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)