Excerpt:

"Folic acid is a water-soluble vitamin known by many other
names--vitamin B9, folate, folacin, and tetrahydrofolic acid. It is
available in fresh leafy green vegetables and liver. Folic acid is also
manufactured synthetically and is included in most multivitamin
supplements. An injectable form is available by prescription.

Folic acid is essential for the formation of the DNA that makes up our
genes and the RNA that transmits their instructions. It is particularly
important in the body's production of red blood cells. Folic acid
deficiency results in megaloblastic anemia, an anemia similar to that
caused by vitamin B12 deficiency. Symptoms include weight loss,
digestive problems, and a burning feeling in the tongue.

Folic acid helps us grow and develop normally. Supplements are used to
treat the anemia that may occur with alcoholism, liver disease,
pregnancy, breastfeeding, or the use of oral contraceptives.

People who do not eat a well-balanced diet, those over the age of 55,
people who abuse alcohol or other drugs, and women who take oral
contraceptives should discuss the need for folic acid supplementation
with their physicians.


Best Dietary Sources

Folic acid is available in green leafy vegetables such as broccoli,
spinach, and romaine lettuce. It is important to note that cooking these
vegetables reduces the amount of folic acid the body receives. Other
natural sources of folic acid include: fruits--especially oranges and
orange juice--calves' liver, brewer's yeast, wheat germ, rice, barley,
beans, peas, split peas, chickpeas, lentils, soybeans, and sprouts."

http://www.mygnp.com/alt_display.asp?mzfile=300390

Central Nervous System (CNS)
****
"Folic acid is found in high concentrations in the CNS where it is
involved in the metabolism (via methylation) of long chain fatty acids
and phospholipids that make neurotransmitters (e.g.: serotonin and
dopamine) and hormones to help regulate brain function, such as mood,
sleep and appetite (Bottiglieri T, 2000).**

It is essential for the proper formation of the brain, spinal cord, and
nerve cells in the embryo, and helps to maintain them in the adult.*
Closure of the neural tube in the fetus during the fourth week of
gestation cannot be completed without it (Northrup H, 2000).* Together
with cobalamin (B12), folic acid helps make the protective myelin sheath
formed by glia cells (oligodendrocytes in the CNS or Schwann cells in
the peripheral nervous system), whose long arms wrap around axons of
nerve fibers allowing nerve impulses to be transmitted (through the
nodes of Ranvier) at phenomenal speeds compared to unmylinated ones."

http://www.i2k.com/~suzanne/page26.htm

Excerpt:

"Health starts with the individual cells of our body. If our cells are
healthy so are we. Healthy cells, in turn, depend on the continued,
faultless replication of our DNA. DNA can be seriously damaged through
attacks by free radicals so an adequate antioxidant status is essential
to cell health. It is now becoming clear though that antioxidants alone
are not enough to protect our DNA; more and more research points to the
B vitamin folic acid as being equally or perhaps even more important in
ensuring proper DNA replication. It is not surprising that a folic acid
deficiency has been implicated in a wide variety of disorders.


Folic acid is essential for the synthesis of adenine and thymine, two of
the four nucleic acids that make up our genes, DNA and chromosomes. It
is now also clear that folic acid is required for the proper metabolism
of the essential amino acid methionine that is found primarily in animal
proteins.


Methionine is converted to homocysteine in the body. Homocysteine, in
turn, may be converted back to methionine in a process requiring folic
acid (tetrahydrofolate) and vitamin-B12 (cobalamin) as a catalyst or it
may be metabolized into cysteine in a process catalyzed by vitamin-B6
(pyridoxine). Cysteine is a vital link in the synthesis of glutathione,
one of our most important antioxidants.

A high blood level of homocysteine has been found to be highly
detrimental to health and is invariably accompanied by a low level of
folic acid(1,2)."

http://vvv.com/healthnews/folic_acid.html

Excerpt:

"Low folate levels, in particular, are also known to result in a poor
response to antidepressants. In a large study, scientists in the UK
looked at the response to the antidepressant fluoxitine in subjects
receiving folate (500ug) and found that
symptoms improved in 94 % of these subjects compared to 61% in a group
receiving a placebo.

These authors conclude that "folic acid is a simple method of greatly
improving the action of fluoxitine and probably other antidepressants".
As severe folate and vitamin B12 deficiencies causes anemia (macrocytic
type), which is easily picked up in a blood test, the question is -
would vitamin deficiencies be detected easily in normal routine clinical
chemistry lab results in major depression? The answer to this appears to
be no, since a recent study has shown that folate and vitamin B12
deficiencies occur in depression, without any evidence of anemia.

The authors go on to suggest that folate and vitamin B12 measurements
should be considered when evaluating resistance to antidepressants. This
finding is just one example of how sub-clinical deficiency can exist and
go unnoticed in routine lab tests. It illustrates how* bioanalysis can
detect sub-clinical deficiencies that ordinary tests fail to pick up.

Clearly nutrition plays an important role in depression and much more
remains to be learned about the role of nutrition in this disorder.
Removing vitamin, as well as mineral deficiencies, and optimizing your
nutritional status could go a long way to removing your risk of
developing depression and in helping to treat the condition."

http://www.balanceyournutrition.com/...depression.htm