ch 4 carbs derived nutrients Flashcards
carbohydrates
carbohydrates
- 1 of the 3 macronutrients
- an important energy source especially for nerve cells
- composed of the atoms: CARBON, HYDROGEN, OXYGEN
- good sources include FRUITS, VEGETABLES, GRAINS
disaccharides
lactose is made of what monosaccharides
glucose + galactose
also called milk sugar
disaccarides
maltose is what made of what monosaccharides
glucose + glucose
maltose molecules join in food to form starch molecules
disaccharides
sucrose is what made of what monosaccharides
glucose + fructose
found in sugar cane, sugar beets, honey
complex carbs: starch
plants store glucose as
polysaccharides in the form of starch
complex carbs: starch
our cells cannot use complex
starch molecules exactly as they occur in plants
complex carbs: starch
we digest (break down) starch into
glucose
complex carbs: starch
grains, legumes, and tubers are good sources of
dietary starch
complex carbs: glycogen
animals store glucose as
glycogen
complex carbs: glycogen
stored in our bodies in the
liver and muscles
complex carbs: glycogen
not found in
food and therefore not a dietary source of carb
complex carbs: fiber
dietary fiber
the nondigestable part of plants
complex carbs: fiber
functional fiber
nondigestable form of carb with known health benefits
extracted from plants and added to foods
ex. cellulose, guar gum, pectin, psyllium
complex carbs: fiber
total fiber
dietary + functional fiber
complex carbs
dietary fiber is also classified by
solubility
complex carbs: fiber
soluble fiber
- dissolves in water
- viscous and fermentable
- easily digested by bacteria in the colon
complex carbs: soluble fiber
found in
- citrus fruits
- berries
- oats
- beans
complex carbs: soluble fiber
reduces risk of
- cardiovascular disease
- type 2 diabetes
by lowering blood cholesterol and glucose levels
complex carbs: fiber
insoluble fiber geneally does not
dissolve in water
complex carbs: insoluble fiber
found in
whole grains (wheat, rye, brown rice)
complex carbs: insoluble fiber
promote
- regular bowel movements
- alleviate constipation
- reduce risk of diverticulosis
why do we need carbs?
energy
- fuel daily activity
- fuel exercise
- help preserve protein for other uses
why? when the diet does not provide enough carbs, the process of gluconeogenesis converts proteins in blood and tissue into glucose
why do we need carbs? – energy
each gram of carb equals to
4 kcal
why do we need carbs? – energy
red blood cells rely ONLY on
glucose for their energy supply
why do we need carbs? – energy
both carbs and fats supply energy for
daily activities
why do we need carbs? – energy
glucose is especially important for
energy in exercise
why do we need carbs? – energy
sufficient energy intake from carbs prevents
production of ketones as an alternate energy source
why do we need carbs? – energy
excessive ketones can result in
high blood acidity and ketoacidosis
why do we need carbs? – energy
high blood acidity damages
body tissues
why do we need carbs? – fiber
may reduce the risk of
colon cancer
heart disease
why do we need carbs? – fiber
promotes bowl health by helping to prevent
hemorrhoids and constipation
why do we need carbs? – fiber
may enhance
weight loss
why do we need carbs? – fiber
may lower the risk of
type 2 diabetes
why do we need carbs? – fiber
reduces the risk of
diverticulosis
why do we need carbs?– energy
energy fuels what
- daily activity
- exercise
why do we need carbs?– energy
help preserve protein for other
uses
* when the diet does not provide enough carbs, the process of gluconeogenesis converts proteins in blood and tissue into glucose
fiber may help decrease blood cholesterol–high fiber diet
- liver synthesizes bile using cholesterol
- bile stored in gallbladder
- bile is secreted into intestine to aid in the digestion of fat
4a. fiber binds to bile and both are excreted in the feces
4b. less cholesterol is reabsorbed from the remaining bile
4c. blood levels of cholesterol are reduced
fiber may help decrease blood cholesterol–low fiber diet
- liver synthesizes bile using cholesterol
- bile is stored in gallbladder
- bile is secreted into intestine to aid in the digestion of fat
4b. less fiber is present to bind bile, so less bile is excreted in the feces
4b. more cholesterol is reabsorbed from the remaining bile
4b. blood levels of cholesterol are elevated
digestion of carbs
most chemical digestion of carbs occurs in the
small intestine
digestion of carbs
pancreatic amylase
- enzyme produced in the pancreas and secreted into the small intestine
- enzymatically digests starch to maltose
digestion of carbs
additional enzymes secreted by cells that line the small intestine (mucosal cells) digest
disaccharides to monosaccharides
* these ensymes include maltose, sucrase, lactase
digestion of carbs
monosaccharides are absorbed into the cells lining the
small intestine and then enter the blood stream
digestion of carbs
most monosaccarides are converted to
glucose by the liver
digestion of carbs
glucose is released into the bloodstream to
provide immediate energy
digestion of carbs
excess glucose is converted to
glycogen and stored in the liver and muscles
process of glycogenesis
- small intestine
dietary carbs from stomach delivered to small intestine
process of glycogenesis
- liver
glucose and other monosaccharides transported to liver
blood levels of glucose maintained for brain and other body cells
process of glycogenesis
- muscles
glucose transported to muscle
regulation of blood glucose–insulin
a hormone secreted by the
pancreas
regulation of blood glucose–insulin
transported in our blood throughout the
body
regulation of blood glucose–insulin
helps transport glucose from the blood into
cells
regulation of blood glucose–insulin
stimulates the liver and muscles to take up
glucose and convert it to glycogen
regulation of blood glucose–glucagon
another hormone secreted by the
pancreas
regulation of blood glucose–glucagon
stimulates the breakdown of glycogen to
glucose to make glucose available to cells of the body
regulation of blood glucose–glucagon
stimulates gluconeogenesis
the production of “new” glucose from amino acids
regulation of blood glucose
fructose does not stimulate the release of
insulin
* fructose is metabolized differently than glucose
* absorbed further down in the small intestine
regulation of blood glucose
glycemic index
a measure of a food’s ability to raise blood glucose levels
regulation of blood glucose– glycemic index
foods with a low glycemic index cause low to moderate
fluctuations in blood glucose
regulation of blood glucose
glycemic load
amount of carb in a food multiplied by its glycemic index
* considered a MORE USEFUL tool than glycemic index
regulation of blood glucose
foods and meals with a lower glycemic load
- are better for people with diabetes
- are generally higher in fiber
- may reduce the risk of heart disease and colon cancer
- are associated with a reduced risk of prostate cancer
how much carb should we eat?
