Vitamin B6 is also called pyridoxine, which was previously known as pyridoxol. Your body uses Vitamin B6 to metabolise protein into amino acids and vice versa. Pyridoxine is also a crucial co-factor in most biochemical reactions in the body.

Pyridoxine was grouped as a B-vitamin in 1938 and produced synthetically for the first time in 1939.

The bounded form of this vitamin can be found in the liver, brain, kidney and spleen, although the greatest amount (80 – 90 percent) is stored in the muscle.

Pyridoxine, like all the other B-complex vitamins and vitamin C, is a water-soluble vitamin. The B-complex vitamins are grouped together because of their similar physical properties and their presence in similar food sources.

Because of the close inter-relationship between the B-complex vitamins, it is important to note that the inadequate intake of one of the vitamins can result in the impaired utilisation of the others.

Vitamin B6 is utilised in the body in the form of pyridoxal phosphate (PLP). This coenzyme is an important factor in the metabolism of amino acids, the building blocks of protein. A coenzyme is a compound that plays an important role in the functioning of an enzyme, helping the enzyme to catalyse specific reactions in the body's cells.

For this reason, vitamin B6 enables protein to repair tissue such as muscle. It’s needed to keep your skin, nervous system and brain healthy, and for the formation of antibodies, which help fight infection. It also helps your body produce haemoglobin, the pigment that makes your blood red and which carries oxygen around your body.

Pyridoxine is also necessary for the release of glucose, which makes it an important roleplayer in energy metabolism.

The vitamin also seems to have a stabilising effect on sex hormones, which is why many premenstrual women find it useful.

The vitamin B6 content of foods is expressed in milligrams. It's important to note, however, that the bioavailability of pyridoxine may differ in different foods. "Bioavailability" refers to the amount of the vitamin that is delivered to its site of action in the body.

The recommended daily allowance (RDA) for adults is in the range of 1.3mg to 1.5mg. A meal such as a piece of salmon and a baked potato would contain this amount of vitamin B6. For optimal health, 25-50mg a day is recommended, and taking up to 100mg per day is considered safe.

Women trying to reduce premenstrual symptoms can take elevated levels of pyridoxine with relative safety (see "How much vitamin B6 is too much?").

It's interesting to note that the body's need for vitamin B6 increases as protein consumption increases.

Click here to view a complete list of RDA values for this vitamin.

Vitamin B6 is well distributed in a wide variety of foods. Good sources include meat, whole-grain wheat products, vegetables and nuts. Potatoes, bananas and prunes are fairly good sources.

It's important to note, however, that the pyridoxine available in plant sources often has a low bioavailability (the vitamin is bounded to protein, resulting in the inefficient delivery to its site of action in the body). For this reason, it is better to choose food sources of animal origin if you need to increase your vitamin B6 intake.

Vitamin B6 deficiency is relatively rare, due to the wide distribution of the vitamin in foods. The use of certain medications can result in the ineffective metabolism of the vitamin, which might lead to deficiency.

Anaemia, sleeplessness, irritability, anxiety, dry skin, cracked lips, stress and premenstrual symptoms are all possible symptoms. Deficiency can be reversed by vitamin B6 injections.

People who consume a lot of alcohol, vegans, vegetarians and those on a high protein diet would benefit from increased doses of up to 250mg per day.

If you smoke or drink a lot of soft drinks, it is also a good idea to boost your vitamin B6 intake.

Pyridoxine deficiency is relatively uncommon. It should be noted that extremely high doses can be dangerous.

Interestingly enough, many of the signs of vitamin B6 toxicity resemble the symptoms of vitamin B6 deficiency.

Regular doses seem to be preferable to intermittent large doses, as the body excretes vitamin B6 in the urine just eight hours after it enters the body.

A supplement containing the B-complex vitamins, including vitamin B6, appears to help reduce fatigue.

Vitamin B6 is necessary for the production of the feel-good nerve transmitter serotonin, so taking vitamin B6 seems to help relieve the symptoms of depression.

New research also indicated that vitamin B6, B12 and folate might be especially important in preventing breast cancer among women who drink moderate amounts of alcohol.

Preliminary tests have also indicated that vitamin B6 might play a positive role in heart health.