Vitamin B6 in Athletes: What Pyridoxine Does to Your Blood Work, Energy, and Recovery
Table of Contents
Key Takeaways: Vitamin B6 in Athletes
- Vitamin B6 is essential for metabolism, but clinically significant deficiency is uncommon in well-nourished athletes eating a varied diet.
- More than 90% of strength and speedpower athletes in one study fell below a whole-blood comparison value used for untrained individuals, but this should not be interpreted as proof of clinical B6 deficiency.
- Plasma PLP is the standard marker for vitamin B6 status; it should not be directly compared with whole-blood B6 values used in some athlete studies.
- Vitamin B6 is involved in glycogen metabolism, amino acid metabolism, and neurotransmitter synthesis, but direct evidence that routine B6 supplementation improves athletic performance is limited.
- Exercise can affect vitamin B6 balance and acutely raise plasma PLP, so testing immediately after intense training may overestimate resting status.
- For most athletes, food-first is enough. Supplementation is mainly relevant when intake is restricted, malabsorption is present, alcohol use is significant, or blood work confirms low status.
- More is not better: excessive B6 from supplement stacking can increase the risk of peripheral neuropathy, and total intake should be checked against the EFSA upper limit of 12 mg/day.
Introduction: Vitamin B6 in Athletes
Vitamin B6 plays a fundamental role in human metabolism. It participates in a wide range of physiological processes throughout the body, and true deficiency can produce diverse clinical manifestations, including anemia, dermatitis, and oral or mucosal symptoms. At the same time, the clinical reality is important to keep in perspective: in Western healthcare settings, clinically significant vitamin B6 deficiency is uncommon, and most people obtain enough through a normal diet.
From my own perspective as a physician, this is one of those situations where physiology and day-to-day clinical practice can look quite different. During more than a decade of medical work, I personally have not encountered a clear case of clinically significant vitamin B6 deficiency. That does not mean it never occurs, but it is usually associated with selected situations such as malnutrition, malabsorption disorders, chronic alcohol misuse, or other conditions that substantially impair nutritional status.
Athletes, however, are an interesting subgroup because their nutritional demands and blood work interpretation do not always follow the same assumptions as the general population. More than 90% of strength and speedpower athletes in one study did not attain the reference value (0.88 nmol/mL) for untrained individuals in vitamin B6 whole blood concentration [1]. This does not mean that most athletes have clinically obvious B6 deficiency, but it does suggest that vitamin B6 status may deserve more attention in selected athletic populations.
Vitamin B6 is mechanistically involved in glycogen metabolism, amino acid turnover, and neurotransmitter synthesis. Pyridoxal 5′-phosphate (PLP) — the active form of the vitamin — acts as a coenzyme in over 150 enzymatic reactions [2], is covalently bound to muscle glycogen phosphorylase [3], and is required for the synthesis of key neurotransmitters including serotonin and dopamine [4][6].
In this article I cover the prevalence data, physiology, what exercise does to vitamin B6 status, how to interpret your blood results, and the safety consideration every athlete supplementing B6 needs to know.
Vitamin B6 Deficiency in Athletes: Prevalence and Who Is at Risk
The most direct evidence of vitamin B6 inadequacy in athletes comes from a study of 57 strength and speedpower athletes. The absolute vitamin B6 intake in more than 30% of the athletes was below the German recommended dietary allowance (GRDA), and, in relation to protein intake (GRDA 0.20 mg vitamin B6/g protein), more than 60% of the athletes had values below the GRDA. More than 90% of the athletes did not attain the reference value (0.88 nmol/mL) for untrained individuals in vitamin B6 whole blood concentration [1].
However, the 0.88 nmol/mL value requires careful interpretation because it is easy to misunderstand what it actually represents. The study used this as a reference value for whole blood vitamin B6 concentration in untrained individuals, but the available data do not clearly establish whether this represented a population mean, median, laboratory cut-off, or another derived reference metric [1]. Therefore, it should not automatically be interpreted as a clinical deficiency threshold.
