How Vitamin B6 Works: What It Does in Your Body

Vitamin B6 works as a coenzyme in a vast network of enzymatic reactions — above all in the metabolism of amino acids and proteins, in the conversion of glycogen into usable glucose and in the synthesis of neurotransmitters such as serotonin, dopamine and GABA. It is water-soluble, the body does not store it in large amounts and it needs to be replenished regularly through food. In practice, this means B6 is needed for normal processes to happen — it is not a stimulant and does not produce visible effects in people who already have adequate levels.

This page explains what B6 does, what the research shows (and does not show), how much is usually found in supplements and how to tell whether it makes sense for you. If you want the practical side first, see the vitamin B6 ingredient page.

What is vitamin B6 and in what forms does it exist?

B6 is not a single molecule: it includes three natural compounds — pyridoxine, pyridoxal and pyridoxamine — which the body converts into the active form, pyridoxal phosphate (PLP). It is PLP that acts as a coenzyme, that is, the "piece" that allows many enzymes to do their work. In supplements, the most common form is pyridoxine; pyridoxal-5-phosphate (P5P) also exists, already active, but there is no evidence that it is superior for healthy people.

Because it is water-soluble, the excess is eliminated in urine and intake has to be regular. The trade-off is that very high doses, maintained over time, are not harmless — we come back to this point below.

How vitamin B6 works in protein and energy metabolism

One of the central functions is amino acid metabolism. PLP is a coenzyme of enzymes that transfer amino groups (transamination) and that remove amino groups (deamination), steps needed for the body to use the proteins in the diet and, when necessary, amino acids as an energy source. B6 also takes part in glycogen metabolism, the carbohydrate store in the liver and muscles, and in the conversion of tryptophan into niacin (vitamin B3) — a pathway that links the two vitamins. If you want to understand that other half of the equation, see how vitamin B3 works.

It is worth being clear: B6 does not give an immediate energy boost. What it does is allow metabolism to work as it should. With adequate levels, taking more does not speed up metabolism or burn more calories.

Vitamin B6 and the nervous system: what the science shows

PLP is needed for the synthesis of serotonin, dopamine and GABA, and the conversion of glutamate (excitatory) into GABA (inhibitory) depends on it. This explains the interest in B6 for mood and sensory regulation — but it is worth distinguishing what has been demonstrated from what is merely plausible.

A double-blind trial with 478 young adults compared one month of supplementation with a high dose of B6, a high dose of B12 or placebo: B6 reduced self-reported anxiety and increased visual contrast suppression, a marker of neural inhibition, but did not reliably change the other sensory measures tested ¹. In the same direction, a trial with 300 adults (249 women) found that one month of 100 mg of B6 per day reduced sensory over-responsiveness in participants with high scores on that trait at the start of the study ². These are studies with high doses and specific outcomes — they do not mean that B6 "treats" anxiety or that it produces the same effect in everyone.

The evidence on cognition, however, is weaker: a Cochrane systematic review concluded that there is no proof that B6 supplementation improves cognitive function in healthy adults or in those with cognitive decline ³. And, in a meta-analysis of 10 studies, a higher dietary intake of B6 appeared to be associated with a lower risk of Parkinson's disease, with the authors concluding that dietary intake of B6 exhibited a preventive effect on developing Parkinson's based on the available data ⁴.

Vitamin B6 deficiency: symptoms and who is at risk

The signs of deficiency are non-specific — fatigue, irritability, skin changes — and overlap with those of many other situations, so self-diagnosis is not reliable. Manifest B6 deficiency is uncommon in European populations with a varied diet; in a systematic review of 48 studies on vegan diets, B6 intake did not appear among the nutrients typically lacking, unlike B12, zinc, iodine, vitamin D, calcium, potassium and selenium ⁵.

There are, even so, groups at higher risk: people with intestinal diseases that affect absorption, excessive alcohol consumption and those taking certain medicines. If you suspect a deficiency, the way forward is to talk to a doctor or dietitian and, if necessary, have your blood levels measured — not to start taking doses on your own.

Doses: what the studies say and what the label says

The doses used in research are often much higher than daily requirements — and study doses are not instructions for taking. In the sensory over-responsiveness trial mentioned above, the dose was 100 mg of B6 per day for one month ²; in the anxiety trial, the dose was high, but not specified in the available abstract ¹. For comparison, the Gomas Multivitamínicas da TuttiBear provide 2 mg of vitamin B6 per 2-gummy serving (143% of the reference intake), and the Gomas para o Cabelo e Unhas also 2 mg per 2-gummy serving (143%). In other words, the label is on a very different order of magnitude from the trials — which is relevant for safety, as explained below.

