Transcript Unit 12 Useful Facts about Sugars, Starches, and Fiber Key

Unit 12
Useful Facts about
Sugars, Starches, and
Fiber
Key Concepts and Facts
Simple sugars, starches, and dietary
fiber
 Carbohydrates have half the calories
of fat
 Tooth decay is related to high sugar
intake
 Poor diets are related to high sugar
intake
 Fiber benefits health

The Carbohydrates
The Major source of energy for people of the
world
 Main component of staples – bread, pasta,
rice, cassava, and beans
 We Americans consume 50% of total calories
as “carbs.” (Japanese, over 60%)
 Carbohydrate family has three types

– Simple sugars
– Complex carbohydrates (“starch”)
– Fiber (ie Cellulose)
…………………………………………………………………BBC, 03/12/2007
Staple Foods

Food (200 calories) Protein(gm) Carb(gm) Fat(gm)
Fiber(gm)

Whole wheat bread 10
Brown rice
4
Corn tortilla
4
Cassava
3
Potato (with skin)
6.3
Lentils
14
Pintos
13
Soybeans
18
6
3
3
0.2
4
12
10
6







40
42
43
47
55
35
35
17
3
3
4
0.5
0.3
0
1
11


Pork shoulder
14
0
16
?
Cassava
Native to South America
Staple Food of
700 million people
Most important crop
in Africa
Carbohydrate Recommendations

The RDA:
– Minimum amount required to provide adequate
glucose for the brain
– Set at 130 g/day (~ 420 kcalories)

The Range of Healthy Intakes:
– Set at 45% to 65% of energy
– No more than 10% of energy should come from
added refined sugars
Synthesis of Glucose and Starch
4-16
Simple Sugar Facts
Simple sugars are small molecules
 Two types: monosaccharides and disaccharides
 Monosaccharides:

– Glucose (“blood sugar”)
– Fructose (“fruit sugar”)
– Galactose

Disaccharides consist of two linked molecules
– Sucrose is a glucose and a fructose
– Maltose is a glucose and a glucose
– Lactose is a glucose and a galactose
Simple Carbohydrates

Monosaccharides
Simple
Carbohydrates

Disaccharides
4-13
Synthesis of Sucrose
Simple Sugar Facts
Disaccharides are broken into
monosaccharides during digestion
 Only glucose, fructose, and galactose are
absorbed into bloodstream
 High-fructose corn syrup and alcohol sugars
are also simple sugars
 Most simple sugars have a sweet taste

Glucose
Used for energy
 Fructose and galactose converted to glucose
 The liver and muscles store glucose as the
polysaccharide glycogen
 Glycogen: chains of
linked glucose units

Glucose
When body needs energy, glycogen makes
glucose available
 Glucose can also be made from amino acids and
the glycerol of fats
 Cells require glucose as an energy source

Thiamin, Riboflavin, & Niacin
B-1
B-2
B-3


These water-soluble
"B vitamins" are used
in reactions that
capture and release the
energy in
carbohydrates.
Each of these also has
its own unique
functions in the body.
Where’s the Sugar?


Simple sugars are in
fruits and some
vegetables
Besides milk, animal
products have no
sugars
Where’s the Sugar?





Americans consume 84
grams of added sugar per
day, about 17% of the
average caloric intake
Sugar consumption up 23%
in past 30 years
Biggest source for many is
soft drinks
Simple sugars are in fruits
and some vegetables
Besides milk, animal
products have no sugars
Added Sugars




Sugar is added to food during food processing or
preparation
Nutrition labels list total amount of sugar per serving
Nutrition labels contain information on total sugars
per serving and do not distinguish between sugars
naturally present in foods and added sugars
Ingredient labels: All simple sugars must be lumped
together under “sweeteners” followed by a parenthetical
list itemizing each type in order of weight
What’s So Bad about Sugar?





Foods with simple sugars
are poor sources of
nutrients
Simple sugars provide only
calories
Many foods high in sugars
are also high in fat
Diets often insufficient in
vitamins and minerals when
high sugar intake
Sugar causes tooth decay
Baby Bottle Caries
From having bottle
with sugar for hours
every day and
night
Babies need to be off
the bottle when they
have their first birthday

Carbohydrates and Teeth
Sugar and tooth decay related
 Decay declined during WW I and II
 Rebounded when sugar became available
 Highest rates where sugar added to foods
 Simple sugars come from starchy foods
 Some countries have campaigns about
cavity-promoting foods

Sugar Fiction and Fact
Does sugar cause
– violent and criminal behavior?
– produce diabetes?
– cause hyperactivity in children?
 Sugar actually:
– ____________ kids’ activity level
– makes adults sleepy
– reduces appetite in the short-term

