbohydrates. Choose plenty of whole foods like this…

…and fewer foods like these—foods that no

longer resemble their original farm-grown

products.

Choosing Carbohydrates

• Whole food

A food that is altered as little as possible from the plant or animal tissue from which it was taken—such as milk, oats, potatoes, or apples.

The more a food resembles the original, farm-grown product, the more nutritious it is likely to be.

Fiber in the Diet

• Diets high in fruits, vegetables and legumes will provide high fiber

• Too much fiber can cause dehydration, intestinal discomfort and limit absorption of iron and other nutrients


Added Sugars: Use Discretion• Reduce the intake of calories from

added sugars. (Dietary Guidelines).Added Sugar Sugars and other caloric sweeteners

that are added to foods during processing or preparation. Added sugars do not include naturally occurring sugars that are found in milk and fruit.


• Choose most often the naturally occurring sugars (DRI).

• For those who meet their nutrient needs, maintain a “healthy body weight” and still need additional calories--maximum intake = 25% or less for added sugars (DRI).


• Small amounts of added sugars allowed within MyPlate calorie allowance:

3 tsp. for 1,600 calories 5 tsp. for 1,800 calories 8 tsp. for 2,000 calories 9 tsp. for 2,200 calories 12 tsp. for 2,400 calories

Consistently build your diet using nutrient-dense foods, low in added sugars.

Whole Grains for Health

• Incorporate whole grains into your diet.

1.Count to 32.Keep it varied3.Check the label

• Breakfast: Try a higher-fiber grain: oatmeal, whole-grain muffin, or whole-grain cereal

• Whole grains are low in fat and added sugars• Baking recipes: Substitute whole-grain flour for

1/4 of all-purpose flour• Make a fiber-rich snack mix from whole grain

cereals, popcorn, and nuts• Try whole-wheat pasta, rice, and breads • Combine whole grains in mixed dishes

Make Half Your Grains Whole

How the Body Handles Carbohydrates

• Glucose is the basic carbohydrate unit that each cell uses for energy.

• The task of the digestive system is to disassemble lactose, sucrose and starch into single sugars so they can be absorbed into the blood.

• Digestive system The body system composed of organs and glands

associated with the ingestion and processing of food for absorption of nutrients into the body.

• Digestion The process by which foods are broken down into

smaller absorbable products.• Absorption The passage of nutrients or substances into cells or

tissues; nutrients pass into intestinal cells after digestion and then into the circulatory system (for example, into the bloodstream).


• If the blood delivers more glucose than the cells need, glycogen will be built.Glycogen

A polysaccharide composed of chains of glucose, manufactured in the body and stored in liver and muscle.

• As a storage form of glucose, liver glycogen can be broken down by the liver to maintain a constant blood glucose level when carbohydrate intake is inadequate.


4. Most fiber passes intact throughthe digestive tract through thelarge intestine, and is eventuallyexcreted with the feces. Somefiber is digested by bacteria in thelarge intestine.

3. These simple sugars are thenabsorbed into the blood and travel to the liver; the liver regulates the amount of glucose circulating inthe blood in response to thehormones insulin and glucagon.

1. Carbohydrate digestion begins in the mouth. The salivary glands secrete a watery fluid into the mouth to moisten the food. An enzyme begins digestion by splitting starch into smaller polysaccharides and maltose. This digestion continues after the food is swallowed until stomach acid and enzymes start to digest the salivary enzymes.

2. The pancreas produces carbohydrate digestingenzymes and releases themthrough the common bile duct into the small intestine. These enzymes split polysaccharides into disaccharides. Then enzymes on the surface of the cells of the small intestine break these into simple sugars (monosaccharides). Absorption of the monosaccharides takes place in the small intestine.

Largeintestine

Smallintestine

Pancreas

Stomach

Liver

Salivaryglands

Gallbladder

When a person eats, blood glucose rises. High blood glucose stimulates the pancreas to release insulin. Insulin serves as a key for entrance of blood glucose into cells. Liver and muscle cells store the glucose as glycogen. Excess glucose can also be stored as fat.

Later, when blood glucose is low, the pancreas releases glucagon, which serves as the key for the liver to break down stored glycogen into glucose and release it into the blood to raise blood glucose levels.

