Vitamin B6 (Pyridoxine): Characteristics and Functions

18 March, 2021
This article has been written and endorsed by el nutricionista Saúl Sánchez
Adequate doses of vitamin B6 could reduce cardiovascular risk from a lower accumulation of homocysteine, a key factor in cardiac risk.

Vitamin B6 has a water-soluble character, which means that it dissolves in water. It is present in many of the foods we consume on a daily basis, and performs similar functions to those of other vitamins in group B. It also has specific tasks, which we will look into in more depth below.

Keep in mind that, in normal conditions, we will ingest this nutrient on a daily basis. Except in the case of very restrictive diets, we normally meet the daily requirements of this substance, and so it’s unusual to find a deficit in people. In addition, this substance’s absorption is hardly affected by fiber intake at all.

Functions of vitamin B6

In addition to participating in certain metabolic reactions, vitamin B6 stands out for its involvement in neurological physiology. This is stated by research published in the journal Medical Hypotheses, where the intake of this nutrient has a connection to relieving the symptoms of autism. It can also be effective in preventing the appearance of other types of pathologies with a nervous component.

On the other hand, pyridoxine is involved in the production of hemoglobin. There is evidence that shows that the deficiency of this substance can produce problems in the synthesis of this molecule, which is responsible for transporting oxygen to cells and tissues via the blood.

A low intake of vitamin B6 could lead to anemia, although this usually happens in very few cases.

Also noteworthy is the importance of pyridoxine in protein breakdown processes. In this way, the higher the protein consumption, the higher the dietary needs of the vitamin will also be, with the aim of breaking it down into amino acids and processing them.

Some experts even assure us that this nutrient could have implications in cancer metabolism, due to the ability to interact with proteins and modulate inflammatory states.

Where can we find vitamin B6?

As we said, having a vitamin B6 deficiency is rare. Why? Because we can find it in all the most commonly consumed foods, such as fish, meat, and vegetables.

Salmon and tuna stand out within the fish group for their rich content in pyridoxine. As does pork and the liver of land animals.

As for vegetables, we should highlight the excellent vitamin B6 content of walnuts and whole grains. It’s even possible to find cereals fortified with pyridoxine, which will increase their nutritional value.

For this reason, except in the case of following an overly-restrictive miracle diet, there should be no danger of a deficiency in this substance which would affect a person’s state of health. However, if this situation should come to pass, then immunological and metabolic alterations could be experienced, as stated in a study published in 2020.

It’s possible that gluconeogenesis (synthesis of glucose within the body) is altered in these cases, thus causing a state of fatigue. This could also cause anemia, as we discussed earlier.

Risk situations

Despite what we said earlier, there are some people who may be more likely not to meet their daily pyridoxine needs. Among them, we should highlight kidney patients who are on dialysis, and patients whose livers aren’t working properly. In both cases, their requirements could be increased.

People with autoimmune diseases may also need higher amounts of vitamin B6. An example would be patients with autism spectrum disorder, although those with rheumatoid arthritis or inflammatory bowel diseases are also likely to be included in this group.

Finally, those who consume alcohol on a regular basis are also at risk of developing a deficit of this nutrient. This occurs because the microbiota is altered when drinking alcohol. For this reason, endogenous production of the substance and the ability of the intestine to metabolize and absorb it decrease.

Man-alcoholic-and-pyridoxine-deficiency.
Alcoholic patients are more likely to develop vitamin B6 (pyridoxine) deficiency.

Symptoms of a pyridoxine deficiency

Since it’s a water-soluble vitamin, you need to guarantee a daily intake, due to the fact that it is continuously excreted through urine. If these requirements aren’t met, then a certain symptomatology may appear.

Among the symptoms that could occur, problems related to the skin are particularly prominent, such as rashes. Cracks in the corners of the lips may also occur, as well as inflammation on the upper part of the tongue.

We should note that depressive processes have also been associated with an insufficient supply of the substance. In the same way, the immune system will be compromised, as shown by this article published in the journal Folia Biologica. The risk of developing certain tumors could also be increased as a result of this situation.