Artificial sweetener facts

Why artificial sweeteners?
–
–
–
–

unwanted calories in simple sugars
the connection of sucrose with tooth decay
sugar substitute for people with diabetes
sugar shortages
All provided incentives for developing
sugar substitutes
Artificial sweetener facts





Artificial sweeteners in many prepared foods
None provide many calories, promote tooth
decay or raise blood glucose levels
None provide the taste qualities of sucrose
Do they help with weight loss?
Research results both support and refute a role
for artificial sugars in weight loss
Saccharin
Saccharin was first artificial
sweetener developed, in the
late 1800s
 300 times sweeter than
sucrose
 Helped relieve sugar
shortages during World
Wars I and II

Aspartame




Aspartame is 200 times sweeter than sucrose
Used in 4000 products worldwide, soft drinks,
whipped toppings, jellies, cereals, puddings,
medicines
Products carry a label warning people with
phenylketonuria (PKU) and others with liver
conditions about phenylalanine
PKU folks can’t use phenylalanine so it
accumulates in blood
Is Aspartame Safe?




Safe level defined as 50 mg/kg body weight per
day in U.S. and 40 mg/kg body weight per day in
Canada
U.S. limit equals 20 aspartame-sweetened soft
drinks or 55 desserts per day
Average intake from 2 to 10 mg per day, safely
low
Problems with headaches, dizziness, or anxiety
from small amounts reported by consumers but
not confirmed in studies
Sucralose
Non-caloric sweetener from sucrose, safe and
600 times sweeter than sucrose
 Does not leave a bitter aftertaste
 Known as “Splenda” on product labels
 Used in hot and cold food products, soft drinks,
baked goods, frosting, pudding, and chewing
gum
 Safest choice for children and pregnant women

Complex Carbohydrate Facts
Starches, glycogen, and cellulose are
complex carbohydrates - polysaccharides
 Grains, potatoes, dried beans, and corn
contain starch and cellulose, so are
complex carbohydrate sources
 Little glycogen in animal products
 Remember, all carbohydrates have 4
calories per gram

Complex Carbohydrates

Oligosaccharides

Polysaccharides
4-14
Carbohydrates: Polysaccharides
Starch, cellulose & glycogen
Why Whole Grains?
More protein, vitamins and minerals than refined
grains
 More fiber than refined grain foods
 Reduce the risk of heart disease and some types
of cancer


Bran

Endosperm

Germ
Dietary Fiber Facts




Fiber intake in U.S. below the amount
recommended
People can get recommended amount from wholegrain breads, high-fiber cereal, dried beans and
adequate vegetables and fruits daily
Amounts in food are the same cooked or raw
Fast foods are poor sources of fiber
Types of Fiber
Classification of edible fibers is based on
chemical characteristics
 Natural foods contain insoluble and soluble
fibers
 Fiber is not digested by human digestive
enzymes
 Fibers are also classified as

– dietary fiber (naturally in the food)
– functional fiber (extracted, then added)
– total fiber
Types of Fiber

Soluble Fiber
–
–
–
–
–
–
Slows glucose absorption
Reduces fat and cholesterol absorption
Combine chemically with water
Found naturally in oats, barley, fruits,
Can be natural or added to foods
Soluble fiber supplements may reduce
problems of irritable bowel syndrome: diarrhea,
constipation and abdominal discomfort
Insoluble Fiber
Increases stool bulk, softens stool and
shortens transit time through the intestinal
tract
 Sources include

–
–
–
–
–
Whole grain foods
Wheat and corn bran
Seeds and nuts
Potato skins
Zucchini, cauliflower and green beans
Types of Fiber

Functional fibers –processed fibers-- have
beneficial functions in the body-- most are soluble
fibers so
–
–
–
–


reduce post-meal rises in blood glucose levels
prevent constipation
may decrease symptoms of irritable bowel syndrome
decrease fat and cholesterol absorption
Functional fiber is produced to fortify foods
Psyllium, pectin, gels, and seed and plant gums,
are functional fibers
Fiber: Add it Up

What can you eat in
One day to consume
Recommended fiber?

See page 12-12 and table A-1

Men:
38 gm
Women: 25 gm



Be Cautious
When too much fiber is added too quickly
 High fiber diets cause diarrhea, bloating,
and gas
 Bacteria in intestines use fiber and excrete
gas
 Adding fiber gradually prevents side effects
 Fluid intake should increase with dietary
fiber

We will not cover
Glycemic Index
Glycemic Load
Hypoglycemia
yet
The
End