Exam 4 - Nutrition Flashcards
1
Q
essential organic compounds needed in small amount
A
- not synthesized by body
- measurable decline in health if missing from diet
2
Q
13 total vitamins
A
- Fat soluble: A, D, E, K
- Water soluble: B and C
3
Q
Vitamins needed for
A
- energy metabolism
- growth
- development
- maintenance
4
Q
Fat-soluble vitamins are absorbed with:
A
- dietary fats
- adequate absorption depends on bile and pancreatic lipase
- 40-90% absorbed under optimal conditions
- diseases and drugs such as orlistat can impair absorption
5
Q
water soluble vitamins absorption
A
not dependent on dietary fats: 90-100% absorption rate
6
Q
all vitamins
A
- digestive process in the stomach begin the release of vitamins from food
- digestive enzymes produced by the pancreas aid in the release of vitamins from food
7
Q
Fat-soluble vitamins only
A
- bile produced in the liver and stored in the gallbladder aids in fat-soluble vitamin absorption
- fat-soluble vitamins are absorbed in the small intestine, along with dietary fat, and carried by chylomicrons into the lymphatic system
- absorbed in the small intestine and released directly into the blood
8
Q
vitamin K only
A
small amounts of vitamin K are made by bacteria in the ileum of the small intestine and in the large intestine
9
Q
Storage of fat-soluble vitamins
A
- stored in the liver and adipose tissue
- less storage of vitamin K
10
Q
Storage of water-soluble vitamins
A
- some storage of B-6 and B-12
- other excreted rapidly
11
Q
Storage of vitamins in the body
A
- best to meet DRIs daily, but for most vitamins it takes weeks of low intake before symptoms of deficiency develop
- toxicity possible if too much is consumed
12
Q
Vitamin A - retinoids
A
- preformed vitamin - biologically active
- mostly animal source
13
Q
Vitamin A - carotenoids
A
- provitamin A
- need to be activate in body
- mostly plant source
14
Q
Vitamin A in foods
A
- retinoids are found in liver, fish, fish oils, fortified milk, and eggs
- Carotenoids are found in dark-green and yellow-orange vegetables and fruits: beta-carotene has greatest amount of provitamin A activity
- 70% of vitamin A in North American diets comes from animal sources
15
Q
Absorption, transport, storage, and excretion of Vitamin A
A
- 90% of vitamin A is found in liver, which stores enough retinyl ester to last several months
- it is released into bloodstream from the liver as a retinoid bound to retinol-binding protein (RBP) and transthyretin
16
Q
Functions of vitamin A retinoid
A
- growth
- development
- cell differentiation
- vision
- immune function
17
Q
Vision
A
- retinal is needed in the retina, as it turns visual light into nerve signals to the brain
- rods and cones are sensory elements on retina: rods are responsible for translating objects into black-and-white images and detecting motion; cones are responsible for translating objects into color images
18
Q
Vitamin D
A
- conditional vitamin
- prohormone
- vitamin: precursor from sunlight or diet
- hormone: activated 1, 25-(OH)2D2 is produced in the body
- in the gut, activated D switches on genes for proteins that enable calcium absorption
19
Q
Vitamin A Deficiency Disease
A
- least common vitamin deficiency along with vitamin E
- major public health problem in developing countries (leading cause of non-accidental blindess)
20
Q
Vitamin D3
A
- produced naturally in skin
- form of most supplements
- FYI vitamin D2: derived from ergosterol; plant origin
21
Q
25-hydroxyvitamin D3
A
- calcifediol
- 25-OH added in liver
22
Q
1, 25-dihydroxyvitamin D3
A
- calcitriol
- fully activated form
- 1-OH added in kidney under control of PTH
- sometimes abbreviated 1, 25-(OH)2D
23
Q
A
24
Q
Functions of Vitamin D
A
- calcium absorption and maintenance of levels
- vitamin D may also help regulate immune function, the function of other hormones, cell cycle, cardiovascular and nervous system function
- this does not mean that supplementation will help any health conditions related to these symptoms
25
Vitamin D needs
- RDA for most adults is 15 micrograms/600 IU
- for age 70+ 20 microgram/800 IU
- breastfed babies should be given vitamin D supplement
26
Vitamin D deficiency diseases: Rickets
- rickets: abnormal mineralization of bones in children
- signs include enlarged head, joints, and rib cage, deformed pelvis, bowed legs
- cab be associated with fat malabsorption, cystic fibrosis, dark skin, low milk intake, minimal sun exposure
27
Vitamin D deficiency diseases: Osteomalacia
- poor calcification of newly synthesized bone in adults
- leads to fractures
- can be seen in adults with: impaired fat absorption, dark skin, limited UV exposure
28
Vitamin D toxicity
- generally, only seen with excess supplementation
- upper level is set at 100mg/4000 IU day for 9 and older
- above this can cause: excess blood calcium, bone loss, calcification in kidneys, heart, and lungs
29
Should I take vitamin D and/or have my level checked?
