Unit 5- Macronutrients - Carbohydrates Flashcards
Carbohydrates
• Monosaccharides (seldom found free in nature)
– Glucose
– Fructose
– Galactose
• Disaccharides
– Sucrose
– Lactose
– Maltose
• Oligosaccharides (Water-soluble, often sweet)
– ______ (Trisaccharide: galactose, fructose, & glucose) Found in beans, cabbage,
brussels sprouts, broccoli, asparagus, other vegetables, and whole grains
– ________ (Tetrasaccharide: 2 galactose, glucose, & fructose) Found in numerous
vegetables (e.g. green beans, soybeans and other beans)
• Polysaccharides
– Amylose
– Amylopectin
– Resistant starch
– Dextrins
– Glycogen (animal carbohydrate)
Raffinose
Stachyose
Types of Carbs and Food Sources
Dietary Fibers: intrinsic and intact in natural foods. Mixture of un-digestible polysaccharides & NON-carbohydrate compounds
– ________ = β1——>4 glucose units
– _______ =Linear D-xylose w/ side chains
Cellulose
Hemicellulose
Dietary Fibers: intrinsic and intact in natural foods. Mixture of un-digestible polysaccharides & NON-carbohydrate compounds
_____ = Soluble polymer of galacturonic acid
______ = Methoxy-phenol polymers
Pectin
Lignin
Dietary Fibers: intrinsic and intact in natural foods. Mixture of un-digestible polysaccharides & NON-carbohydrate compounds
_____ = Sugar acid polymer and galactan mix
__________ = Extensin is the major form
Mucilage
Glycoprotein
Dietary Fibers: intrinsic and intact in natural foods. Mixture of un-digestible polysaccharides & NON-carbohydrate compounds
___ _____ = Inositol hexaphosphate, chelating
______ = Esters of fatty acids and alcohols
Phytic acid
Waxes
Role of Fiber in Digestion and Absorption
• Varies based on its solubility
• Insoluble fiber _______ stool volume and
________ gastrointestinal (GI) transit time
• Soluble fiber SLOWS GI transit time, BINDS
cholesterol and minerals, and decreases
nutrient absorption
• Fermented into short-chain fatty acids
• Absorb water, fats, bile acids and cholesterol = Lower blood glucose, TGs, cholesterol
• Provide a bulk effect to reduce food intake
• Enhance excretion of gas
• Act as ‘__________’ to promote beneficial
intestinal bacteria (probiotics)
• Some of the best are _______ (polymers of
fructose, eg inulin), found in artichoke, onions,
asparagus, dandelion root
increases
decreases
prebiotic
fructans
Role of Fiber in Digestion and Absorption
AI =
___ g/day for men
___ g/day for women
38
25
Dietary Fiber
• Although not digested or absorbed, they can prevent or ameliorate the following conditions: – Constipation – Diarrhea – Diverticulosis / diverticulitis* – Glucose intolerance – Hypercholesterolemia – Colon cancer – CHD – Obesity
KNOW
Digestion, Absorption and Transport
Digestion:
1–Monosaccharides: do NOT require ____
2–Disaccharides: digested by _____ enzymes
digestion
intestinal
Sucrose = glucose + fructose/ENZYME =??? Lactose = glucose + galactose/ENZYME =??? Maltose = glucose + glucose/ENZYME =?? Isomaltose = glucose + glucose/ENZYME =?
