Folate: Its health benefits

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XXVIII
Peer-reviewed article
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Monographic supplement series: DIETARY SUPPLEMENTS: omega-3, proteins, vitamins - AgroFOOD industry hi-tech - July/August 2012 - vol 23 n 4
INTRODUCTION
The preceding part of the article studied the production
method for folates and folic acids and discussed their bio
availability differences. In the following section, it is intended
to discuss the role of folates and folic acid in human health
and the related clinical conditions.
Folate methabolism
F, folic acid is the synthetic form; while DHF and THF
are enzymatically converted to monoglutamates from
polyglutamates for absorption across the small intestine
(Figure 1).
THF. C1- active form of THF that participates in specifi c
reactions- like, methyl- THF for methionine synthesis, formyl-
THF for purine biosynthesis and so on. During methionine
and purine biosyntheses, a single carbon atom is donated
and THF remains unchanged. On the other hand, TMP
formation needs 2 Hydrogen atoms and 1 Carbon atom.
So, the product DHF must be reduced to THF by DHFR to re-
enter the metabolic cycle. Bacteria and lower eukaryotes
cannot take up folates from their environment, but can
biosynthesize folic acid from scratch (1).
HEALTH BENEFITS OF FOLIC ACID
Folates are hydrophilic anionic molecules that do not
cross biological membranes by diffusion, but specialized
membrane transport systems allow folate accumulation
into mammalian cells and tissues (2).
Women’s health
Excretion of folate catabolites in late pregnancy has been
documented as being higher than that in non-pregnant
women. In contrast, in mid pregnancy urinary folate
catabolites were not found to be increased. No differences
were detected in urinary stable-isotope labelled folates or
their catabolites between women in the second trimester
and non-pregnant women.
Folate defi ciency is linked to placental abruption (pre
mature detachment of placenta) due to a weak but
positive association between hyperhomocysteinermia
and risk for placental abruption (3). Recent fi ndings have
indicated that plasma Homocysteine (Hcy) concentration in
women with preeclampsia is higher than in women without
preeclampsia (3, 4). It has been found that maternal use of
folic acid supplements 3 months before becoming aware of
pregnancy and/or during the following
3 months was associated with improved
gross motor development at 3 years of
age in African-American children (5).
Research demands evaluation of
childhood neuro development before
and after the initiation of folic acid
fortifi cation program.
A meta-analysis study has led to the
fact that odds ratios for NTDs increase
as maternal body mass index increases
compared to women with normal
weight (6). A higher risk of NTDs has
been reported with increasing maternal
weight even after folic acid fortifi cation
was initiated (7). A model to evaluate
the association between use of folic
acid and twinning has been proposed
(8), suggesting that the use of IVF is a strong confounder
in this relationship, in turn leading to a possible false
association.
The development and closure of the neural tube are
usually completed within 28 days of post conception. The
Food and Drug Administration mandated that all enriched
cereal grain products contain 140 μg of folic acid per 100
g of grain by January 1998. An 11 to 20 percent reduction
in the occurrence of anencephaly and a 21 to 34 percent
reduction in the occurrence of spina bifi da were observed
when comparing the pre- versus post fortifi cation time
eras (9). It is still unclear as to why a substantial proportion
of women who take folic acid supplements in the
periconceptional period still deliver off springs with NTDs.
It has been demonstrated that women who had off springs
with oral clefts were more likely to report taking a folic acid
antagonist at some time during the second or third month
of pregnancy (10).
Other health benefi ts
Folate Status of Reproductive Age Women and Neural
Tube Defect Risk- The Effect of Long-Term Folic Acid
Shalini S. Arya
Folate:
its health benefi ts
SHALINI S. ARYA*, K. PAVITRA
*Corresponding author
Institute of Chemical Technology, Food Engineering and Technology Department
NM Parikh Marg, Matunga, Mumbai, 400 019, India
Figure 1. Folic acid metabolism (1).

