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What
is it?
Folate is a general
name used for the water-soluble B-complex vitamin. It includes
folate, which occurs naturally in food, and folic acid, which
is the
synthetic form of the vitamin and is used in vitamin supplements
and fortified foods. Folate gets its name from the Latin
word “folium” for leaf, which relates to the vitamins occurrence
in dark green leafy vegetables.
Functions
- what does it do?
DNA
and RNA Synthesis
Folate
is necessary for the formation of the essential building blocks
of
DNA and RNA.
DNA and RNA are involved in cell division, when a cell divides
and forms 2 new identical copies, and in the transmission of
genes. As folate is necessary for the production and maintenance
of new cells it especially important during periods of rapid
cell division and growth such as infancy and to
make fetal
tissues and organs early
in
pregnancy.
Formation
of Red Blood Cells (Erythrocytes)
Folate
is essential for the formation of both red blood cells (erythrocytes)
and white blood cells in the bone marrow, and for their development.
Folate deficiency greatly affects red blood cell formation.
Amino
acids
Folate
functions as an co-enzyme
in many of the reactions during the
metabolism of amino acids.
| Erythrocytes
are mature red
blood cells. These have no
nucleus and a life span of 120 days. Contains haemoglobin,
which carries oxygen and carbon dioxide |
Requirements
- How much do we need?
|
|
| |
Recommended Dietary Allowance*
(µg/day) |
| Life-Stage
(years) |
Males |
Females |
| 0
- 0.5 (0 - 6 months) |
65a |
65a |
| 0.5
- 1 (7 - 12 months) |
80a |
80a |
| 1
- 3 |
150b |
150b |
| 4
- 8 |
200b |
200b |
| 9
- 13 |
300b |
300b |
| 14
- 18 |
400b |
400b |
| 19
- 50 |
400 |
400 |
| >
50 |
400 |
400 |
| Life-Stage
(years) |
Pregnancy |
Lactation |
| 18
and younger |
600 |
500 |
| 19
- 30 |
600 |
500 |
| Ages
31 - 50 |
600 |
500 |
| DFE
= dietary folate equivalents (1µg DFE = 1 µg of food
folate = 0.5 µg synthetic (supplemental) folic acid on an
empty stomach = 0.6 µg folic acid from fortified food or
supplement consumed with food). Synthetic folic acid is
absorbed more easily than natural food folate. |
|
*The
Recommended Dietary Allowance (RDA) is the average daily
dietary intake level that is sufficient to meet the nutrient
requirements of nearly all (97-98%) healthy individuals
in each life-stage and gender group.
aAdequate Intakes (AI) are used
as no RDA is established. The AI is a recommended daily
intake level based on observed or experimentally determined
approximations of nutrient intake by a group of healthy
people who are assumed to be maintaining an adequate nutritional
state.
bNo data was found thus the EARs and the RDAs
were extrapolated from adult values.
|
|
Sources
- Where is it found?
|
| Food
Groups |
Food
Sources |
| Nutrient
Density |
| High |
Medium |
Low |
|
| Vegetables |
Leafy green vegetables (Spinach, Asparagus, Broccoli, Collards,
Turnip greens) |
| Meat,
poultry, fish, dry beans, eggs, and nuts |
Liver |
| Bread,
cereals, rice and pasta |
Fortified
breakfast cereal, Wheat germ (whole-wheat products) |
| Fruit |
Oranges,
Strawberries, Cantaloupe and other melons |
| Meat,
poultry, fish, dry beans, eggs, and nuts |
Eggs,
Beans, Sunflower seeds |
|
|
Deficiency
- When you have too little
Deficiency
in folate results in poor growth,
megaloblastic
anaemia (and other blood disorders), glossitis (inflammation
of the tongue), and increased levels of homocysteine (an amino-acid
which could increase one's risk for heart disease)
Neural
Tube Defect (NTDs)
Neural
tube defects are birth defects that develop
very early in pregnancy,
between the 17th and 28th day after conception. This is generally
before a woman knows she is pregnant. During this critical time
of pregnancy, the proper formation and closure of the neural
tube, which later becomes the spinal cord, brain, and bone surrounding
the spinal cord and brain, normally takes place. A neural tube
defect occurs when the neural tube fails to close properly.
A
maternal deficiency of folate and a genetic predisposition have
been linked to the development of birth defects, such as neural
tube defects.
The
most common neural tube defects
include:
-
-
spina
bifida
:-
the lower part of the neural tube, which develops into the
spinal cord and the bones that enclose them, does not close
properly, leaving the spinal cord exposed or covered only
with skin
-
anencephaly
:- a fatal condition in which the upper end of the neural tube does not
close and the brain fails to completely develop or is entirely
absent
Other
possible complications in pregnancy.
Limited evidence in humans suggest that deficiency of folate
may be associated with spontaneous abortion and other complications
during pregnancy such as preterm labour and low birth weight
(LBW).
Anaemia
A
deficiency in folate prevents the immature red blood cells
from dividing in the early phases of cell synthesis. The cells
then become progressively larger because they continue to make
protein and other cell components. However the cells produce
insufficient DNA to form two nuclei, due to the folate deficiency,
and as a result the cell cannot divide.
| Megaloblasts
are large, nucleated,
immature red blood cells that results when the cell is unable
to
divide
as it normally should. |
They
then remain as large immature cells, called megaloblasts.
Fewer mature red blood cells (erythrocytes) enter the bloodstream,
which decreases the blood’s oxygen carrying capacity, causing
an anaemia called megaloblastic anaemia. Megaloblasts can develop
into abnormally large red blood cells called macrocytes.
White cell formation
and cell division throughout the body is disrupted, but to a
lesser degree.
Toxicity
- When you have too much
No
toxicity from folate has been reported in adults with daily
doses as high as 15 mg. Although
not toxic to adults, at these high levels, the effects on the
fetus is unknown. The safest during pregnancy is to avoid intakes
greater than 2 1/2 times the RDA.
|
Upper
Limit+
(µg/day) |
| Life-Stage
(years) |
Males |
Females |
| 0
- 0.5 (0 - 6 months) |
ND |
ND |
| 0.5
- 1 (7 - 12 months) |
ND |
ND |
| 1
- 3 |
300 |
300 |
| 4
- 8 |
400 |
400 |
| 9
- 13 |
600 |
600 |
| 14
- 18 |
800 |
800 |
| Ages
19 - 50 |
1000 |
1000 |
| >
50 |
1000 |
1000 |
| Life-Stage
(years) |
Pregnancy |
Lactation |
| 18
and younger |
800 |
800 |
| Ages
19+ |
1000 |
1000 |
| |
| DFE
= dietary folate equivalents (1µg DFE = 1 µg of food
folate = 0.5 µg synthetic (supplemental) folic acid on an
empty stomach = 0.6 µg folic acid from fortified food or
supplement consumed with food). Synthetic folic acid is
absorbed more easily than natural food folate. |
| |
| +Upper
Limits (UL) = The maximum level of daily nutrient intake
that is likely to pose no risk of adverse effects. Unless
otherwise specified, the UL represents total intake from
food, water, and supplements.
ND = Not
determinable due to lack of data of adverse effects in
this age group and concern with regard to lack of ability
to handle excess amounts. Source of intake should be from
food only to prevent high levels of intake. |
|