the recommended dietary allowance (RDA) for carb is
130 g per day just to supply the brain with glucose
how much carb should we eat?
45%-65% of daily calorie intake should be in the form of
carbs
how much carb should we eat?
focus on foods high in ____ low in _____
fiber
added sugars
how much carb should we eat?
most americans eat too much
added sugar
how much carb should we eat?– added sugars
sugars are added to foods during
processing or preparation
how much carb should we eat?– added sugars
most common source is
soft drinks
how much carb should we eat?– added sugars
typical sources are
- cookies
- candy
- fruit drinks
how much carb should we eat?– added sugars
unexpected sources include
- peanut butter
- flavored rice mixes
- salad dressing
how much carb should we eat?– added sugars
added sugars are not chemically different from naturally occurring
sugars
BUT HAVE FEWER VITAMINS
how much carb should we eat? sugars
sugars are blamed for many
health problems
how much carb should we eat? sugars
can cause dental
problems and tooth decay
how much carb should we eat? sugars
no proven association with childhood
hyperactivity
long-term effects not known
how much carb should we eat? sugars
associated with increased ________ and decreased _________—-
“bad cholesterol”
“good cholesterol”
how much carb should we eat? sugars
associated with a higher risk of
diabetes
obesity
how much carbs should we eat
most americans eat too little
fiber-rich carbs
how much carbs should we eat
the adequate intake (AI) of fiber is
14g per 1000 kcal in the diet daily
or 25g for women; 38g for men
how much carbs should we eat
whole-grain foods
(grains, vegetables, fruits, nuts, legumes)
are much more healthful
sources than foods with added sugar or fiber
* whole grains are kernels that retain the bran, endosperm, germ
alternative sweetners
nutritive sweetners
- contain 4 kcal energy per gram
- sucrose, fructose, honey, brown sugar
alternative sweetners
sugar alcohols
- contain 2-3 kcal energy per gram
- have the benefit of a decreased glycemic response and decreased risk of dental caries
alternative sweetners
non-nutritive (alternate) sweetners
- provide little or no energy
- developed to sweeten food without the usual risks
alternative sweetners
no acceptable daily intake (ADI) has been set for
saccharin (sweet n’ low)
but it has been removed from the list of cancer causing agents
alternative sweetners
ADIs have been established for
- acesulfame (sweet one, sunette)
- aspartame (equal)
- sucralose (splenda)
in depth: diabetes
inability to regualte blood
glucose levels
in depth: diabetes
hyperglycemia
in which glucose levels are higher than normal— becomes chronic
in depth: diabetes
there are 3 types
- type 1 diabetes
- type 2 diabetes
- gestational diabetes
in depth: diabetes
uncontrolled diabetes can cause
- infections
- nerve damage
- kidney damage
- blindness
- seizures
- stroke
- cardiovascular disease
CAN BE FATAL
in depth: diabetes
type 1 diabetes
- Accounts for about 5% of all cases
- Body does not produce enough insulin
- Creates high blood sugar (glucose) levels
- Key warning sign is frequent urination
- May lead to ketoacidosis, coma, and death
- Classified as an autoimmune disease
- Most frequently diagnosed in adolescents
- Has a genetic link
in depth: diabetes
type 2 diabetes
Accounts for 90–95% of cases
* Develops progressively over time
* Body cells become insensitive or
unresponsive to insulin
* Obesity is most common trigger
* Variations include insulin resistance, impaired
fasting glucose, and prediabetes
* Eventually the pancreas may become unable
to produce any insulin
*
Diabetes Testing and Diagnosis
Three blood tests can be used to diagnose
diabetes
- Fasting plasma glucose (FPG)
- Oral glucose tolerance (OGT)
- Glycosylated hemoglobin test (HbA1c
In Depth: Diabetes
Who is at risk?
- Obesity, genetics, physical inactivity, and poor
diet increase overall risk - Metabolic syndrome (high waist
circumference, high blood pressure, high
blood lipids and glucose) increases risk of
type 2 diabetes - Increased age increases risk, but younger
people and even children are now commonly
diagnosed
In Depth: Diabetes
Prevention and control
- Eat a healthful diet, get daily exercise, keep a
healthful body weight - Limit intake of added sugars
- Choose fiber-rich foods like whole grains
- Limit consumption of red meat and processed
meat
In Depth: Diabetes
Prevention and control continued
- Avoid alcoholic beverages, which can cause
hypoglycemia - Healthful lifestyle choices can prevent or
delay onset of type 2 diabetes - Oral medications and/or insulin injections
may be required once diabetes has been
diagnosed
