Download Chapter 4 – Carbohydrates

Chapter 4 – Carbohydrates
* Carbohydrates are the body’s preferred energy source
Carbohydrates provide
calories per gram
SIMPLE CARBOHYDRATES:
 Monosaccharides (Single Sugars)
1. Glucose - energy source for all the body’s cells
2. Fructose - found naturally in fruit and honey
3. Galactose - part of lactose (milk sugar)

Disaccharides (Sugars composed of pairs of monosaccharides)
1. Maltose - glucose + glucose
2. Sucrose - glucose + fructose
3. Lactose - glucose + galactose
COMPLEX CARBOHYDATES (Polysaccharides):
 Glycogen
An animal (human) storage form of carbohydrate. Most is stored in the
, but some is also stored in the muscles and heart.

Starches
Composed of several glucose units linked together.
Food Sources:

Fiber
Found naturally in plant foods, it cannot be broken down by digestion.
Fibers include cellulose, hemicellulose, pectins, gums and mucilages,
lignin, and resistant starches.
Functions:
Recommended Intake: 20-35 grams per day (upper limit is 40 grams)
Food Sources:
DIGESTION OF CARBOHYDRATES:
Carbohydrates digest very rapidly (within 1-4 hours)
Key Digestive Enzymes:
 Amylase – found in saliva, start digestion in the mouth
 Maltase – in small intestine, breaks maltose into 2 glucose units
 Sucrase – in small intestine, breaks sucrose into one glucose and one fructose
 Lactase – in small intestine, breaks lactose into one glucose and one galactose
Lactose Intolerance – inability to digest lactose (milk sugar) because of a deficiency of
lactase. Symptoms include bloating, gas, and diarrhea after consuming dairy products.
ENERGY METABOLISM
Carbohydrates → 100% →
Protein
→
50% →
Fat
→
5% →
Glucose
Glucose
Glucose
Gluconeogenesis – The making of new glucose from a non-carbohydrate source.
Insulin – Hormone secreted by the
for energy
that allows glucose to enter the cells
Glycemic Response – How quickly glucose is absorbed after a person eats, how high
blood glucose rises, and how quickly it returns to normal.
Glycemic Index – A method of classifying foods according to their potential for raising
blood glucose.
SUGAR:
Functions:
 enhances flavor
 supplies texture and color to baked goods
 acts as a bulking agent in ice cream and baked goods
 provides fuel for fermentations, causing bread to rise
 balances the acidity of foods
Health Problems Associated with Sugar:
 Dental Caries
 Nutrient Deficiencies
 Elevated blood glucose levels in people with diabetes
Sugar does NOT cause hyperactivity or behavioral problems
An average person in the U.S. consumes about 30 teaspoons of added sugar a day
Common Sugary Ingredients Include:
 sucrose
 levulose
 corn sweeteners
 corn syrup
 dextrose




high-fructose corn syrup
honey
molasses
etc.
ALTERNATIVE SWEETENERS:
Currently approved by the FDA:
 saccharin
 aspartame
 acesulfame potassium
 sucralose (Splenda)
 neotame
Sugar Replacers (Sugar Alcohols) – Type of sugar not fully absorbed by the body and
has a low glycemic response. May cause gastrointestinal side effects in people sensitive
to it or if too much is consumed. Common sugar alcohols include isomalt, lactitol,
sorbitol, maltitol, mannitol, and zylitol.
Recommended Intakes of Carbohydrates:
45-65% of total calories
RDA =
grams per day (average minimum amount of glucose used by the brain)
To Calculate Your Carbohydrate Needs:
(
) calories needed per day (based on weight & activity)
X .45 (for 45%) =
calories from carbohydrates
(
) calories from carbs ÷ 4 =
minimum grams per day
(
) calories needed per day (based on weight & activity)
X .65 (for 65%) =
calories from carbohydrates
(
) calories from carbs ÷ 4 =
maximum grams per day