Transcript HSC 4572 Selected Portions Chapter 4: Carbohydrates

HSC 4572 Selected Portions
Chapter 4: Carbohydrates
Valerie Schulz, MMSc, RD, LD/N, CDE
Carbs: simple
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Monosaccharides:
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G_________________
F_________________
G_________________
Disaccharides:
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M_________________
S_________________
L_________________
Mono- to Disaccharides – pg 109
Carbs: to complex
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Polysaccharides:
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S____________, found only in ___________
G____________, found only in ___________
F___________, two types:
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Similarity between all three? _____________________
How are first 2 polysaccharides similar?
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S________________
I_________________
__________________________
How are first two different from third?
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____________________________________
Polysaccharides – pg 110
A Close Look at Carbohydrates
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Where do carbohydrates
come from?
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Photosynthesis
Starch: from photosynthesis to the table
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Sun’s energy captured in glucose made by plant
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Starch is a plant’s storage form of glucose
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Used for energy by the plant itself, or
Stored in a fruit or vegetable or seed
Nutritive for humans
Glycogen: Carb storage in animals
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Storage form of glucose in animals, including human
beings.
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Undetectable in meats because glycogen breaks down
rapidly when the animal is slaughtered.
Fiber
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Structural form of glucose in plant leaves, stems, and
seeds.
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Human digestive enzymes cannot break the chemical
bonds holding the sugar units together, i.e. indigestible in
human beings.
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Some is digested by resident bacteria in colon
Need for carbs
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Glucose is a critical energy source for the nervous
system, including the brain.
Fat is not normally used for energy by the nervous
system and brain.
Protein-rich foods are usually expensive and offer no
advantage over carbohydrates
Sugars play vital roles in functioning of body tissues:
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sugars dangling from proteins alter shape and function, like
slippery mucus
sugars bind to the outside of cell membranes, affecting cell-tocell communication
Recommendations for intake of carbs
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1. Total carbs: Dietary Guidelines
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Total carbs: DRI
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At a minimum, ______g carb/d to provide glucose to brain &
prevent ____________________(use of protein for energy)
2. Intakes for added sugars
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Between _____ % and ______% of kcal from carbohydrate
(all the different groups agree, keep it low)
3. Intakes for whole grains and fiber: Dietary Guidelines
2010, USDA food patterns, and DRI
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Reduce refined grains, increase whole grains, increase fruit and
vegetables
Fiber 21g (women 51+) up to 38g (men<50) /day
Fiber actions in the body
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Soluble – actions in body:
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Lower blood cholesterol by binding bile
Slow glucose absorption
Slow transit of food through upper GI
Hold moisture in stools, softening the stool
Increase satiety
Insoluble – actions in the body
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Increase fecal weight, speed passage through colon
Provide bulk, feelings of fullness
How soluble fiber helps lower cholesterol
Probable Health Benefits of Fibers
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Soluble - lower risk of:
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Heart disease
Diabetes
Colon and rectal cancer
Increased satiety may help with weight management
Insoluble – lower risk of:
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Diverticulosis and hemorrhoids
Colon and rectal cancer
Alleviates constipation
Probable Health Benefits of Fibers
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So if there are all these health benefits of fibers, how can
we talk to our clients to encourage them to eat more
fiber?
Should we describe the types of fibers?
Should we mention the total grams per day needed?
Should we bring up food sources?
Probable Health Benefits of Fibers
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For talking to clients, as known from the fiber discussion:
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probably best to discuss a little about health benefits,
but mostly food sources.
Healthy Weight Management
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How can fiber help maintain a healthy weight?
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Whole foods rich in complex carbohydrates
tend to be low in fats and added sugars and
therefore promote weight loss by delivering
less energy per bite.
Fiber provides a feeling of fullness.
Fiber delays hunger because fibers swell as they
absorb water.
Fiber from grains
How much fiber?
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Do you get enough fiber? [fiber logs]
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Can my diet have too much fiber?
