absorption/metabolism Flashcards
how much lipid do you need to absorb A
usually enough in a balanced meal - 3-5g
what impact could a low fat diet have on A status
possible deficiency
how much animal bit A/preformed/retinol is absorbed
70-90% - liver toxicity!
how are provitamin A/carotenes metabolised in small intestine
converted to retinol
are carotenes potentially toxic
no, body regulates
what relationship are carotenes to carotenoids
carotenes are carotenoids
where is A stored
in the liver
what is retinol (alcohol) oxidised to in body
retinal (aldehyde) and retinoid acid (acid)
3 carotenoids that are converted into A
beta-carotene
alpha-carotene
beta-cryptoxanthin
3 carotenoids not converted into A
lycopene
lutein
zeaxanthin (antioxidants)
what are the vitamins of A
retinol
retinal
retinoid acid
b1 absorption inhibited by
alcohol
b1 is lost in your own
sweat/urine
is thiamin stored in your body
v little
What turns urine bright yellow
Excess riboflavin
What is our absorption of riboflavin like
Limited
Impaired by alcohol, antacids etc
What are the cofactor/coenzyme forms of riboflavin that the body can use
FAD
FMN
What is long for FAD
Flavin adenine dinucleotide
What is long for FMN
Flavin mononucleotide
how should you take riboflavin for better absorption
with food
can niacin be synthesised in the body
yes from amino acid tryptophan
how much tryptophan makes 1mg niacin
60mg
what must niacin be converted into for the body to use
coenzyme/cofactor forms:
NADH
NADPH
nicotinamide adenine dinucleotide
and
nicotinamide adenine dinucleotide phosphate are cofactor forms of what
niacin
NADH
NADPH
which effective form of which vitamin can cause a flush
‘flushing’ niacin - flush is good - really works
can niacin be synthesised in the body
yes from amino acid tryptophan
how much tryptophan makes 1mg niacin
60mg
what must niacin be converted into for the body to use
coenzyme/cofactor forms:
NADH
NADPH
nicotinamide adenine dinucleotide
and
nicotinamide adenine dinucleotide phosphate are cofactor forms of what
niacin
NADH
NADPH
which effective form of which vitamin can cause a flush
‘flushing’ niacin - flush is good - really works
2 other forms pyroxidine
pyridoxal
pyridoxamine
all 3 form of pyridoxine converted to
pyridoxal phosphate PLP
two types & long names of vit D
D2 - ergocalciferol
D3 - cholecalciferol
ergocalciferol what source
made from what
plant source
made from steroid
source of cholecalciferol
made from what
source - sun exposure/animal source
made from cholesterol
D2 or D3 more potent
D3 much more potent
is much D stored
v little stored in blood as CALCIFEROL
what must happen to D3/2 so body can use
must be HYDROXYLATED (converted)
which 2 hydroxylations must any D go through
1 - in liver - converts to CALCIDIOL
2 - in kidney - converts to CALCITRIOL
calcidiol long name
25-hydroxyvitamin D3
calcitriol long name
1-25-dihydroxyvitamin D3
which is active form of D
calcitriol
1-25-dihydroxyvitamin D3
2 families of vit E compounds
tocopherols
tocotrienols
E primarily stored where
in cell lipid membranes
and adipose tissue
action of tocopherols and most active
a-tocopherol most active
mainly antioxidants, skin
action of tocotrienols
mainly cholesterol-lowering similar to statin
3 types & long names K
K1 - phylloquinone
K2 - menaquinone
K3 - menadione
K1 source
green leafy veg
K2 source
synthesised in our intestinal bacteria
K3 source
synthetic compound - can be made into K1
how much K1 is absorbed
80%
where is K2 absorbed and how well
partly
into lymphatic system
3 types & long names K
K1 - phylloquinone
K2 - menaquinone
K3 - menadione
K1 source
green leafy veg
K2 source
synthesised in our intestinal bacteria
K3 source
synthetic compound - can be made into K1
how much K1 is absorbed
80%
where is K2 absorbed and how well
partly
into lymphatic system
folate is a family of compounds called
pteroglutamates
the primary active form of folate in the body is
THF - tetrahydrofolate
by how much is synthetic folate more bioavailable than natural folate
1.7 as available
What is added, then removed from folate after absorption
a methyl group (-CH3)
its is removed by B12 - which activates both vitamins