Elevatedblood

glucose

Normalblood

glucoserange

Lowblood

glucose

70 mg/dL

110 mg/dL*Digestivetract

Bodycells

Glucose

Glucose

Bloodstream

Bloodstream

Glucagon

Pancreas

Pancreas

Liver

Glucose

Glycogen

Bodycells

Insulin

• Insulin: A hormone secreted by the pancreas in

response to high blood glucose levels; it assists cells in drawing glucose from the blood.

• Glucagon A hormone released by the pancreas that

signals the liver to release glucose into the bloodstream.


Carbohydrates--Friend or Foe?

• Glycemic index (GI) A scale that ranks carbohydrate-containing foods

by how much they raise blood glucose levels compared to a standard food such as glucose or white bread. The glycemic load (GL) is a measure of the extent to which blood glucose is raised by a given amount of carbohydrate-containing food.

• Glycemic effect The effect of food on a person’s blood glucose and

insulin response – how fast and high the blood glucose rises and how quickly the body responds by normalizing.

High glycemic index foods:

French, white, other soft breads/bagels

Rice (medium-grain)

Certain cereals (Cheerios, Corn Flakes, Rice Krispies)

Waffles

Mashed potatoes

Honey, regular soft drinks, jelly beans

Pretzels

Intermediate glycemic index foods:

Watermelon

Cream of Wheat, instant oatmeal, Shredded Wheat

Sourdough & rye breads

Banana, pineapple, orange juice

Ice cream

Popcorn

Raisins

Low glycemic index foods:

Whole-grain, heavy breads

Rice (long-grain)

Bran cereals, toasted Muesli cereal, whole oats

Apples, oranges, peaches

Baked beans, lentils, other legumes

Carrots

Milk, yogurt

Sweet potatoes

Tomato soup

Hypoglycemia & Diabetes

• Hypoglycemia An abnormally low blood glucose concentration

—below 60 to 70 mg/100 mL.• Ketosis Abnormal amounts of ketone bodies in the blood

and urine; ketone bodies are produced from the incomplete breakdown of fat when glucose is unavailable for the brain and nerve cells.

• Hyperglycemia An abnormally high blood glucose

concentration, often a symptom of diabetes.

Diabetes

• Diabetes A disorder (technically termed diabetes

mellitus) characterized by insufficiency or relative ineffectiveness of insulin, which renders a person unable to regulate the blood glucose level normally.Type 1 diabetesType 2 diabetesGestational diabetes

Prevalence of Diagnosed Diabetes by State

Sugar and Health

• Research studies have not shown a direct link between sugar and obesity, diabetes, heart disease, hyperactivity in children or criminal behavior.

• Does show a link with tooth decay• Diluted naturally occurring sugars found in milk and

fruits should not be confused with concentrated, refined sugar foods, such as table sugar, honey, and corn syrup. These concentrated sweets should be used in moderation, so as not to displace needed nutrients.

• Empty-calorie foods A phrase used to indicate that a food supplies calories

but negligible nutrients.

Keeping a Healthy Smile

• Dental caries Decay of the teeth, or cavities.• Dental plaque A colorless film, consisting of bacteria and their by-

products, that is constantly forming on the teeth.• Periodontal disease Inflammation or degeneration of the tissues that

surround and support the teeth.• Nursing bottle syndrome Decay of all the upper and sometimes the back

lower teeth that occurs in infants given carbohydrate-containing fluids when they sleep, or to carry around and sip all day.


• The Dietary Guidelines for Americans recommend that you

“reduce the intake of calories from added sugars”

Bacteria living in the mouth feed on sugar found in foods & release an acid that can eat away at tooth enamel & result in a cavity.

Dental caries: decay of the teeth, or cavities.

HOW DID YOU DO? The more often you choose the items listed above, the

higher your diet is likely to be in sugars. You may need to cut back on sugar-containing foods, especially those you checked as “3 to 5 times a week” or more. This does not mean totally eliminating these foods from your diet.

Carbohydrate Consumption

Fiber…

Check Your Diet for Fiber

Sweet Talk--Alternatives to Sugar

chapter 4 the carbohydrates: sugar, starch, and fiber

Documents

sugar glucose

sugar of milk

milk sugar

brown sugar

powdered sugar

sugar cane

sugar beets

refined sugar