Chapter 13 -- part 3
Vitamin B-12 factors that decrease absorption -Atrophic ______ Decreases HCl and digestive enzymes Occurs in 1--30% older adults
Atrophic gastritis
*Vitamin b-12 transport* -Bound to _____
Bound to transcobalamin II (blood transport protein)
Humans unable to synthesize Vitamin -required dietary intake
C
Vit __ helps maintain collagens 3-D structure by aiding in lysine
C
Vitamin __ synthesizes compounds: -neurotransmitters -hormones -tyrosine -carnitine -conversion of cholesterol to bile acids
C
Functions: Transports fatty acids from cystol to mitochondria for beta-oxidation
Carnitine
Recognized as essential nutrient in 1998
Choline
_____ functions -Component of phospholipids (lecithin) -Homocysteine metabolism -Precursor for acetylcholine (neurotransmitter associated with attention, learning, memory, muscle control) -Component of sphingomyelin (required for myelin synthesis -- protects nerve fibers and facilitates transmission of nerve impulses)
Choline
Can result from inadequate intrinsic factor production and thus inability to absorb sufficient vitamin B-12
Pernicious anemia
-Enhances vitamin b12 absorption -when vitamin b/12____ ____ complex formed, 50% absorption occurs
intrinsic factor
Vitamin b12 storage -can store enough to last several years
liver
____ and ___ damage found in adults fed diets deficient in choline
liver and muscle
Identical to anemia from folate deficiency due to disruption of normal DNA and RBC synthesis
megaloblastic (macrocytic) anemia
UL vitamin b-12
no UL
Choline deficiency
no deficiency disease
_____ may be conditionally essential (for improved fat absorption) for -children with cystic fibrosis -preterm infants
Taurine
Associated with nerve degeneration -- can result in eventual paralysis and death if not treated
pernicious anemia
*Vitamin C storage* -Highly concentrated in ___ and ____ glands, ____, ___ and ____ -low concentrations in ___, ____
pituitary and adrenal glands, WBCs, eyes, brain blood, saliva
Due to impaired synthesis of collagen
scurvy
Symptoms of _____: -fatigue -pinpoint hemorrhages -bleeding gums and joins -impaired wound healing -bone par -fractures -diarrhea -psychological problems -fatal, if untreated
scurvy
Vitamin C deficiency disease
scurvy
____ rare in North america, but poor vitamin C status relatively common
scurvy
Vit C absorption -in ____ _____ Ascorbic acid- ____ transport Dehydroascorbic acid -- ____ transport
small intestine active facilitated
Vit C daily needs higher for
smokers burn and trauma patients
-Does not require intrinsic factor -Small amounts can be absorbed by passive diffusion
supplements form vitamin b12
Abundant in muscle, platelets, nerve tissue; attached to bile acids
taurine
____ functions associated with -nervous system function -platelet aggregation -cell differentiation and growth -photoreceptor activity in eye -antiocidant activity in WBCs and lungs -cardiac contraction -insulin action
taurine
____ sources: -foods of animal origin -synthesized from methionine and cysteine (amino acids)
taurine
Vitamin C excretion
urine
Choline transport
via portal vein to liver
Also known as cobalamin
vitamin b12
contains cobalt as part of structure
vitamin b12
Forms ascorbic acid and dehydroascorbic acid
vitamin c
least stable vitamin easily lost in processing and cooking (40%)
vitamin c
Necessary to maintain normal metabolism -- can be synthesized in body, but biosynthesis at expense of other nutrients (amino acids)
vitamin like compounds (carnitine and taurine)
Needs to increase during times of rapid tissue growth, but deficiencies do not exist in healthy adults
vitamin like compounds (carnitine and taurine)
choline storage
all tissues
Plants do not synthesize vitamin __
b12
Vit b12 excretion Most in ___ Little in ___
bile urine
Functions: Removes excess organic acids produced by mitochondrial metabolism
carnitine
Sources of _____ -animal foods (meat and dairy products) -Liver biosynthesis from lysine and methionone (amino acids)
carnitine
_____ may be conditionally essential for: r-ecovery from disease and malnutrition -serious trauma -cirrhosis -kidney dialysis -preterm birth
carnitine
Dietary needs throughout lifespan unknown is possible requirements may be met by body synthesis alone at various life stages
choline
Not considered a b vitamin
choline
Synthesized in cells, but not enough to support needs -dietary intake necessary
choline
UL based on fishy body odor, low blood pressure, vomiting, GI tract effects, sweating, salivation