Routine vitamin D supplementation does not prolong life, decrease the
incidence of cancer or cardiovascular disease, or decrease fracture rates.
Screening asymptomatic individuals for vitamin D deficiency and treating
those considered to be deficient do not reduce the risk of cancer, type 2
diabetes mellitus, or death in community-dwelling adults, or fractures in
persons not at high risk of fractures. Randomized controlled trials of vitamin
D supplementation in the treatment of depression, fatigue, osteoarthritis,
and chronic pain show no benefit, even in persons with low levels at
baseline.” (Am Fam Physician. 2018;97(4):254-260.)
30
Vitamin E
- family of 8 naturally occurring compounds:
- tocopherols: alpha, beta, gamma, delta
- tocotrienols: alpha, beta, gamma, delta
31
Vitamin E: alpha-tocopherol
- main functions: boosts antioxidant defense, protects cell membranes, enhances immune function
- daily recommendation: 15 mg
- good sources: vegetable oil, nuts, avocado
32
Vitamin E needs
- RDA is set at 15 mg/day alpha-tocopherol: based off prevention of hemolysis during in vitro studies, not based on long term health and disease risk, RDA is based on prevention of deficiency - might be too low
- average adult consumes 7-8 mg/day (marginal deficiency, symptoms rare)
- daily value is 30 IU: this system accounts for activity of different forms
33
Absorption, transport, storage, and excretion of Vitamin E
- absorption by passive diffusion
- variable: 20-70%
- travels to liver in chylomicrons
- liver repackages vitamin E into other lipoproteins for delivery
- does no accumulate in the liver; 90% is localized to adipose tissue
34
Functions of vitamin E
- antioxidants, especially in lipid-rich areas
- research on supplementation has been mixed: overall, supplementation of E beyond the RDA is not recommended, may be harmful in certain situations: increased cancer and bleeding risk
35
Vitamin E deficiency
- rare but possible in: those with fat malabsorption conditions, smokers, preterm infants
- characterized by: premature breakdown of red blood cells, which leads to development of hemolytic anemia, impaired immune function, neurological changes in spinal cord and peripheral nervous system
36
Vitamin K
- assists in blood clotting
- promotes bone calcification
- prevents blood vessel calcification
- Phylloquinones (vitamin K1): from plants, the main biologically active form
- menaquinones (vitamin K2): fermented foods, bacteria in large intestine
37
Vitamin K sources
- 10% absorbed daily comes from bacterial synthesis in colon
- remainder comes from food
- heat stable
- most people meet AI
38
Absorption, transport, storage, and excretion of vitamin K
- 80% if dietary vitamin K is absorbed and incorporated into chylomicrons
- menaquinones synthesized by bacteria are absorbed by passive diffusion in the large intestine
- incorporated into lipoproteins for transportation
39
Functions of Vitamin K
- used for posttranslational modification of proteins: coenzyme for synthesis of Gla domains
- Key proteins with Gla" prothrombin and other coagulation factors, osteocalcin
40
Warfarin
- patients should maintain steady intake of Vitamin K
- Vitamin K can be used to reduce warfarin effects
41
Vitamin K Deficiency
- can occur in newborns: stores are low and bacteria not yet present in colon, standard practice to give vitamin K injection at birth
- otherwise rare, but can occur in: prolonged antibiotic used, impaired fat absorption
- mega-dosesof vitamin A and E negatively affect either absorption or action of vitamin K
42
Water soluble vitamin overview
- only small amounts are stored in the body: risk of toxicity is low for most, readily removed by the kidneys and excreted in urine
- most easily destroyed by cooking compared to fat-soluble vitamins: can leech into cooking water, retention is greatest when steaming, stir-frying, and microwaving, thereby limiting exposure to heat and water
43
B-vitamins function as coenzymes
- small, organic molecules that combine with inactive enzymes to form active enzymes
- in foods, B-vitamins are present as individual molecules, in coenzyme form, or complexed with proteins
- digestion frees vitamin molecules from complexes