XXIX
Peer-reviewed article
die before maturation and release from the bone marrow.
The MCV may not be increased to more than 100 fL if
fragmentation is severe, but the red cell distribution width
(RDW) will often be very high. The white blood cell and
platelet count may also be decreased in severe cases. As
the anaemia worsens, there may be a release of immature
white blood cells such as metamyelocytes, as well as
myelocytes and nucleated RBCs with megaloblastic
morphology, known as leukoerythroblastic changes, in the
peripheral blood smear.
BIOCHEMISTRY ASPECTS OF FOLATES: FOLATE AND VITAMIN
B12- METABOLIC ASSOCIATION: METHYL FOLATES TRAP
Essentially a deficiency of vitamin B12 produces
megaloblastic anaemia because of its role in folate
metabolism. During the many transformations of folate
from one form to another, a proportion gets accidentally
converted into N5-methyl-tetra hydro folate, an inactive
metabolite. This is called the “folate trap”, since there
is no way for active N5, N10-tetra hydro folate to be
regenerated except through a reaction for which a form
of vitamin B12, methyl-B12, is a cofactor. Deficiency of B12
then produces a situation where more and more folates
are trapped in an inactive form with no biochemical
means of escape. The end result is failure to synthesize
adequate DNA.
FOLATE IN CHEMOTHERAPY
Methotrexate (MTX), the mainstay for the treatment of cancer,
targets primarily DHFR (14). Both agents are able to induce
cell cycle arrest an apoptosis by inhibiting the cell’s ability to
Supplementation at Doses of 140 µg and 400 µg per Day
have been studied (11). The study demonstrated that
although the prevalence of folate deficiency was low,
nearly two-thirds of the study population had baseline
RBC folate concentrations below the level thought to
be protective against NTDs (i.e., ≥906 nmol/L). There was
no evidence that mean RBC folate concentrations were
significantly higher in the group of women taking 400 μg
folic acid/ day as compared to the 140 μg groups.
The serum levels of 25-OH vitamin D, folic acid and testosterone
in patients with breast cancer has been studied (12).
It was found out that Folic acid levels were higher in
the patient group and the difference was statistically
significant (p=0.044). Low levels of folic acid were
detected in the control group. Low levels of folic acid but
high vitamin D and testosterone levels may be protective
against breast cancer.
Folate and vitamin B12 status in schizophrenic patients has
been studied (13). Mean serum cobalamin levels in the
schizophrenic group were higher than controls. This study
showed that folate deficiency is common in schizophrenic
patients, therefore, it is important to pay attention to
folate levels in these patients.
CLINICAL FOLATE DEFICIENCY- MEGALOBLASTIC ANEMIA
Decreased DNA synthesis leads to impaired maturation of
the nuclei of erythropoietic precursors, resulting in larger
than normal red blood cells (RBCs), i.e., macrocytes,
and therefore a gradual increase in the mean cell
volume (MCV). The hypercellular bone marrow with
large erythroblasts with abnormally open, uncondensed
chromatin can suggest a misdiagnosis of acute leukemia in
severe megaloblastic anemia. Many of these megaloblasts

5-FU in treating colon cancer. In the case of cancer treatment,
a study of 71 children with non– B-cell acute lymphocytic
leukaemia receiving high-dose MTX reported that those
who received a low dose of folinic acid had a lower risk of
relapse compared with children receiving a high dose of
folinic acid (18). On the other hand, a clinical trial of adult
patients receiving low-dose MTX for advanced or recurrent
squamous cell head and neck cancer reported that patients
receiving MTX alone had a statistically signifi cant increase in
overall toxicity compared with those receiving folinic acid at
24 hours after initiation of MTX (19). It is not clear whether a
reduction in toxicity may coincide with an abrogation in drug
effi cacy. Administering natural folate metabolites, such as
folinic acid, may enhance the effi cacy of antifolate therapy
while reducing toxicity.