Starches and Glycogen: digested to glucose, maltose and isomaltose by α-amylase
isomaltase
maltase
sucrase
lactase
maltase
isomaltase
Digestion, Absorption and Transport
Absorption:
__________ (only): absorbed in jejunum & ilium. Then transported to liver and other tissues. Absorbed Actively, Passively, or Both (depending on which ________)
Monosaccharides
monosaccharide
Digestion, Absorption and Transport
In the intestine, there are 2 modes of absorption:
- ______= Na-dependent glucose transporter (SGLT-1)
- -Absorbs glucose + galactose
- -Symport: Co-transports Na+ into mucosal cells
- -Coupled to Na-K pump (‘antiport’) which moves Na+ out - ______= monosaccharide transporter (GLUT5)
Pentose and hexoses absorbed across concentration gradient
Active
Passive
Digestion, Absorption and Transport
_________: Passive-facilitative = Brain, kidney, placenta, colon, RBCs
GLUT-1
Digestion, Absorption and Transport
_______: Passive-facilitative–For rapid uptake = Liver, pancreatic β cells, kidney Intestine
—->blood….___-______ syndrome
GLUT-2
Fanconi-Bickel
Digestion, Absorption and Transport
_____: Passive-facilitative = Brain(neurons), kidney, placenta
GLUT-3
Digestion, Absorption and Transport
_______: ACTIVE –ENERGY IS USED! =Heart, skeletal ms., adipose, Insulin-stimulated transporter for ACTIVE uptake of ______
GLUT-4
glucose
Digestion, Absorption and Transport
GLUT-5: Passive-facilitative “___ _____” = Small Intestine For uptake of pentoses For hexoses when [high]
Fructose transporter
Digestion, Absorption and Transport
Transport:
1–Brain: Depends on ____ & ______ for
glucose (primary energy source)
2—May SLOWLY adapt to use fatty acids/ketone bodies
3–Abrupt _______ may cause coma or death
GLUT-1 and GLUT-3
hypoglycemia
Glucose Absorption
What affects the rate of absorption?
- Resistance of _____ to enzyme digestion
- Activity of _____ ______ at brush border
- Presence of other dietary factors (all SLOW rate)
a. FAT slows stomach emptying
b. NON-absorbable polysaccharides
c. viscous dietary fibers (pectins, β-glucans)
dilute enzyme concentration
starch\
digestive enzymes
***Therefore, a diet rich in whole foods, such as fruits, vegetables, legumes, nuts and minimally processed grain SLOWS the pace of glucose absorption.
Glucose Absorption
Glucose is absorbed (______) across the intestinal cell TO portal blood TO liver
1–The liver removes about ___% of the absorbed glucose for oxidation and storage as glycogen
2–Glucose exits liver, enters systemic circulation. Then, glucose is available for insulin-dependent uptake by ______ tissues
GLUT -2
50%
peripheral
Glycemic Index:
Measurement of blood glucose following the
consumption of a carbohydrate food. Compared to the consumption of equal amount of carbohydrate in D-glucose (old days – white bread)
Glycemic Index of Glucose: 100
GI measures _____ of carbohydrate food
quality
Factors Affecting Glycemic Index
- Cooking Methods:– The more cooking/processing, the ______ the Glycemic Index
- Physical Form of food:– The more _______ the food (whole grain), the SLOWER it is digested and the LOWER the GI
• Type of Starch
Amylopectin > Amylose (potatoes, corn) (legumes: kidney beans, lentils)
• Fiber:
– SOLUBLE fibers SLOW digestion, lowering a food’s GI
– (Oatmeal, dried beans, some fruits and vegetables)
• Sugar:
– Fructose, in fruits, is metabolized SLOWLY, lowering GI
higher
fibrous
Glycemic Load
• (Glycemic Index)(grams of avail. carbs in food)/ 100
• Measures the quantity and quality of a
carbohydrate’s effect on _____ ______ and insulin release
blood glucose
Glycemic Index
• High GI diet is a predictor of ______ __________,
hypertension, and diet-induced _______ of colon & breast
• Low GI diet is correlated with low cholesterol, low LDL, elevated HDL
So… combine low GI diet with low-fat diet for
weight management
Type II Diabetes
cancers
Hormones in Carb Metabolism
4 Major Modes of Hormone Action. Hormones bind to receptor and activate:
- Protein tyrosine kinase
- Adenylate cyclase —->cAMP
- Guanylate cyclase —–> cGMP
- Hormone Response Element (on gene)
KNOW
Hormones in Carb Metabolism X 4
- Protein tyrosine kinase
A. Hormone binds Receptor
B. Activates Protein Tyrosine Kinase
C. Phosphorylates proteins
Hormones utilizing this X 4 = ??
Insulin
IGF-I,
IGF-II
Growth Hormone
Hormones in Carb Metabolism X 4
- Adenylate cyclase
A component of GTP-dependent ‘G protein complex’
ATP—>cAMP—> activates cAMP-dependent protein kinase—>phosphorylates proteins/enzymes
Hormones utilizing this system X 4 =??
