Folic acid is a term
used to refer to the oxidized form of vitamin B9 found in fortified foods and
in supplements. Folate is a term used to refer to the naturally produced form
of it.
DATS (DIGESTION, ABSORPTION,
TRANSPORTATION AND STORAGE) OF VITAMIN-B9 folic acid
Sources:
The best plant sources of vitamins are leafy green
vegetables as spinach, turnip greens, broccoli, asparagus, mushrooms, dry
beans, peas, potatoes, bread etc. animal sources of this vitamin include milk,
liver, meat etc.
RDA (recommended dietary
allowances):
The recommended dietary allowances are different for the
individuals of different age groups. RDA for males, females and children are:
Gender |
RDA |
Men |
400 micro gram |
Women |
400 micro gram |
Children |
150-200 micro gram |
Functions of vitamin B9 in Human
body:
Vitamin B12 performs many important roles in human body
these are:
- DNA and RNA synthesis.
- Amino acid synthesis.
- New red blood cell formation.
- Purine and pyrimidine synthesis.
- Helps in the development of brain, spinal cord and skeleton in fetus.
- Reduces neural tube defects.
- Enhance immune and nervous function.
DATS (digestion, absorption, transportation and storage) of vitamin B9:
Before the
polyglutamate of folic acid in food is to be absorbed it must need to be
converted into monoglutamate. The hydrolysis and conjugases of polyglutamate
occurs with the help of atleast two foly poly glutamyl carboxy peptidases.
These compounds are present in the pancreatic juice bile and the brush broader
of the jejinal intestinal mucosal cells. These are zn dependent enzymes. These
conjugases converts polyglutamate to monoglutamate stepwise.
Polyglutamate Monoglutamate
This reduced form of folate
is tan absorbed into the intestinal cells. Absorption occurs throughout the
small intestine but majorly in the jejunum. Absorption also occurs through
diffusion. Especially in case of folic acid absorption occurs throughout the
small intestine through diffusion. This is because it is already present in its
reduced form i.e. monoglutamate.
For the transportation of
folic acid and folate transporters are present in the intestinal mucosal cells
and in the blood streams. These transporters are called folate binding
receptors and folate receptors. One of these receptors are in the proximal part
of small intestine which are saturated, dependent on energy, PH and Na+. the
other receptors are RFT (reduced folate transporter) which are present in white
blood cells and other tissues. These transporters bind folate and transport it
towards liver other tissues according to the requirement.
The circulatory form of
folate tetrahydrofolate. That is why folate are immediately converted to
tetrahydrofolate by a stepwise reaction with the help of reductase enzyme. This
tetrahydrofolate can than bind to the receptor. Through one carbon metabolism
this tetrahydrofolate are than utilizes in many reactions.
Folate converts to dihydro folate and dihydro folate tan convert to tetrahydro folate.
The total body levels range from 11-28 mg. about this most of it are stored in liver. Folate is also present in both cytoplasm and mitochondria. Here it act as a co enzyme by accepting and donating one carbon group. The storage form of folate is polyglutamate and 5- methyl tetrahydrofolate.
Interaction with other nutrients:
A synergistic relationship found between vitamin B12 and
folate. Without Vitamin B12 folate cannot donate its methyl group to other
molecules and thus a methyl folate trap occurs.
Megaloblastic anemia and pernicious
anemia (disease caused by Vitamin B9 deficiency):
Deficiency of folic acid leads to macrocytic anemia and
pernicious anemia. Abdominal pain, fatigue, weight loss, sore tongue are the
earlier sign and symptoms of vitamin B9 deficiency. In pernicious and
megaloblastic anemia red blood are large in size than its normal size and are
less in number.
Chemistry of Vitamin B9 in human
body:
THF (tetra hydro folate) acts as a coenzyme in human body in
both mitochondria and cytoplasm. Here it accepts a carbon group produced by the
metabolism of amino acid. The resulting THF than donates this carbon to another
compound for the formation of different substances like purines, pyrimidines
etc.
The accepting carbon group is attached to the N atom at
position 5, 10 or both.
One Carbon Metabolism:
THF
Donors Acceptor
(Serine
( DNA, Purine, Methionine synthesis occurs)
Glysine
Histidine)
THF
Accept methyl,
methylene and formyl
Histidine Metabolism:
Histidine requires THF for its metabolism. Histidine after a
series of reaction converts into formyl. Formyl glutamate by the action of
formylglutamate transferase converts into glutamate. This formyl group
realeases by the formyl glutamate is accepted by THF and it is converted to
5formino tetrahydrofolate.
THF formyl glutamate donates formyl 5 formino THF
This 5 formino THF are than used
for purine synthesis.
in this through one carbon metabolism many compounds are formed in human body.
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