- most B-vitamins are contained in the germ and bran of wheat
- in the US white flour is enriched with 4 B-vitamins and iron: thiamin, riboflavin, niacin, folic acid
44
Thiamin (vitamin B-1)
- found in small amounts in a wide variety of foods
- some foods contain antinutrients that lower the bioavailability of thiamin
- antinutrients are controversial: not linked to deficiency, and may have beneficial effects
45
Thiamin Needs and Upper level
- most people get enough between natural sources and fortified foods
- no upper level has been set
46
Functions of Thiamin
- thiamin pyrophosphate (TPP) is a cofactor in certain decarboxylation reactions
- pentose phosphate pathway: coenzyme for transketolase
- needed for normal function of nervous system
47
Thiamin deficiency Beriberi
historically seen in populations where diet consisted primarily of white rice
48
Dry beriberi
- peripheral neuropathy and weakness
- muscle pain and tenderness
- Wernicke-Korsakoff syndrome is a form of dry beriberi associated with alcoholism (psychosis and memory impairment
49
Wet beriberI
- affects cardiovascular system
- congestive heart failure
- edema
50
Riboflavin (vitamin B-2)
- small amount from a variety of foods, including enriched flour
- most people get enough
- no upper level
- excess goes into urine; causes bright yellow color that glows under black light
51
Functions of Riboflavin
- component of 2 coenzymes of energy metabolism: Flavin mononucleotide (FMN) and Flavin adenine dinucleotide (FAD)
- formation of other B-vitamins: Niacin from tryptophan and active form of vitamin B-6
- antioxidant function: required for synthesis of glutathione
52
Riboflavin Deficiency
- ariboflavinosis primarily affects the mouth, skin, and red blood cells
- symptoms include: inflammation of throat, stomatitis, glossitis, angular cheilitis, seborrheic dermatitis
- often occurs with deficiency of other B-vitamins
53
Niacin (Vitamin B-3)
- exists in 2 forms: Nicotinic acid and Nicotinamide
- both forms are used to synthesize niacin coenzymes: Nicotinamide adenine dinucleotide (NAD+) and Nicotinamide adenine dinucleotide phosphate (NADP+)
54
Niacin in foods
- preformed in poultry, meat, fish, enriched bread, mushrooms, and peanuts
- can be synthesized from tryptophan: Trp makes up about 1% of protein, divide grams protein by 6 to get approximate niacin equivalent
55
Niacin Needs and upper level
- average intake is greater than the RDA
- upper level about 2x the RDA however, only applies to supplements and fortified foods
56
Absorption, transport, storage, and excretion of Niacin
- free Niacin is readily absorbed from stomach and small intestine by active transport and passive diffusion
- bioavailability is low in some grans, especially corn (bound to protein)
- Niacin can be released by soaking in calcium hydroxide (lime water)
57
Functions of Niacin
- coenzymes participate in oxidation-reduction reactions
- required for metabolism of all energy-yielding nutrients
- at least 200 different reactions
58
Niacin Deficiency
- the only nutritional deficiency to read epidemic proportions in the US
- pellagra: symptoms include dermatitis, rough red rash around body, diarrhea, dementia
- death can occur if untreated
59
Pantothenic Acid (vitamin B-5)
- part of coenzyme A: used throughout the body energy metabolism
- found in many foods; higher levels in unprocessed
- isolated deficiency rare to non-existent
- no observed toxicity
60
Biotin (vitamin B-7)
- coenzyme for several carboxylase enzymes
- specific example: carboxylation of pyruvate to form oxaloacetate
- small amounts in a wide variety of foods
61
biotin deficiency
- deficiency extremely rare
- biotinidase deficiency: genetic mutation with non-functional enzyme and cannot release biotin from food
- raw egg diet: avidin
62
Vitamin B-6
- family of 3 compounds: pyridoxal, pyridoxine, pyridoxamine
- primary vitamin B-6 coenzyme is pyridoxal phosphate (PLP)
63
Vitamin B-6 in foods
- sources: meat, fish, poultry, whole grains, some fruits/veg
- most people are close to the RDA
- UL is about 50x the RDA: tingling, numbness, higher doses: permanent nerve damage
64
Functions of Vitamin B-6
- coenzyme for 100+ reactions
- specific examples: amino acid synthesis, glycogen breakdown, hemoglobin synthesis