Epinephrine,
glucagon,
calcitonin,
ADH
Hormones in Carb Metabolism X 4
- Guanylate cyclase
A component of GTP-dependent ‘G protein complex’
GTP—->cGMP—->activates cGMP-dependent
protein kinase—–>phosphorylates proteins/enzymes
***Hydrolyzed by cGMP phosphodiesterase
(Viagra inhibits cGMP phosphodiesterase)
Hormones utilizing this system: X 2 =??
1—Nitric oxide (NO)
2—Arginine——-> Citrulline + NO
(Nitric Oxide = Synthase)
Hormones in Carb Metabolism X 4
- Hormone Response Element (HRE)
– Hormones can bind receptors or diffuse across
cell membrane and nuclear membrane
– Bind to segment of DNA “HRE”
– Regulates transcription (up or down)
Hormones utilizing this system: X 9!!
Androgens, estrogens, Thyroxins (T3, T4), calcitriol, glucocorticoids, mineralocorticoids, progestins, Retinoic acid (vitamer of vitamin A), Vitamin D
Blood glucose
• Blood glucose
– Normoglycemic: = 60-100 mg/dL
– Hyperglycemic: = ____________
– Hypoglycemic: = ___________
• Factors affecting blood glucose:
– Diet, hormones, metabolites, PAL, BMI, WHR
• After eating (postprandial), blood glucose can be 117-
130 mg/dL
– Will return to fasting level ~1.5 hr
• HbA1c normal levels 4.6-5.4% (5.1%~ 100mg/dL)
> 100 mg/dL
Blood glucose
Diabetes mellitus: one or more of the following:
1. Fasting blood glucose > 126 mg/dL
2. Random blood glucose > 140 mg/dL
3. > 200 mg/dL 2hr after ingestion of 75g glucose
4. HbA1c (glycated hemoglobin) > 8%
• ___________ LOWERS blood glucose by
– Stimulating uptake in muscle and adipose
Insulin
Hormones in Carb Metabolism: INSULIN
Insulin _________ Glucagon/Epinephrine
– Increases entry of glucose and neutral amino acids into
target cells
– Increases protein synthesis in skeletal muscle
– Increases glycolysis (activates glucokinase, PFK-1)
– DECREASES gluconeogenesis (inactivates PEPCK gene)
– Increases glycogenesis (activates glycogen synthase)
– DECREASSES glycogenolysis (inactivates glycogen
phosphorylase)
– Increases lipogenesis (activates acetyl-CoA carboxylase)
– DECREASES lipolysis (inactivates hormone-sensitive lipase)
opposes
Hormones in Carb Metabolism:
Glucagon/Epinephrine OPPOSE Insulin – Increases protein BREAKDOWN in skeletal muscle – DEcreases glycolysis – INcreases gluconeogenesis – DEcreases glycogenesis – INcreases glycogenolysis – DEcreases lipogenesis – INcreases lipolysis
OPPOSITE OF INSULIN
Storage of Carbohydrates
• 2 forms:
____________–Stored in extra-cellular fluids
______________—Stored in liver and muscle
• Glycogen: polymer of glucose in α1—>4 and α1—>6
• Body content of glycogen fluctuates with diet and
physical activity
• Typical example: A 70 kg man may have an 18hr supply:
1—150-600 g in muscle
2–90-160 g in liver
3—5-25 g in blood (as glucose)
Glucose
Glycogen
Function of Carbohydrates
- Provide energy
- Biosynthesis of Lipids
- Biosynthesis of certain amino acids
- Biosynthesis of nucleic acids
- Biosynthesis of glycosaminoglycans (GAGs)
- FORMATION of _____+____________
glycoproteins and glycolipids
Function of Carbohydrates 1 OF 6
- Provide energy:
Metabolism of 1g carb = 4 kcal
Can be metabolized under aerobic OR anaerobic conditions
A. Protein and lipid MUST be metabolized under ___________ conditions
B. __________ regulated at 2 points:
– Glycogenolysis
– Glycolysis
AEROBIC
Metabolism
Function of Carbohydrates 2 OF 6
2. Biosynthesis of Lipids Dietary glucose: ~50% for energy release ~40% for fat synthesis ~10% for glycogen
Carbs provide:
For carbon backbone = _______________
For hydrogen / cofactor = ________
For bond energy = ___________
Acetyl-CoA
a. Carbs provide acetyl-CoA
b. Blood insulin increases = stimulates lipogenesis
NADPH
ATP
Function of Carbohydrates 3 OF 6
- Amino acid biosynthesis: by ____________
