Vitamin B6, also called pyridoxine, is one of 8 B
vitamins. All B vitamins help the body convert food (carbohydrates) into fuel
(glucose), which is used to produce energy. These B vitamins, often referred to
as B-complex vitamins, also help the body metabolize fats and protein.
B-complex vitamins are needed for healthy skin, hair, eyes, and liver. They
also help the nervous system function properly.
All B vitamins are water soluble, meaning the body does
not store them.
Vitamin B6 helps the body make several neurotransmitters,
chemicals that carry signals from one nerve cell to another. It is needed for
normal brain development and function, and helps the body make the hormones
serotonin and norepinephrine, which influence mood, and melatonin, which helps
regulate the body clock.
Along with vitamins B12 and B9 (folic acid), B6 helps
control levels of homocysteine in the blood. Homocysteine is an amino acid that
may be associated with heart disease. Your body needs B6 in order to absorb
vitamin B12 and to make red blood cells and cells of the immune system.
It is rare to have a significant deficiency of B6,
although studies indicate many people may be mildly deficient, especially
children and the elderly. Certain medications can also cause low levels of B6
in the body. Symptoms of serious deficiency include:
·
Muscle weakness
·
Nervousness
·
Irritability
·
Depression
·
Difficulty concentrating
·
Short-term memory loss
Vitamin B6 and Depression
To understand the importance of B6 to depression, a basic
knowledge of how the brain establishes mood is required.
All neuronal communication in the brain goes through
neurons or nerve cells. This communication flows in the form of signals which
are transmitted in the form of electrical impulses across a synapse to a target
cell by endogenous chemicals known as neurotransmitters. A synapse is the gap
between two nerve cells.
These neurotransmitters carry impulses that are important
for a balanced emotional state as well as form the messengers responsible for
the brain’s ability to control other processes in the body.
Pyridoxal phosphate, its active form of vitamin B6 can
easily cross into the brain. In the brain, it is a coenzyme that plays an
important role in the biosynthesis of the following neurotransmitters:
serotonin, dopamine, epinephrine, norepinephrine and gamma-aminobutyric acid
(GABA).
In the synthesis of GABA, pyridoxal phosphate acts as a
cofactor for the enzyme glutamic acid decarboxylase which catalyzes the
decarboxylation of glutamate to gamma-aminobutyric acid and CO2.
The synthesis of the amino acid, tryptophan to serotonin
also depends on the actions of pyridoxal phosphate.
Of the neurotransmitters listed above, three monoamine
neurotransmitters largely control mood in the brain. The neurotransmitters that
are required in optimal concentrations to improve mood are serotonin, dopamine
and norepinephrine.
Pyridoxal phosphate is also essential in the metabolism
of homocysteine, a non-protein amino acid that is biosynthesized from
methionine by the removal of its terminal methyl group.
Homocysteine is a toxic intermediate of amino acid
syntheses. It is meant as a stopgap between two essential amino acids. However,
the body requires vitamin B6 to convert homocysteine to the next amino acid or
to recycle it back to methionine.
Therefore, high levels of homocysteine can result from
pyridoxine deficiency. The accumulation of this toxic intermediate has been
shown to cause damage to the brain and the heart. In addition, the accumulation
of homocysteine in the brain has been linked to depression.
In summary, low levels of pyridoxal phosphate in the
brain can cause depression by
·
reducing the amount of serotonin, dopamine and
norepinephrine synthesized
·
increasing the concentration of homocysteine
which can cause neurological disorders such as depression
Studies
The National Institute of Health reveals that one of the
symptoms of a vitamin B6 deficiency is depression. A study that took place and was published in
“Psychotherapy and Psychosomatics”, showed that those people who were deficient
in vitamin B6 manifested several symptoms of depression.
Another study published in the Canadian Journal of
Psychiatry further supported the claim that a vitamin B6 deficiency can lead to
mood disorders and depression.
Another important function of Vitamin B6 is to aid in the
production of oxygen-carrying hemoglobin.
A deficiency has been associated with feelings of tiredness and
inattentiveness.
Food Sources of
Vitamin B6
Vitamin B6 can be obtained by eating beef liver,
potatoes, raw garlic and some non-citrus fruits.
Other good food sources of this vitamin would include
bananas, nuts, beans, avocados, fortified breakfast cereals, dried herbs, spices,
salmon, cod and tuna. The key here is to
see to it that you eat a balanced diet every day. Of course, if you do, you
won’t be deficient in any valuable vitamins and minerals. Plus, your depression
symptoms and moods won’t be affected from a B6 deficiency either.
Suggested Dosage
According to the National Institutes of Health (NIH), the
U.S. Recommended Daily Allowance (RDA) for adult males between 19 and 50 years
of age is 1.3 mg, and those over the age of 50 need 1.7 mg. Women between 19
and 50 years of age should take 1.3 mg, and those over 50 should take 1.5 mg.
Pregnant women should take 1.9 mg and lactating women, 2 mg.
Most experts recommend complete B vitamins that include
at least 1000 micrograms (mcg) vitamin B12, 250 milligrams (mg) vitamin B6, and
800 mcg of folic acid every day. Other herbs and supplements for depression, of
course, may also help.
Sources and
Additional Information:
