Micronutrition Flashcards
EAR
estimated average requirement, amt of nutrient estimated to meet the needs of 50% of healthy individual in an age and gender group
RDA
recommended daily allowance; two standard deviations above EAR.
suffieint to meet hte
UL
tolerable upper intake level
maximum level of daily intake of a nutrient w/o any health risk
AI
adequate intake; used when evidence is inadequate to set an EAR; approx. of the avg nutrient intake by a healthy pop.
micronutrients include
vitamins and mineral
fat-soluble vitamins
A, D, E, K
water-soluble vitamins
groups of vitamin B’s and vitamin c
macrominerals
Ca2+, Mg2+
trace minerals
iron, iodine, zinc, copper, selenium (chromium, manganese, molybdenum, fluoride, boron)
vitamin that is the exception to dietary insufficiency
vitamin D, can be made in skin when exposed to sun
vitamins are named int he order of
discovery
vitamin A examples
retinol, retinal, and retinoic acid
vitamin A source (non-dietary)
produced from carotenoids, organic pigments in plants
vitamin A function
Δ11-cis-retinal reversibly associates with opsins and functions as light sensor
vitamin A deficiency causes
blindness
retinoic acid function
steroid hormones, regulating cell growth and differentiation
associates w nuclear receptors: retinoic acid receptors (RARs) and retinoid X receptors (RXR)
carotenoids function
antioxidants; may reduce risk of cancers
how vitamin A is stored
in liver and retinol palmitate
dietary sources of vitamin A
dark green and yellow vegetables, liver, egg yolk, butter, and whole milk
vitamin A deficiency prevalence
rare, but 40-60% of Americans consume less than 2/3 of RDA
vitamin D function
steroid hormones maintaining calcium homeostasis
dietary source of vitamin D
synthesized from an intermediate in cholesterol biosynthesis
produced photochemically in the skin
vitamin D deficiency due to insufficient sun
rickets in young children
osteomalacia in adults
dietary sources of vitamin D
vitamin D milk, saltwater fish, liver, and egg yolk
vitamin D synthesis pathway in skin
7-dehydrocholesterol–UV photolysis–> provitamin D3–slow isomerization–>vitamin D3
form of vitamin E in diet
tocopherols and tocotrienols
vitamin E function
antioxidant protecting unsaturated fatty acids
reduce risk of CVD by preventin oxidating of LDL (oxidized form is atherogenic)
where vitamin E accumulates
circulating lipoproteins, cellular membranes, fat deposits
dietary soruces of vitamin E
vegetable oils rich in PUFAs
vitamin E deficiency prevalence
rare
vitamin K functions
post-translation modification of glutamic acid residues to gamma-carboxyglutamic acid residues
blood clotting
bone mineralization
carboxyglutamic acids allow what
proteins to bind to Ca2+
vitamin K and carboxylation rxn
vit K is converted to inactive epoxide form
regeneration of active form requires vit K epoxide reductase
warfarin and vitamin K
anticoagulant, vitamin K antagonist
prevents thrombosis by inhibiting vitamin K epoxide reductase
dietary sources of vitamin K
K1 in green veg
K2 is synthesized by intestinal bacterial
vitamin K deficiency
rare
thiamin function
rapidly converted to thiamin pyrophosphate and thiamin triphosphate
thiamin pyrophosphate funcitons as a cofactor in enzymatic catalysis. thiazole ring forms a carbanion, a strong ncleophile. (ex. pyrvate dehydrogenase)
thiamin triphosphate functions in transmission of nerve impulse in peripheral nerve membranes
thiamin deficiency
severe–>beriberi
chara’d by muscular atrophy and weakness
may occur in populations exclusively relying on polished rice for food or in alcoholics
riboflavin functions
precursor of cofactors used in many redox xns (FAD: flavin adenine dinucleotide; FMN: flavin mononucleotide)
riboflavin deficiency
very rare, usually seen in chronic alcoholics
Sx: angular cheilitis, glossitis, scaly dermatitis
riboflavin sources
milk, meat, eggs, and cereal products
angular cheilitis def
inflamm at the end of lips
glossitis def
inflamm of tongue surface
forms of niacin in diet
niacin (nicotinic acid) and niacinamide (nicotinamide)
function of niacin
converted to cofactors, NAD and NADP:
electron acceptors or hydrogen donors
essential in many redx rxns and celular respiration
NAD is also used for ADP-ribosylation
niacin deficiency
pellagra
Sx: dermatitis, diarrhea, dementia
Rare; primarily seen in alcoholics, pts w severe malabsorption, and elderly on very restricted diets
niacin sources
meats, peanuts, and enriched cereals
pyridoxine
vitamin B6
exists as pyridoxine, pyridoxamine, pyridoxal in diet
Structures for micronutrients!