choline
____ absorption from from small intestine via trasport proteins
choline
no coenzyme form higher concentrations in body than b vitamins
choline
Sources of vitamin C
citrus fruits, peppers, green vegetables
Consists of 3 polypeptide chains wound in triple helix
collagen
Major fibrous protein that gives strength to connective tissues (tendons, ligaments) found in bone, blood vessels, eyes, skin
collagen
essential in wound healing
collagen synthesis
Not enough evidence to suggest megadoses of vitamin C for prevention of ____ ____
common cold
Choline found in foods as ___ ___ or as part of another compound such as phosphatidylcholine (lecithin)
free choline
Vitamin B-12 factors that decrease absorption -Defective binding of intrinsic factor/vitamin B-12 complex to receptor cells in _____
ileum
Vitamin B-12 factors that decrease absorption -Disease of _____ (crohn's disease)
ileum
Vitamin B-12 factors that decrease absorption -Absense or surgical removal of ____ or ____
ileum or stomach
Vit C UL based on adverse __ effects
GI
Burning, tingling, numbness in legs
Paresthesia
Sources of choline
-animal origin (milk, eggs, chicken, beef, pork) -- large amounts -grains, nuts, vegetables, fruits -- smaller amounts -Lecithins added to food during processing
Major sources vit C contributing to north american diets
-citrus fruits/juices -tomatoes -potatoes -fortified fruit drinks
High risk populations vitamin C deficiency
-impoverished individuals -smokers -alcoholics -individuals with poor diets
Vitamin b-12 absorption from food
-intrinsic factor
Animal products of b12
-meat -poultry -seafood -eggs -dairy products
Two active coenzymes of vitamin b12
-methylcobalamin -5-deoxyadenosylcobalamin
Options to obtain vit b12 for individuals with malabsorption syndromes
-monthly injections to bypass GI tract -use of vitamin b12 nasal gel to bypass GI tract -very high oral doses (1-2 mg/d) -- some passively absorbed
Neurological changes in vit b12 deficiency
-paresthesia -loss of balance, difficulty walking -mental retardation -loss of bowel and bladder control -visual disturbances -GI tract problems
choline excretion -some in ____ -most converted to ____
-urine betaine (methyl donor)
Vitamin B-12 factors that decrease absorption -Absense or defective synthesis of ___-protein, ____ proteases, or _____ factor
-R-protein -pancreatic proteases -intrinsic factor
Vitamin b-12 sources
-Animal products -Fortified foods
Vitamin b12 functions
-Coenzyme methylcobalamin -coenzyme 5-deoxyadenosylcobalamine -both vitamin b-12 and folate involved in conversion of homocystein -> methionine
People at risk for Vit b12 deficiency
-Older americans -Individuals with malabsorption syndromes -vegetarians
Consequences vitamin b12 deficiency
-Pernicious anemia -Megaloblastic anemia -neurological changes -Elevated plasma (homocysteine)
Amount vitamin C above ____ mg/d generally excreted in urine
100
___ mg/d suggested to be highest amount needed to maximize health benefits of vit C
200
Vitamin C UL
2g
Vit C absorption effeciency __-__% between 3--200 mg/d; declines as intakes exceed this amount
70-90
-Risk factor for heart disease and stroke -Associated with cognitive dysfunction, osteoporotic fractures -Supplementation with folate, vitamin B-12, and vitamin B-6 can lower blood
Elevated plasma (homocysteine) Vit b12 deficiency
-Mostly due to atrophic gastritis -not severe enough to produce anemia, but may lead to neurological problems and elevated homocysteine -supplementation or use of fortified foods can help
Older americans (20%)
High doses can give false results for blood in stool
Vitamin C
______ functions include Donates electrons in oxidation-reduction reactions, thus acts as a cofactor for several metalloenzyme Collagen synthesis Synthesis of compounds Antioxidant activity Iron absorption
Vitamin C
Donates electrons to free radicals in vitro (test tube) theorized to act as antioxidant in water-based fluids (e.g. blood) unknown if functions as antioxidant in vivo (in organism)
Vitamin C antioxidant activity
When consumed with meals, modestly facilitates intestinal absorption of non-heme iron by conversion from ferric to ferrous form counter action of some food components that inhibit iron absorption
Vitamin C iron absorption
Not considered to be necessary in diets of healthy people for good health currently included in infant formulas
Vitamin like compounds (carnitine and taurine)