DRUGS INDUCING FOLATE DEFICIENCY
The prevalence of hyperhomocysteinemia or even
megaloblastic anaemia will be dependent on the folate
intake of the individual. The multitargeted antifols used
in cancer chemotherapy, such as pemetrexed, were
associated with severe toxicity until it was demonstrated
that the patients with underlying folate and/ or vitamin B12
defi ciency, demonstrated by hyperhomocysteinemia and/ or
elevated MMA, were at the greatest risk for neutropenia and
mucositis. The drugs are now given with folic acid and vitamin
B12 supplementation, with reduced toxicity.
OTHER NUTRIENT DEFICIENCIES THAT MAY AFFECT DIAGNOSIS
BASED ON HEMATOLOGICAL INDICES
The megaloblastic anaemia of either folate or vitamin B12
defi ciencies is indistinguishable with identical abnormalities,
which can only be distinguished by comparing vitamin or
vitamin dependent metabolite concentrations or the clinical
response to small amounts of individual vitamins. Treatment of
the vitamin B12–defi cient patient with folic acid does not cure
or prevent central nervous system disease; thus, it is important
to either make a specifi c diagnosis or provide long-term
therapy with both vitamins. Vitamin B12 defi ciency anaemia
may occur in persons of normal health on a B12-suffi cient diet
as a result of the autoimmune lack of intrinsic factor, thus
providing a specifi c model for isolated vitamin B12 defi ciency.
In contrast, a common cause of folate defi ciency is alcohol
abuse with its attendant toxicities and multiple nutrient
defi ciencies. Other major causes such as malabsorption and
food deprivation also lead to multiple nutrient defi ciencies.
Sideroblastic anaemia (reduced incorporation of iron into
heme), possibly associated with a defi ciency of pyridoxine
(required for heme synthesis), or toxicity resulting from alcohol
itself, may coexist in about 50 percent of the patients. Iron
defi ciency, characterized by a reduction in MCV, caused
by bleeding or consumption of an iron defi cient diet that is
common in those with alcoholism, will mask the macrocytosis
of folate defi ciency. Likewise, iron defi ciency usually coexists
with folate defi ciency associated with chronic infl ammatory
bowel diseases. The low MCV in thalassemia will increase
with megaloblastic anemia but rarely exceeds 100 fL. Protein
calorie malnutrition may cause serious fat atrophy of the bone
marrow and hypoplasia, which could mask megaloblastic
changes observed in folate defi ciency. Acute bacterial
infections will cause the release of hyposegmented band
forms of neutrophils and can mask hypersegmentation in a
folate defi ciency. Even lack of response to folic acid cannot
be used to rule out folate defi ciency if iron or erythropoietin
defi ciencies coexist.
synthesize DNA and RNA. Folinic acid, a folic acid derivative,
can maintain the vitamin activity of folic acid under MTX
treatment because it does not require DHFR for its conversion
thereby allowing some DNA synthesis to occur in the presence
of DHFR inhibition. Folinic acid is often administered along with
MTX to ‘rescue’ bone marrow and gastrointestinal mucosa
cells from MTX treatment; it is often used in combination with
5-FU in treating colon cancer. Folic acid in vitamin supplements
or food fortifi cation needs to be reduced by DHFR before it can
act as a cofactor. Thus, high folate concentration may result in
up-regulation of DHFR activity, leading to drug resistance (15).
Anti folates for anti-cancer drugs
With the recent approval of two new antifolate drugs for
marketing (Trimetrexate, in the name of Neutrexin, as a
lipophilic inhibitor of Dihydro folate reductase for the life
threatening pneumonia caused by Pnemocystis carinii, and
Raltitexed, marketed as Tomudex, inhibiting thymidylate
synthase for colorectal cancer), anti folate drugs in cancer
therapy have been a recent research high light. The choice
has always been between classical anti folates that are
subject to facilitated transport / polyglutamylation; or
those that are lipophilic, not requiring polyglutamylation
/ transport; or, the least being transport without the need
for polyglutamylation. The current research challenge is to
reduce the toxicity without compromising on potency or
selectivity (16).
