Unit 12Useful 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 40 3 6 Brown rice 4 42 3 3 Corn tortilla 4 43 4 3 Cassava 3 47 0.5 0.2 Potato (with skin) 6.3 55 0.3 4 Lentils 14 35 0 12 Pintos 13 35 1 10 Soybeans 18 17 11 6
Pork shoulder 14 0 16 ?
Cassava
Native to South America
Staple Food of700 million people
Most important cropin 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, & NiacinB-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 whole-
grain 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
TheEnd