Vitamin B6 supplementation

Experts have put forward that pyridoxine supplementation could be beneficial for our health in certain cases. However, there haven’t been any cases of toxicity due to excessive doses, and so the use of dietary supplements of this vitamin is totally safe.

There is evidence that indicates that the administration of this nutrient, together with other B vitamins, could be effective in reducing the risk of developing cardiovascular diseases. The argument that supports this claim is that high levels of these substances are capable of reducing the accumulation of homocysteine, a key factor in cardiac risk.

However, the research that has been carried out on this is quite limited at the moment, and so it isn’t possible to recommend pyridoxine dietary supplements for this purpose as yet.

A consensus has been reached regarding the use of vitamin B6 supplements with the aim of improving how various neuropsychiatric disorders are managed. An example of this would be autism, where the nutrient may be able to stimulate the patient’s attention.

Pyridoxine requirements

Up to 13 years of age, the daily requirement for pyridoxine is around 1 mg. It’s quite easy to attain this through a varied diet. From the age of 16, there is an increased need for this vitamin, which should then be 1.2 mg daily. Once a person reaches adulthood, the need increases further to 1.5 mg of the nutrient on a daily basis.

You should bear in mind that the risk situations we have discussed increase these figures. It would be necessary to assess each case separately in order to estimate optimal doses, depending on the patient’s situation.

In the case of pregnant women, it may be necessary to ingest 2 mg of the substance on a daily basis.

Toxicity

There really haven’t been many cases of vitamin B6 toxicity. It’s practically impossible to reach toxic limits through our diet, as an adult would have to ingest 100 mg a day.

This could be achieved through the use of supplements, although the recommended doses should be widely exceeded in order to reach such a situation.

However, in the case of pyridoxine poisoning, skin reactions, hypersensitivity to sunlight, nausea, and heartburn may occur. It should be noted that if these high values are maintained in the body in the medium term, disorders in the nervous system could even appear.

Due to the risk of toxicity, it isn’t recommended to use supplements without the supervision of a professional in the field.

Drug interactions

Vitamin B6 isn’t free from drug interactions. Some medications can reduce the circulation of this substance; here we can highlight epilepsy drugs. In these cases, it may be necessary to resort to supplementation, as well as to plan the diet according to individual needs.

On the other hand, it’s also possible to find drugs that are intended to treat pulmonary pathologies that can interfere with the absorption of the nutrient, or reduce its levels. The most typical ones here are drugs prescribed for the management of asthma.

Pyridoxine-drug-interactions
Some medications and drugs for epilepsy can alter blood levels of vitamin B6 (pyridoxine).

Finally, it should be noted that one of the most widely-used drugs in the treatment of tuberculosis can also generate a similar effect.

However, negative interactions between vitamin B6 dietary supplements and other broad-spectrum antibiotics have been reported in some research. With dietary doses, there’s usually no problem at all.

Vitamin B6, a nutrient with many functions

As you have seen, pyridoxine has a whole host of functions in the body. Most of them are important, and may be able to modulate the individual’s state of well-being. A deficit of the nutrient could lead to anemia or nervous disorders. Fortunately, these types of situations are not frequent.

It is relatively easy to reach your daily requirements for vitamin B6. This is because the substance is found in a wide variety of foods. For this reason, it would be necessary to propose a very restrictive diet in order to create a deficit.

Despite everything, there are some people who do require increased doses of this substance. It should also be remembered that, as it’s a water-soluble nutrient, a daily intake must be guaranteed. There are no pyridoxine reserves in the body.

Finally, keep in mind that supplementing with vitamin B6 could generate beneficial effects in the medium term, as long as it’s prescribed by a professional.

These doses make sense when it’s intended to reduce cardiovascular risk in patients with a history of this condition, or for the treatment of certain skin conditions. Whatever the case, experts never recommend prescribing the use of these supplements on a general basis for everyone, as they aren’t usually necessary.