Folates can also mediate the delivery of macromolecular
anti-cancer therapeutic agents. Folic acid receptors
prove to be a useful target as they possess properties
as up regulation in most malignant cancers, and
increased density of receptors with advancement
of cancer stages. The basic aspects that are
looked into are the structure and function of
folate receptor, expression of the receptor
in normal and malignant tissues, and the
selectivity of the receptor for tumour cells.
For the folate mediated delivery of these
drugs, some require intra cellular delivery,
such as gene therapy vectors, where
as those as immune therapeutic
agents do not require intracellular
delivery. Full potential of folates
as mediators of anti-cancer
agents can be achieved when
the permeability of tumour is
improved, especially at lower
doses of the therapeutic
agent (17).
Folinic acid, in clinical
practice
Folinic acid, a folic acid
derivative, can maintain
the vitamin activity of folic
acid under MTX treatment
because it does not require
DHFR for its conversion,
thereby allowing some
DNA synthesis to occur in
the presence of DHFR
inhibition. Folinic acid is
often administered along
with MTX to “rescue” bone
marrow and gastrointestinal
mucosa cells from MTX treatment.
Furthermore, folinic acid also
enhances the inhibition of 5-FU on TS;
thus, it is often used in combination with
subject to facilitated transport / polyglutamylation; or
those that are lipophilic, not requiring polyglutamylation
/ transport; or, the least being transport without the need
for polyglutamylation. The current research challenge is to
reduce the toxicity without compromising on potency or
selectivity (16).
Folates can also mediate the delivery of macromolecular
anti-cancer therapeutic agents. Folic acid receptors
prove to be a useful target as they possess properties
as up regulation in most malignant cancers, and
increased density of receptors with advancement
of cancer stages. The basic aspects that are
looked into are the structure and function of
folate receptor, expression of the receptor
in normal and malignant tissues, and the
selectivity of the receptor for tumour cells.
For the folate mediated delivery of these
drugs, some require intra cellular delivery,
such as gene therapy vectors, where
as those as immune therapeutic
agents do not require intracellular
delivery. Full potential of folates
as mediators of anti-cancer
agents can be achieved when
the permeability of tumour is
mucosa cells from MTX treatment.
Furthermore, folinic acid also
enhances the inhibition of 5-FU on TS;
thus, it is often used in combination with

XXXI
by dynamic approaches such as metabolic engineering,
genetic strain improvement, fortifi cation programs and food
augmentation. More research focus is needed on natural
folates and their uses, since metabolism of synthetic folates
is a very individual specifi c process. More focus is required
on processed foods, since food consumption patterns are
no longer region specifi c. Population specifi c studies would
help get a clear picture of folate defi ciency and suitable
approaches must be adopted.
REFERENCES AND NOTES
1. http://users.umassmed.edu/martin.marinus/Mph200/
FolicAcidMetabolism.pdf
2. L. H. Matherly et al., Cancer and metastasis reviews, 26(1), pp.
111-128 (2007).
3. R.P. Steegers-Theunissen et al., Obstetrics and Gynecology, 104,
pp. 336-343 (2004).
4. R.W. Powers et al., Reproductive Sciences, 11, pp. 45-50 (2004).
5. G. Wehby et al., Maternal and Child Health Journal, 12, pp. 80-87
(2008).
6. S.A. Rasmussen, American Journal of Obstetrics and Gynecology,
198, pp. 611-619 (2008).
7. J.G. Ray et a l., Obstetrics and Gynecology, 105, pp. 261-265
(2005).
8. R.J. Berry et al., British Medical Journal, 330, pp. 815-817 (2005).
9. M.A. Honein et al., Journal of the American Medical Association,
285, pp. 2981-2986 (2000).