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Too much fiber and too little liquids can overwhelm
the digestive system.
Too much purified fiber may displace nutrients
from the diet or cause them to be lost by binding
the nutrients and speeding up transit
Fiber can bind important minerals and carry them
out of the body
Recommendations and Intakes
Consumer Corner:
Refined, Enriched, and
Whole-Grain Bread
Notice that more than 80% of
the wheat kernel is endosperm,
which is the starchy part that
white flour is made from.
Terms to notice: wheat
bread, wheat flour. Most
of your patients/clients do
not understand that all
bread (except glutenfree!) is made from wheat,
and that just because it
says “Wheat” on the label
does not mean it is whole
grain. This will be an
important differentiation
for them.
Also, take a look at white
wheat. Color is very
related to the
phytochemical content of
food.
Consumer Corner:
Refined, Enriched, and
Whole-Grain Bread
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The U.S. Enrichment Act of 1942 was passed by Congress
to prevent deficiencies that developed when people turned
to refined breads.
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Required iron, niacin, thiamin and riboflavin be added to all refined
grain products
Amended in 1996 to include the vitamin folate (folic acid on food
labels)
Just a bit of history to help perspective. When we speed through
Chapters 7 & 8 (vitamins & minerals), there will be a folate chart of
interest…
Digestion and Absorption of Carbohydrate
Shifting gears
now to
glucose use in
the body.
Carbohydrates in Foods to glucose
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Body must have glucose available for its cells at a steady
rate all day, so therefore…
Remind yourself about carbohydrate digestion:
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Mouth/esophagus:
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Stomach:
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Small intestine:
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Large intestine:
Insufficient carbohydrates
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When there is inadequate carbohydrate in the diet, the
body has two problems:
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1. Having no glucose, the body turns to protein [*and fat] to
make some glucose.
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Using protein for energy, to make glucose, also results in excess
ammonia/urea from the nitrogen that was stripped off the protein
(If there was carb avail, would have protein-sparing action of
carbohydrate)
*Fat cannot regenerate enough glucose to feed the brain and prevent
ketosis
2. Without carbohydrate in the diet, fat cannot be used
correctly for energy [‘fat burns in a carb fire’], and the body
converts its fats into ketone bodies.
Insufficient carbohydrate
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Ketosis results when an undesirable high concentration
of ketone bodies accumulate in the blood.
Minimum amount of digestible carbohydrate set by the
DRI committee to adequately feed the brain and reduce
ketosis has been set at 130 grams a day for an averagesized person.
Insulin and Glucagon
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Blood sugar is rising:
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What is secreted? ____________
From where? ______________
Three possible outcomes for glucose
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Stored as ______________ or _______________
Or used as _____________
Blood sugar is falling:
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What is secreted? _____________
From where? ______________
What is acted on? ___________ To release ____________
Storing Glucose as Glycogen
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After a meal, as blood glucose rises, the pancreas releases
insulin, which signals the body’s tissues to take up the
surplus glucose.
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Muscle and liver cells can convert the glucose to glycogen
Brain stores a little glycogen
Storing Glucose as Glycogen
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When blood glucose concentrations drop, a pancreatic
hormone, glucagon, is released.
Glucagon liberates stored glucose from liver glycogen.
Regulation of Blood Glucose
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Regulating blood sugar depends on two pancreatic
hormones:
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Insulin – removes excess glucose from blood to become glycogen
or fat
Glucagon – triggers the breakdown of liver glycogen to free
glucose. *
* Epinephrine also breaks down liver glycogen during emergencies (“fight or
flight” reaction)
The Glycemic Response
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Some carbohydrate-rich foods raise blood glucose and
insulin concentrations higher relative to others.
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Foods can be ranked on a scale known as the glycemic index.
Are Some Carbohydrates “Good” And Others “Bad” For Health?
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Many diet books use the glycemic index as a guide to “good
carbs” and “bad carbs.”