Transamination of pyruvate results in: _________, lactate, acetyl-CoA, citrate
transamination
alanine
Function of Carbohydrates 4 OF 6
Nucleic acid biosynthesis: PPP
R-5-P, ATP and GTP are all produced in carb metabolism,
and involved in synthesis of ___________
nucleotides
Function of Carbohydrates 5 OF 6
- Biosynthesis of Glycosaminoglycans – “GAGs”
(mucopolysaccharides) : polymers of carbohydrate derivatives, (esp. amino sugars and uronic acids)
Example 1: ______ _____: Joint lubricant in synovial fluid;
component of vitreous humor of eyes
Example 2: _____ ________: component of bone, cartilage and other CT
Example 3:_____ ________: Endogenous anticoagulant, and binds proteins to alter their function
hyaluronic acid
chondroitin sulfate
heparan sulfate
Function of Carbohydrates 6 OF 6
Biosynthesis of glycoprotein: Glycoproteins (mucoproteins): proteins with attached oligosaccharides
Key examples of glycoproteins:
- antibodies
- _____ _______ (req’d for VitB12 absorption)
- __________ : erythrocyte membrane protein
- When GAGs are ATTACHED TO PROTEIN, they are known as ________________ (or peptidoglycan)
Intrinsic factor
glycophorin
Proteoglycans
Daily Requirement, Deficiency & Excess
Deficiency could result in:
1– Ketosis
2– An excessive loss of ____ ________
3– Problems associated with lacking _____ _______
Carbohydrate deficiencies
• South Beach diet
• Ketogenic diet
• Alcoholism
Excess
– FNB: ___% kcal from sugar UL.
body protein
dietary fiber
20%
Lactose intolerance
Digestive problem in people who lack the intestinal enzyme ___________
• Undigested lactose:
– Absorbs an excess amt of ______
– Promotes the growth and fermentation of ________ =
excess gas & irritating substances = diarrhea, cramping, stomach pain.
lactase
water
bacteria
Lactose intolerance
• 2 types of lactase deficiency:
A–– ___________ of the lactase gene (post-infant)
• In people with ancestry from places other than northern Europe, central Africa, Indian subcontinent
B–– People who stop eating foods with lactose
• Lactase can be restored by gradually resuming lactose
consumption
Deactivation
Lactose intolerance
• Lactase (available w/o prescription) can be added to milk several hours in advance to _________ lactose.
A–– Addition of Lactobacillus acidophilus is ________ in preventing lactose intolerance
B–– ~___% of lactose intolerant people can eat yogurt because Lactobacillus bulgaricus and Lactobacillus thermophilus, which release β-galactosidase, are used in the preparation
pre-digest
ineffective
80
**From 1962 to 2000, worldwide intake of sugar
increased by 32% (74 kcal per capita per day)
Sugars: Are they really bad?
4 reasons why excess sugars are unhealthy:
1. Energy-dense = Get extra kcal easily= overweight, OB
- Poor in nutrients = May actually cause deficiency of
___________. Metabolism can deplete body’s reserve of __ vitamins, because need NAD, FAD coenzymes - Promote growth of bacteria= Oral bacteria in particular
= dental cavities and __________ disease - Lipogenic = Sugars cause release of insulin, activates glycolysis and acetyl Co-A carboxylase to make malonyl-CoA, ________ hormone-sensitive lipase which is lipogenic. (Anti-lipolytic)
micronutrients
B
periodontal
inactivates
Carbohydrate regulation of blood lipids
- Brain uses most of ____ g of glucose required daily
- If blood glucose <40 mg/dL = ___________
200
glycogenolysis
Carbohydrate regulation of blood lipids
If blood glucose >180 mg/dL = _________in urine
• High carb intake = ______ insulin levels
glucose
high
Carbohydrate regulation of blood lipids
• ~2hrs after meal, intestinal absorption is complete,
but insulin effects persist = ______ _______ DECREASES = body fears hypoglycemia = lipolysis = FA packed into VLDLs in the liver = __________