10. S. Hernandez-Diaz, New England Journal of Medicine, 343, pp.
1608-1614 (2000).
11. N.A. Hursthouse et al., Nutrients, 3, pp. 49-62 (2011).
12. E. Fidan et al., Asian Biomedicine, 5(5), pp. 663-667 (2011).
13. A. Saedisomeolia et al., Journal of Research in Medical Sciences,
16(Special Issue), pp. 437-441 (2011).
14. L. Hu et al., Angewandte Chemie International Edition, 50, pp.
4133-4136 (2011).
15. S. Chattopadhyay et al., Oncologist, 12, pp. 808-815 (2011).
16. A. L. Jackman (ed), Antifolate Drugs in Cancer Therapy (1999).
17. Y. Liu et al., Advanced Drug Delivery Reviews, 54, pp. 674-693
(2002).
18. J. D. Borsi et al., European Journal of Cancer, 27, pp. 1006-1009
(1991).
19. G. Browman et al., Journal of Clinical Oncology, 8, pp. 203-208
(1990).
20. P. Kelly et al., American Journal of Clinical Nutrition, 65, pp. 1790-
1795 (1997).
21. S. Jacob et al., Proceedings of the National Academy of
Sciences, USA. 104(50), pp. 19995-20000 (2007).
CLINICAL CONDITIONS THAT MAY INCREASE CELLULAR FOLATE
REQUIREMENTS
Hemolytic anaemia may cause increased folate utilization.
In addition, it appears that subjects with proliferative skin
diseases such as psoriasis may have hyperhomocysteinemia
and impaired folate status.
Evaluation of hyperhomocysteinaemia shows complex
relationships between age (children vs. adults) and presence
of chronic kidney disease, which develops in many older
patients with sickle cell disease. A combination of folic acid
(700 μg) with vitamin B12 (600 μg) and vitamin B6 (6 mg) was
shown to give a maximum decrease of total Hcy (tHcy) in
patients with sickle cell disease.
The tHcy concentration is elevated in those with chronic
kidney disease and even higher in dialysis patients. During
dialysis, folate and vitamin B6, as well as other water-soluble
vitamins, are lost; thus, it has been common practice to
use a replacement multivitamin, which has been shown to
lower tHcy.
EFFECTS OF EXCESS FOLIC ACID IN BLOOD
Folates are normally non toxic, but excess folates can worsen
the effects of B12 Vitamin defi ciency. It has been concluded
that in Vitamin B12 defi cient patients, levels of homocysteine
and methyl malonic acid are higher in those individuals with
a high blood folate, than in those with normal blood folate
levels (9). Research states that B12 defi ciency is masked only
beyond a blood folate level of 5000 mcg/ day. In adults,
supplemental folic acid should not exceed the UL to prevent
folic acid from triggering symptoms of vitamin B12 defi ciency.
Too much folic acid may interfere with zinc absorption.
The body metabolises PGA into methylfolate, the normal
form of the vitamin transported in plasma. The absorption
and biotransformation process are saturated at doses in the
region of 400 µg PGA or less (20). Thus at doses at or just below
400 µg PGA all the synthetic forms of folate are converted
into biologically active methylfolate during absorption. At
higher doses synthetic PGA is also transported into the blood
in a manner that is directly proportional to the dose. This
raises the possibility of a lifetime’s exposure to unmetabolised
PGA where mandatory fortifi cation is undertaken. Also, it
doubts the increasing tendency among clinicians to give
5 mg doses of PGA (more than 10 times needed to give
maximal methylfolate
concentrations). It
is metabolized by
dihydrofolate reductase,
for which it has a higher
Km (lower affi nity) than
has dihydrofolate itself-
this could have an
antifolate effect through
competitive interaction.
CONCLUSION
The production methods
of folate and folic acid
were analyzed in Part
I. From Parts I and II, it
can be concluded that
folate defi ciency is a
potential clinical issue.
Defi ciency of folate must
be targeted and treated