An oversimplification of a complicated situation
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Cola and sugar rank only moderate on the scale
Whole-grain brown rice ranks fairly high
Handling Excess Glucose
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Excess dietary glucose is converted in the liver to:
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Glycogen – (liver and muscles hold a limited amount, 4 to 6 hours
worth)
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Fat – (fat cells may also make fat from excess glucose; unlimited
potential)
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(Have said this more than once; might be important…)
Why Do Some People Have Trouble Digesting Milk?
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As people age, upward of 75 percent of the world’s people
lose the ability to produce the enzyme lactase which
digests lactose.
Almost all mammals lose some of their ability to produce
lactase as they age.
Symptoms of Lactose Intolerance
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Symptoms of lactose intolerance after consuming lactosecontaining products:
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Nausea
Pain
Diarrhea
Excessive gas
(Different from lactose intolerance: Milk allergy is due to the
immune system’s reaction to milk protein. One way to
differentiate this is to ask the person if they tolerate aged
cheeses, like cheddar or swiss. Those cheeses have < 1 g lactose
per ounce, but do have milk protein.)
Milk Tolerance and Strategies
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Many people can tolerate as much as a cup or two of milk a day
Often people overestimate the severity of their lactose
intolerance
Alternatives (to provide calcium) include
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Cheese
Yogurt
Lactose-free milk
Over-the-counter lactase pills and drops
Calcium-fortified juices, canned sardines or salmon with the bones
Plant milks
Food Feature:
Finding the Carbohydrates
in Foods
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For a 2,000-calorie diet
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Carbohydrates should provide 45% to 65% of calories
225 to 325 grams each day
Terms of interest on the following slide:
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Brown sugar: not as many nutrients as we might think…
Dextrose: IVs are labeled D 5 or D 10 (5 or 10% dextrose)
Honey: mainly monosaccharides – quickly affects blood sugar
Maple sugar: concentrate of maple syrup. Real maple syrup has a
higher potassium content than the concocted store brands. Keep that
in mind when we get to renal disease.
Raw sugar: (buyer beware…)
Food Feature:
Finding the Carbohydrates
in Foods
Food Feature:
Finding the Carbohydrates
in Foods
Controversy:
Sugar and Alternative
Sweeteners: Are They Bad
For You?
Does Sugar Cause Obesity?
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Any weight gain associated with sugars may result not so
much with the chemistry of the carbohydrate itself, but with
how it is used in the diet.
Most people choose far too may servings of sweet foods
and beverages (juices/sodas), while ignoring the whole
carbohydrate sources, such as fruits, vegetables, and whole
grains.
Does Sugar Cause Type 2 Diabetes?
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Added sugars alone are not culpable in type 2 diabetes
causation.
Added sugars can easily provide excess calories, however,
and type 2 diabetes risk rises with body weight.
Does Sugar Cause Dental Caries?
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Total sugar does play a major role in the prevalence of
dental caries.
Evidence Concerning Sugar Alcohols
Evidence Concerning Sugar Alcohols
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Do not contribute to dental caries because not metabolized
by oral bacteria
Low glycemic index so useful for people with diabetes
Side effects from ingesting large amounts
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Gas
Abdominal discomfort
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Diarrhea
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Evidence Concerning Artificial Sweeteners
Terms to notice:
ADI, acesulfame K,
aspartame (Equal –
blue), saccharin
(Sweet ‘N Low –
pink), stevia (Truvia,
PurVia - green),
and sucralose
(Splenda – yellow)
Evidence Concerning Artificial Sweeteners
Personal Strategies For Using Artificial Sweeteners
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Current evidence indicates that moderate intakes of
artificial sweeteners pose no health risks.
Artificial sweeteners may not be a magic bullet in fighting
overweight, but they probably do not hinder weight-loss
efforts either, and they are safer for teeth than carbohydrate
sweeteners.
There is much controversy over artificial sweeteners; as health
professionals, be sure that what you say to your patients is based
on scientific fact.