65
Vitamin B-6 Deficiency
- severe deficiency is rare
- certain medications can cause low blood levels of B-6: Levodopa and Isoniazid
- deficiency causes microcytic hypochromic anemia
66
Folate (vitamin B-9)
- folate is a generic term for several naturally occurring derivatives
- folic acid is a specific form in supplements and fortified foods
67
Folate in food
- major sources: leafy green vegetables and fortified foods
- mandatory enrichment of grains began in 1998
- food processing and preparation destroys 50-90%
68
Folate needs
- most people meet RDA
- however, about 20% of women of childbearing age do not get enough
- upper level is 2-3x RDA; greater intake masks B-12 deficiency
69
Functions of folate
- coenzyme form is tetrahydrofolic acid
- functions in reactions where a single carbon is transferred
- most significant function is in nucleotide synthesis
70
Neural tube defects
- linked to deficiency of folate and enzyme mutations in the folate pathway
- spina bifida: paralysis, hydrocephalus, learning disabilities
- anencephaly: lack of brain formation, fatal shortly after birth
71
Vitamin B-12
- cobalamin (most supplements contain cyanocobalamin)
- only vitamin that contains cobalt, and most chemically complex overall
- comes from only animal sources
- stored in large quantities
- complicated absorption
- cyanocobalamin form of vitamin B-12 forms 2 active coenzymes: Methylcobalamin and 5-deoxyadenosylcobalamin
72
Vitamin B-12 needs and upper level
- most North Americans eat plenty of animal products and exceed RDA
- vegans need to supplement
- body can store 2-3 year supply
- no upper level is set
73
functions of vitamin B-12
- synthesis of methionine from homocysteine (also regenerates active folate)
- metabolism of odd-numbered fatty acids
74
Vitamin B-12 deficiency
- inflammation/autoimmune conditions in stomach: Pernicious anemia: anti-intrinsic factor antibodies. H. pylori infection
- problems with absorption: Crohn's
- symptoms: macrocytic anemia, neurological changes and nerve degeneration, elevated plasma homocysteine concentrations, which may increase risk for heart attack and stroke
75
Vitamin C
- ascorbic acid
- donates electrons in oxidation-reduction reactions
76
Vitamin C in foods
- richest sources are: citrus fruits, peppers, green vegetables
- 5 servings/day of fruits and vegetables provide enough vitamin C
- least stable vitamin and easily lost in storage, processing, and cooking
77
Vitamin C needs
- most people get enough but deficiency does exist
- about 6% have blood levels indicating deficiency
- smokers need about 33% more vitamin C
- 200-400 mg/day maximizes plasma level: with greater intake, absorption decreases and excretion increases
78
Upper level and tissue storage
- upper level is 2000 mg/day (compare to RDA of 90 mg)
- based on adverse gastrointestinal effects: bloating, stomach inflammation, diarrhea
- high concentrations are stored in: pituitary and adrenal glands, white blood cells, eyes, brain
79
Functions of vitamin C
- antioxidant defense functions
- regenerates oxidized vitamin E
- may have a role in aqueous environment similar to vitamin E's role in lipid rich areas
- cofactor for several metalloenzymes
- examples of substances synthesized by vitamin C dependent metalloenzymes: collagen, tyrosine, thyroid hormone, neurotransmitters
- iron absorption: facilitates absorption of non-heme iron
- immune functions: white blood cells contain high levels of both reactive oxygen species and vitamin C
- may protect against self-inflicted damage
80
Vitamin C deficiency
- early symptoms appear after 20-40 days on a vitamin C free diet
- many symptoms are related to weak collagen: petechiae (pinpoint hemorrhages), bleeding gums, impaired wound healing, bone pain, fractures
- psychological symptoms
81
Vitamin C, Cancer, and Heart Disease
- no conclusive evidence regarding cancer and heart disease prevention
- increasing vitamin C intake has small benefit in some studies, no effect in others
- some studies have shown benefits of vitamin C from dietary sources but not from supplements
82
Vitamin C and colds
- many trials conducted with supplements ranging from 250-2000 mg/day
83
Will supplementation prevent you from getting a cold?
