Download Carbohydrates

Chapter 2 - Nutritional Needs
Carbohydrates:
• the body’s chief source of energy
• includes starches, sugars and cellulose (fiber)
• most are plant materials produced by photosynthesis
Classified in to three groups based on their molecular structure:
Monosaccharides –
• simplest form of sugar molecule
• cannot be broken down into a simpler sugar form
Disaccharides –
• can be broken down into two monosaccharide molecules
Polysaccharides –
• can be broken down into more than two monosaccharide molecules
Monosaccharides and Disaccharides are simple carbohydrates
Polysaccharides are complex carbohydrates
Simple carbohydrates include six types of sugars.
Single sugar units
• glucose
• fructose
• galactose
Glucose:
• a monosaccharide
• serves as constant and immediate source of energy for all body cells and
Tissues
• occurs naturally in fruits, vegetables, honey, molasses
• body forms glucose during digestion when it breaks down complex
Carbohydrates making it easier for absorption
• often called blood sugar
Fructose:
• a monosaccharide
• sweetest of all sugars
• found in fruits, vegetables, honey, molasses
Sucrose:
• a disaccharide
• ordinary table sugar
• found in sugar beets, sugarcane, maple syrup, molasses, sorghum, corn
Syrup
Carbohydrates
1
Lactose:
• a disaccharide
• milk from mammals
• milk sugar
Maltose:
• a disaccharide
• found in sprouting cereal grains, malted milk, malted cereals
• malt sugar
Disaccharides are broken down during digestion into simpler
monosaccharides.
The body can then absorb them and use them for energy.
Polysaccharides:
• cellulose
• starch
• glycogen
Cellulose:
• fibrous material found in plants
• best sources found in fresh fruit, vegetables, nuts, whole grain, cereals,
dried fruits and vegetables
• humans cannot digest cellulose
• main source of fiber
• provides bulk in the diet
Starch:
• most abundant carbohydrate in the body
• found in roots, seeds, tubers
• must be broken down into glucose before it can be absorbed in the body
Glycogen:
• storage form of carbohydrates in animals
• best sources found in liver and muscle meats
• body must change to glucose before it can be absorbed
Functions of Carbohydrates:
•
•
•
•
furnish the body with energy
help the body digest fats efficiently
make foods more palatable
allow the body to use proteins for growth and maintenance instead of
energy
Carbohydrates
2
Fiber binds to a compound made from cholesterol and carries it out of the body
Functions of carbohydrates rich in fiber:
• may be a cancer preventative
• linked to prevention of heart disease
• helps lower blood cholesterol levels
Sources of Carbohydrates:
Simple carbohydrates:
• sugars, syrups, soft drinks, jams, jellies, candies, and other sweets
Starches:
• breads, cereals, pasta products, rice
• corn, potatoes, dry beans and peas
• whole grain cereal products, fresh fruits and vegetables
Fiber:
• whole grain cereal products, fresh fruits and vegetables
Deficiencies and Excesses
Foods high in carbohydrates are abundant.
Deficiencies in the United States are usually caused by self-prescribed limitations.
A diet low in carbohydrates:
• may cause the body to use protein as an energy source
• could interfere with normal growth and repair of body tissues
• create a chemical imbalance that could be dangerous
• lack of fiber causes constipation
Food energy is measured in calories
It is recommended that most of the calories in your diet come from complex
carbohydrates, especially those with high fiber.
It is recommended that you limit the number of calories consumed from fat.
A diet high in carbohydrates:
Too many simple carbohydrates can be a health concern.
• foods high in sugars – (candy, soft drinks) are low in other nutrients
• deprive the body of other nutrients
• increases the risk of unhealthy weight gain
• bacteria in the mouth thrive, producing acid
Carbohydrates
3
• The acid, erode teeth causing tooth decay and gum disease.
It is recommended that you:
• limit simple carbohydrates between meals
• brush after eating
• floss daily
• get regular dental checkups
Carbohydrates
4