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What
is it?
Vitamin
B6 is a water soluble vitamin that exists as a family of 3 compounds:
- pyridoxine
- pyridoxal
- pyridoxamine,
and each
has a phosphate derivative
The
general vitamin name is pyridoxine. It performs a variety
of functions in the body and is essential for health.
Functions
- what does it do?
The
coenzymes of vitamin B6 are needed for the activity of several
enzymes involved in carbohydrate, protein, and fat metabolism.
For example, vitamin B6 functions as a coenzyme for glycogen
phosphorylase, an enzyme that causes the release of glucose
stored in the muscle as glycogen.
Amino
amino metabolism.
One of the most important
functions of vitamin B6 is its role in protein metabolism as
the vitamin B6 coenzymes are required to metabolise amino acids.
The coenzymes participate in reactions that allow a cell to
synthesize nonessential amino acids.
Red blood cell
production.
Your body needs vitamin B6 to make haemoglobin. Vitamin B6 functions
as a coenzyme in the production of haeme, a component of haemoglobin.
Haemoglobin within red blood cells is critical for the transport
of oxygen to tissues. Vitamin B6 is able to bind to the haemoglobin
molecule and affect its ability to pick up and release oxygen.
A vitamin B6 deficiency can result in a form of anaemia that
is similar to iron deficiency anaemia.
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Haemoglobin. The
iron containing part of red blood cells that carries oxygen
to cells. |
Nervous
system function. The
synthesis of many neurotransmitters
requires enzymes that uses vitamin B6 as a coenzyme. Neurotransmitters
allow nerve cells to communicate with each other and other cells.
Niacin formation.
Vitamin B6 aids the conversion of the amino acid, tryptophan,
to niacin.
| Neurotransmitter.
A compound made by the nerve cells that allows for communication
between it and other cells. |
Requirements
- How much do we need?
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| |
Recommended
Dietary Allowance*
(mg/day) |
| Life-Stage
(years) |
Males |
Females |
| 0
- 0.5 (0 - 6 months) |
0.1a |
0.1a |
| 0.5
- 1 (7 - 12 months) |
0.3a |
0.3a |
| 1
- 3 |
0.5 |
0.5 |
| 4
- 8 |
0.6 |
0.6 |
| 9
- 13 |
1 |
1 |
| 14
- 18 |
1.3 |
1.2 |
| 19
- 50 |
1.3 |
1.3 |
| Ages
51+ |
1.7 |
1.5 |
| Life-Stage
(years) |
Pregnancy |
Lactation |
| 18
and younger |
1.6 |
1.7 |
| 19
- 30 |
1.6 |
1.7 |
| Ages
31 - 50 |
1.6 |
1.7 |
*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. |
|
Sources
- Where is it found?
|
| Food
Groups |
Food
Sources |
| Nutrient
Density |
| High |
Medium |
Low |
|
| Meat,
poultry, fish, dry beans, eggs, and nuts |
Meat,
Poultry, Fish, Beans, Nuts, Seeds |
| Bread,
cereals, rice and pasta |
Fortified
breakfast cereals, Wheat germ (whole-wheat products) |
| Vegetables |
Potatoes,
Spinach, Cauliflower |
| Fruit |
Avocados,
Bananas, Dates, Cantaloupe, Watermelon |
| Milk,
yoghurt and cheese |
Milk,
Cottage cheese |
| Fats,
oils, and sweets |
|
|
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Deficiency
- When you have too little
Severe deficiency
of vitamin B6 is rare. Alcoholics are thought to be most at
risk of vitamin B6 deficiency, due to low dietary intake, and
alcohol and alcoholic liver disease impairing the metabolism
of the vitamin.
Toxicity
- When you have too much
Although
vitamin B6 is a water-soluble vitamin and is excreted in the
urine, prolonged ingestion of very high dose supplements of
the vitamin may result in nerve damage, which is a disease or
abnormality of the nervous system. Symptoms include pain and
numbness of the limbs, and in severe cases difficulty in walking.
Intakes
of 2 to 6 grams of vitamin B6 per day for 2 or more months can
lead to irreversible nerve damage. Even prolonged intakes of
500 mg per day can have the same effects.
|
Upper
Limit+
(mg/day)
|
| Life-Stage
(years) |
Males |
Females |
| 0
- 0.5 (0 - 6 months) |
ND |
ND |
| 0.5
- 1 (7 - 12 months) |
ND |
ND |
| 1
- 3 |
30 |
30 |
| 4
- 8 |
40 |
40 |
| 9
- 13 |
60 |
60 |
| 14
- 18 |
80 |
80 |
| 19
- 50 |
100 |
100 |
| Ages
51+ |
100 |
100 |
| Life-Stage
(years) |
Pregnancy |
Lactation |
| 18
and younger |
80 |
80 |
| Ages
19 - 50 |
100 |
100 |
| Ages
51+ |
100 |
100 |
| +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. |
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