- general population: NO
- people under intense physical stress (marathon runners and soldiers): Yes, 50% reduction in incidence
84
Will suplementation reduce the duration of a cold
- if started before getting sick, duration is about 1 day shorter
- if started after getting sick, no effect
85
water
- maintaining the right amount of water in the body is essential to life
- adults can survive several weeks without food, but only days without water
- there are no reserves for water in the body, like for the other macronutrients
86
Functions of water
- solvent for all body fluids such as blood saliva, amniotic fluid
- transports nutrients, oxygen, wastes
- participates in hydrolysis reactions
- temperature regulation
87
water needs
- needs vary with body size, physical activity, environmental conditions and dietary intake
- adequte intake: 15 cups for men (120 oz), 11 cups for women (88 oz)
- the AI includes water intake from food and metabolism, so you don't need to drink this much
88
Water input
- fluids (8 cups)
- water contained in food (2 cups)
- water produced from metabolism (1.25 cups)
89
Insensible losses
- skin perspiration (3 cups)
- lung respiration (1.25 cups)
- feces (0.4 cups)
- sensible losses: urine (6.75 cups)
90
Notes about fluid intake
- don't need to worry too much about dehydration with caffeinated beverages
- alcoholic beverages increase urine output and may lead to dehydration
- in the U.S. bottled water is no safer than municipal tap water. Some bottled water is simply municipal tap water that has gone through additional purification
91
Dehydration
- can be caused by: medical conditions where water is lost: diarrhea, vomiting, fever, diabetes, burns
- heavy exercise
- hot weather, dry environments, high altitudes
92
Overview of minerals - essential, inorganic elements
needed in small amounts for function, growth, and maintenance of tissues
93
major minerals
need 100 mg or more daily, found in larger quantities in the body
94
trace minerals
needed/stored in smaller amounts
95
food sources of minerals
- found in both animal and plant food
- bioavailability issues: large doses of one mineral may interfere with absorption of another, chemicals in food many decrease absorption
- quantity of minerals is influenced by agricultural practices and food processing
96
Absorption and bioavailability continued
- regulated by physiological need
- physiological factors: reduction of iron by HCl or vitamin C, vitamin D increases absorption of calcium, magnesium and phosaphate
- plant compounds that bind minerals phytic acid, oxalic acid, polyphenols
97
Phytic acid
- wheat grain, legume fiber, and unleavened breads
98
Oxalic acid
leafy green plants
99
Polyphenols
tea, dark chocolate, and wine
100
transport and storage of minerals
- travel in blood in free form or bound to proteins
- storage varies: calcium and phosphorus are stored in bones and teeth, iron stored in small amounts in liver and bone marrow, trace mineral storage is very small
101
Sodium
- there are many sources of sodium, even if you never touch a salt shaker
- processed foods are largest source
- table salt, NaCl, used for flavor
- preservatives, leavening agents, anticaking agents are all sodium salts
102
Absorption, transport, storage, and excretion of sodium
- almost all sodium consumed is absorbed by active transport in small and large intestines. Energy for absorption is supplied by sodium-potassium pump
- in the body, most sodium is dissolved in extracellular fluid
- excretion: kidneys excrete excess, when Na+ levels and/or blood pressure are low, aldosterone causes sodium retention
103
Functions of sodium
- required for normal nerve and muscle function: establishes membrane potential, moves into excitable cells during action potential
- helps absorb glucose and some amino acids in small intestine
- aids in water balance and maintains blood pressure
104
Sodium deficiency
- extremely rare as a dietary deficiency (almost everyone consumes enough)
- sweat seems salty but is actually hypotonic compared to blood, in other words, you lose water faster than salt when you are sweating
- vomiting and diarrhea, especially in infants, can cause sodium depletion
- more common cause of hypoatremia is excess water consumption
105
Excess sodium and upper level
- excess sodium generally gets excreted by the kidneys without serious acute effects: risk factor for cardiovascular disease, certain individuals may be more salt sensitive
- greater than 2g/day leads to more calcium being excreted in urine, but so far has not been linked to osteoporosis
106
Potassium
- fruits, vegetables are best sources, but small amounts in many foods
- also supplied by salt substitutes (potassium chloride)
- potassium needs: adequate intake is 4700 mg/day
- daily value is 3500mg
- most people do not get enough
107
Potassium functions
- 95% is found inside cells-major intracellular cation
- works in many of the same areas as sodium: membrane potential, nerve and muscle function
- reduces calcium excretion
- may blunt the effects of high salt intake and help keep blood pressure normal: suppresses renin-angiotensin system and promotes secretion of sodium and water
108
Potassium deficiency
- low blood levels (hypokalemia) can be immediately life-threatening due to arrhythmia
- may occur with diuretic drugs or eating disorder
- dietary deficiency generally does not cause hypokalemia but can increase chronic disease risk: stroke, osteoporosis, kidney stones
109
Potassium excess
- hyperkalemia can also cause fatal arrhythmia
- not observed due to high dietary intake
- kidney disease, supplement overdoes, potassium sparing diuretics
110
Chloride
- almost all comes from table salt (NaCl)
- most is found in extracellular fluid
- helps maintain membrane potentials
- also component of HCl in stomach
111
Hypertension and Nutrition
- 1 in 3 adults has hypertension
- most cases are primary (essential) hypertension: develops over several years as a response to changes in the arteries, kidneys, and sodium/potassium balance
112
Calcium
- many adults do not meet RDA
- groups with higher requirements tend to have lowest intakes
- bioavailability varies widely - RDA assumes mixed diet and is a target for total calcium, not bioavailable calcium
- must consider source and overall amount
113
What has more calcium than milk
- Chinese cabbage, mustard greens, turnip greens, brussels sprouts, broccoli, kale, cabbage, cauliflower
114
Calcium supplements
- prefeered to obtain calcium from diet, better absorption, possible increased heart attack risk with supplements (artery calcification)
- supplements have not been demonstrated to protect against fractures
- US preventive services task force recommends against supplementation
115
Functions of calcium
- development and maintenance of bones and teeth
- blood clotting
- transmission of nerve impulses
- muscle contraction
- cell metabolism
- the body maintains blood calcium concentration within a narrow range
- when calcium in blood decreases, parathyroid hormone (PTH) is secreted
116
PTH increases: (calcium)
- absorption from gut
- reabsorption from kidney
- resorption from bone
117
Bone development and maintenance
- bone consists of protein, (mainly collagen) and minerals (especially calcium and phosphorus)
- minerals form hydroxyapatite, which binds to collagen
- enamel and dentin also contain hydroxyapatite
118
osteoporosis prevention
- diets including calcium, vitamin D, magnesium, phosphorus, potassium, vitamin K, and protein
- weight-bearing activity
- avoid smoking
119
phosphorus
- found in many foods and food additives
- deficiency extremely rare
- toxicity from nutrition extremely rare; hyperphosphatemia occurs due to kidney disease
- absorption enhanced by vitamin D
- most of body's supply is in bone (hydroxyapatite)
120
Phosphorus functions
- phosphates are the main intracellular
- components of: ATP, creatine phosphate, DNA and RNA, phospholipids, other enzymes and cellular messengers, regulation in ac0d-base balance
121
Magnesium
- leafy green vegetables are good sources since it is a component of chlorophyll
- unrefined grains, nuts also good
- average intakes are below RDA
- about half of body's supply is stored in bone
122
Magnesium functions
- stabilizes ATP
- contributes to bone structure and mineralization
- membrane potential
- adequate intake may reduce risk of metabolic syndrome, hypertension, cardiovascular disease
123
Sulfur
- a major mineral, provided by sulfur-containing amino acids like methionine and cysteine
-required for: stabilization of protein structure and detoxification (glutathione)