In the available studies, there are no comparisons between gummies and tablets for B6; what is known is that B6 is absorbed in the small intestine and that the pharmaceutical form does not change the nature of the nutrient. If that question is central for you, see vitamin B6 gummies or tablets.

Safety: why high doses of B6 require care

B6 is water-soluble, but that does not make it harmless in high doses. A systematic review of 20 articles describes that high levels of B6 — usually associated with taking supplements — can cause predominantly sensory, axonal-type peripheral neuropathy, with subjective improvement of symptoms after pyridoxine is stopped ⁶. A meta-analysis that brought together 46 observational studies and 7 trials found an association between peripheral neuropathy and low B12 levels, but did not establish a direct causal relationship with low B6 levels ⁷.

The tolerable upper limit revised by EFSA for adults is 12 mg per day ⁸ — far below what was thought a few years ago. The recommended daily allowance for adults is around 1.3 to 1.7 mg ⁹, and most supplements provide between 1 and 2 mg per serving, which stays within safe margins. Do not exceed the recommended doses without professional guidance.

What this means in practice: more is not better. If you take a supplement with B6, respect the dose on the label and do not add several sources together without guidance. If you are pregnant, breastfeeding, ill or taking medicines, talk to a health professional before supplementing. And if you notice tingling or numbness in your hands or feet, stop and seek clinical advice.

In addition, high doses of B6 can interfere with the results of some laboratory tests — inform the laboratory and your doctor if you are taking supplements with B6. And there are medicines with a known interaction, such as levodopa (used in Parkinson's) and cycloserine (an antibiotic): if you take medication, talk to your doctor before supplementing.

B6 in food: where to find it

The preferred route is food. Relevant sources include poultry, fish, potato, chickpeas, banana and fortified cereals. People who regularly eat meat, fish or pulses tend to cover their needs without a supplement. A quick table to guide choices:

Situation	What makes sense
Varied diet, no symptoms	Keep the diet; B6 comes from food
Restrictive diet or compromised absorption	Talk to a professional and assess overall intake, not just B6
Multivitamin supplement with B6	Respect the dose on the label; do not stack products with B6
Questions about symptoms (tingling, persistent fatigue)	Clinical assessment before any supplementation

If you are looking for a multivitamin with B6, you can see the vitamins and immunity gummies or the energy and focus range. For children, supplementation should be decided with the paediatrician — there is context in vitamin B6 for children.

What to expect, in practice

If you have a diagnosed deficiency, correcting it makes a difference and is guided clinically. If you have adequate levels, do not count on perceptible effects on concentration: the available evidence does not show a clear benefit for cognitive function in that situation ³. B6 is a necessary piece of a system that already works — not a switch.

Before buying, check how many milligrams of B6 the daily serving provides and whether you already take other sources. And if your question is about safety at higher doses, there is a dedicated article: is vitamin B6 bad for you?.

Frequently asked questions

What does vitamin B6 do in the body?

It works as a coenzyme in reactions of amino acid and protein metabolism, takes part in glycogen metabolism and is needed for the synthesis of neurotransmitters such as serotonin, dopamine and GABA. It is also needed for the conversion of tryptophan into niacin. Without enough B6, these processes are compromised.

Does vitamin B6 give you energy or improve mood?

It is not a stimulant and does not produce an immediate energy boost. In people with adequate levels, the evidence does not show a clear benefit for mood or cognition. There are trials with high doses that observed a reduction in self-reported anxiety, but in specific contexts and with doses far above those of common supplements.

How much vitamin B6 should I take per day?

The recommended daily allowance for adults is around 1.3 to 1.7 mg and most multivitamins provide 1 to 2 mg per serving. Much higher doses, maintained over time, are associated with peripheral neuropathy. Do not exceed the dose on the label without guidance from a health professional.

What are the symptoms of vitamin B6 deficiency?

They are non-specific: fatigue, irritability, skin changes and, in more severe cases, anaemia or tingling in the hands and feet. Because these signs have many causes, diagnosis requires clinical assessment and, if necessary, blood tests. Do not self-diagnose or start taking high doses on your own.

Does vitamin B6 make you gain or lose weight?

No. B6 takes part in nutrient metabolism, but it does not increase energy expenditure or fat burning. With adequate levels, taking more B6 does not change your weight. Any effect on weight would come from changes in diet and physical activity, not from the supplement.

Can I take vitamin B6 every day?

Yes, within the dose stated on the label of the supplement you choose. Because it is water-soluble, the excess is eliminated in urine, but high doses maintained over time are not harmless. If you take medicines, are pregnant or breastfeeding, talk to a health professional first.