https://quizlet.com/_32ur3k
cofactor form of vit B6
pyridoxal phosphate
fxn of pyridoxal phosphate
transamination rxn in AA metab
- syn of NTs
- syn of sphingolipids
deficiency of vitamin B6 Sx
mild:
irritability
nervousness
depression
severe:
peripheral neuropathy
connvulsion
sources of vitamin B6
meat
veg
whole-grain cereals
prevalence of vit B6 intake
significant fraction of US pop consumes less than rec intake
another name for Vit C
ascorbic acd
Fxn of Vitamin C
cofactor for several oxidases
- hydroxylation of K and P side chains, necessary for collagen stability
- -proper collagen stability essential for maintenance of CT, wound healing, and bone formation
Vitamin C is a (fxn)
nonenzymatic reducing agent
- aid in abs of Fe by reducing it to Fe2+ in stomach
- protects vit AE and some B vitamins from oxidation
Sx of mild vitamin C def
capillary fragility –>
easy bruising
decr immunocompetence
Sx of severe vitamin C def
scuvy: decr wound healing osteoporosis hemorrhaging anemia
Behavior that increases vitamin C needs
smoking
Use of megadoses of vitamin C to prevent and cure common cold is
controversial
Most abundant mineral in body
calcium
What are fxns of calcium?
bones
2nd messenger
enzyme cofactor
blood coagulation and muscle contractility
How is calcium serum level maintained?
- bones as a reservoir
- diet insuff –> resorption from bones
- vitamin D is req’d for optimal utilization of Ca
- Exercise facilitates Ca2+ use for bone formation
Symptoms of Ca2+ resembles ___
vitamin D deficiency
How to maximize bone density
Ca intake from diet
exercise
How to prevent osteoporosis by micronutrient intake
achieve max bone density (Ca intake) from 10-35 yoa
Mild deficiency of Ca may cause
muscle cramps
Who usually does not consume enough Ca2+?
low income children
adult females
What are dietary sources of calcium?
dairy products
nuts, beans, seeds, seaweeds
Molecules that contain iron
heme, cytochromes, nonheme iron proteins
Fxns of iron
O2 transport
energy metablism
cell proliferation
immune defense
How much more iron do women need compared to men?
2x due to menstruation
How is iron sequestered in the cell?
in ferritin molecules
How is iron sequestered in the blood?
by transferrin molecules
In which groups is iron-deficiency anemia most prevalent?
children
menstruating women
What are the functions of iodine?
synthesis of thyroid hormones
What are food sources of iodine?
seafood:
fish
seaweed
added to table salt
What are the results of iodine deficiency?
goiter: enlargement of thyroid gland
cretinism: severely stunted physical and mental growth
What are functions of zinc?
metalloenzymes
zinc finger proteins
What are the consequences of zinc deficiency in children?
poor growth
impairment of sexual development
What are the consequences of zinc deficiency in general?
poor wound healing
dermatitis
impaired immune function
What is the prevalence of zinc intake?
may be marginal for many individuals
What is the function of copper?
required by many enzymes
ex: lysyl oxidase, which is necessary for collagen cross-linking
What are the consequences of copper deficiency?
anemia
bone demineralization
blood vessel fragility
What is the function of selenium?
incorporated into ~25 selenoproteins in humans
What is the prevalence of selenium deficiency?
rare
How is selenocysteine incorpoated into proteins?
Selenocystyl-tRNA binds to UGA codons in mRNA with a special sequence in 3’-UTR