serum triglycerides
blood glucose
elevated
_____________– is a condition in which the body is unable to use (metabolize) the simple sugar galactose.
1— Hereditary metabolic defect (1:65,000)
(autosomal recessive)
2—_________ can be used to detect before birth
Symptoms: Anorexia / Weight loss Vomiting / Diarrhea Lethargy Icturis / Hepatomegaly Poor growth Cataracts MR Edema Death
Galactosemia
Amniocentesis
Galactosemia
Treatment – Avoid foods with galactose! – These foods include • Milk, milk products • Legumes • Organ meats • Cocoa • Chocolate • Coconut • Some people may develop an alternative enzyme to metabolize \_\_\_\_\_\_\_\_\_\_\_\_, usually after 6 years of age
D-galactose
Diabetes Mellitus
• Type I: Insulin-dependent–Body does NOT produce insulin
• Type II: Non-insulin-dependent–Faulty _____ _______
• Gestational—–Hormones affect level of glucose __________
Symptoms: 1---General weakness 2---Polydipsia 3---Polyuria 4---Polyphagia 5--Ketosis (fruit breath and ketonuria) 6--Hyperglycemia 7--Glycosuria 8---Coma (severe case)
insulin receptors
transporters
Diabetes Insipidis
Similar symptoms as DM, but different CAUSE:
Disorder of the ______ ________ or hypothalamus =
deficiency of vasopressin (ADH) = REDUCED water
resorption. Trauma or _______ may also cause this
condition.
Treatment: vasopressin and __________
pituitary gland
tumors
diuretics
Risk factors for DM type II
Overweight: BMI> ___ kg/m2
1– Overnight fasting blood glucose levels significantly correlate to BMI and WHR
2– (correlation to total body fat level is weaker)
3—_____ _______ = Ethnic group: high risk groups include– African-, Native-, Asian-American, Hispanic / Latino, Pacific Islander
25
Family history
Risk factors for DM type II
Gestational diabetes: during pregnancy or having
a baby > __ lbs
• Hypertension: (consistently > 140/90 mm Hg)
• Fat & Cholesterol: HDL _______ mg/dL
9
250
Blood glucose: Lab criteria
Normal blood sugar: _____-______ mg/dL
60-100
Blood glucose: Lab criteria
Diabetes mellitus: one or more of the following:
– Fasting blood glucose > ____ mg/dL
– Random blood glucose >_____ mg/dL
– > 200 mg/dL 2hr after ingestion of 75g glucose
– HbA1c (glycated hemoglobin) > 8%
***Normal blood sugar: 60-100 mg/dL
126
140
Blood glucose: Lab criteria
________ ________ INCREASES the risk of Type I diabetes. 3+ of the following:
– _________ obesity
– Impaired Fasting Glucose (IFG) > _____ mg/dL
– Dyslipidemia (Fasting TG > 150 mg/dL)
– Low HDL-C (
Metabolic Syndrome
Central
110
Hypoglycemia
• Low blood glucose = Sugar or fruit juices used to relieve emergency condition • Characterized by – Nervousness – Tension – Sweating – Nausea – Headache – Convulsion – Coma – Death ***Symptoms related to: Excessive \_\_\_\_\_\_\_\_\_ release. Low brain glucose level = \_\_\_\_\_\_\_
epinephrine
Ketosis
Prebiotics & Probiotics
Functional Food = Any food or food ingredient that may provide a health benefit BEYOND traditional nutritional function.
– Examples: inulin, oligofructose (__________)
– Lactobacilli, bifidobacteria, others including both
lactic acid and maybe some non-lactic acid bacteria
(___________)
prebiotics
probiotics
Prebiotics
Enhances the colonization of HEALTH promoting bacteria in the ______ intestine.
1–– _____-______ food ingredient that beneficially affects the host’s health by selectively stimulating
growth and/or activity of one or a number of bacteria in the colon.
2–– Does NOT depend on administration of a viable
microbe.
3–– Inulin, oligofructose preferentially PROMOTE growth
of bifidobacteria
large
Non-digestable
Prebiotics
• Inulin and Oligofructose: polymers of fructose (_______) connected by α2—>1 linkages.
–______= 2-60 fructose monomers
– Oligofructose
fructan
Inulin
sucrose
Prebiotics
1 • Inulin and Oligofructose: 2 • Average American diet: – 2.6 grams inulin & 2.5 g oligofructose 3 • MAJOR food sources of FRUCTAN: – \_\_\_\_\_\_ (70% total dietary fructan) – Onions (25%) – Bananas and garlic (remainder) 4 • Fructans have NO toxicity, except high intake may cause \_\_\_\_\_\_\_\_\_\_
Wheat
flatulence
Prebiotics: As additives
1• Both inulin and oligofructose have been used as
FIBER in food products
2• _________ is most SOLUBLE. Its sweetness is about 30-50% of sucrose… used as sugar substitute in dairy products, baking goods and granola bars
3•___________ is less soluble. It has a smooth creamy texture when sheared in water or milk… has a fat-like taste. Used as fat substitute
oligofructose
Inulin
Prebiotics: Effects on the body
• Limited energy source
1–– Fructans like other soluble fibers, are non-digestible
in _________ intestine.
2–– They are ____________ by bacteria in LARGE INTESTINE = short-chain fatty acids, lactic acid, pyruvic acid, ethanol, and others = these CAN be absorbed and
metabolized for energy release.
3–– Caloric value of fructans ranges from 0-2.5 kcal /
gram —->______ kcal / gram average
small
fermentable
1.5
Prebiotics: Effects on the body
- Effects at intestine
- Increase fecal bulk (_________ diarrhea)
- Prevent bile re-absorption (__________ constipation)
- Increase intestinal flora
- increase short fatty acids
- Increase vitamin B7 and K synthesis
- Increase mineral absorption
decrease
decrease
Probiotics
Definition: “A preparation of, or a product containing, viable defined microorganisms in sufficient numbers which, by implantation or colonization, alter the ________ in a compartment of the host and thereby exert health effects in this host”
Unlike commonly thought, NOT limited to the intestine…
could be other parts of gut, vagina, or skin.
microflora
Probiotic microbes
• Microbes – Lactobacillus –12 species – Bifidobacterium – 7 species – Streptococcus thermophilus – Lactic-acid bacteria – 6 other species – Non-lactic acid bacteria – maybe ? – Yeast – Sacchromyces –proposed • Available as fermented probiotic products – Dairy-based yogurt, cheese, acidophilus milk – Non-dairy: brined olives, sauerkraut, Togwa (cereal/ flour with bacteria) – Commercial lyophilized bacteria OTC
KNOW
Probiotics: Criteria
- Human origin
- Non-pathogenic
- Resistance to technological processing and delivery
- Resistance to gastric _______
- Resistance to bile __________
- Viability in GI environment
- Adherence to epithelial tissue
- Production of antimicrobial substances
- Ability to modulate host’s immune response
- Ability to modulate host’s biochemistry
A. Absorption of cholesterol and minerals, lactase activity and vitamin production
acidity
toxicity
Probiotics: Known Effects
1--Balance of intestinal \_\_\_\_\_\_ 2--Reduction of \_\_\_\_\_\_\_\_\_\_\_\_ symptoms 3--Relief from constipation 4--Relief of irritable bowel syndrome 5--Beneficial effects on mineral metabolism, esp. bone density and stability
flora
allergic
Probiotics: Known Effects
6–Protection against malignancy
7–Reduction in serum cholesterol and TGs
8–Enhanced________ function
A. Increased phagocytic activity and ___ cell activity
B. Increased INF-α
9. Protection against rotavirus diarrhea
10. Protection against ‘traveler’s diarrhea’ (_______)
immune
NK
E. coli
Focal Points
1 • The major nutrients with roles in the human body include energy-containing macronutrients (carbohydrates, lipids, protein, and alcohol) as well as the micronutrients (vitamins and minerals.)
2 • The indigestible food component, fiber, is essential for health, especially related to the GI tract and cardiovascular system, but ____% of Americans do NOT get enough fiber.
3 • Changing concepts regarding the structure, function, and utilization of nutrients in the body are important to keep in mind because they determine the impact of _____ _________ or excesses on health and disease management.
80%
nutrient deficiencies