Importantly, this measurement also differs from the marker commonly used in clinical practice. The 0.88 nmol/mL value referred to total vitamin B6 measured in whole blood, whereas clinicians typically assess vitamin B6 status using plasma pyridoxal 5′-phosphate (PLP), the active circulating form of vitamin B6 [3]. Plasma PLP thresholds therefore represent a different measurement from a different sample type and should not be directly compared [3].
Therefore, a more accurate interpretation is that many athletes in this study had lower whole-blood vitamin B6 concentrations than the non-athletic comparison value used by the investigators, rather than assuming that more than 90% had clinically significant vitamin B6 deficiency [1].
Most studies report that male athletes have adequate dietary intakes of vitamin B6, whereas some females, especially those with low energy intakes, appear to have low vitamin B6 intakes [5]. Athletes with low energy intakes are at particular risk, because vitamin B6 is a water-soluble vitamin with limited body stores, and a persistent caloric shortfall may reduce daily intake unless the diet is carefully planned [5]. Athletes already managing low energy availability should consider vitamin B6 in athletes as part of the same nutritional picture as iron status.
Beyond elite sport populations, in developed countries such as Germany, the United Kingdom, and the Netherlands, 5–25% of the male population does not meet the recommended B6 intakes (1.2–1.5 mg/day for men and women from 19 to 50 years old), and marginal B6 deficiency (plasma PLP: 20–30 nmol/L) appears to be more common worldwide than severe deficiency [2].
Importantly, even though some athletes in the study had vitamin B6 intakes below the recommended level and whole blood vitamin B6 concentrations below the comparison value used for untrained individuals, this does not automatically mean they had clinically significant vitamin B6 deficiency. In real clinical practice, overt vitamin B6 deficiency is difficult to prove and rarely ends up being the final explanation for reduced athletic performance, fatigue, or poor recovery.
Part of the reason is simple: clinically meaningful vitamin B6 deficiency appears to be uncommon in well-nourished Western populations. Another part is practical. Vitamin B6 is not routinely tested in standard blood panels, and even if a marginal deficiency existed, it would often be missed unless there was a specific reason to look for it. In most athletes presenting with low performance, fatigue, or slow recovery, more common explanations — such as low energy availability, iron deficiency, insufficient carbohydrate intake, poor sleep, overreaching, illness, or excessive training load — are usually more likely.
This is why I interpret the study cautiously. It suggests that vitamin B6 status may deserve attention in selected athletes, especially when dietary intake is low relative to protein intake. But it does not prove that B6 deficiency is a common clinical diagnosis in athletes, nor that it is usually the main driver of performance problems.
What Vitamin B6 Does in the Athletic Body
Pyridoxal 5′-phosphate (PLP) is the most active form of vitamin B6 and acts as a coenzyme in over 150 reactions. These include the synthesis, transformation, and degradation of amino acids; the provision of one-carbon units; trans-sulfation; synthesis of tetrapyrrolic compounds, polyamines, and hydrogen sulfide (H2S); biosynthesis and degradation of neurotransmitters; as well as glycogen breakdown [2].
Vitamin B6, Glycogen, and Energy Metabolism in Athletes
The body stores of vitamin B6 have been estimated to be approximately 1000 µmol (170 mg), of which 80–90% is found in the muscles, where PLP has a covalent bond to glycogen phosphorylase [3]. PLP serves as a cofactor for glycogen phosphorylase, the enzyme crucial for muscle glycogenolysis, which releases glucose-1-phosphate from glycogen to provide additional glucose during exercise [2]. Because PLP is required for glycogen phosphorylase activity, inadequate B6 status could plausibly affect glycogenolysis, although direct performance evidence in athletes is limited.
Understanding that most of the body’s vitamin B6 is physically embedded in muscle tissue — not circulating freely — also explains why plasma PLP may not capture every aspect of tissue-level B6 status.
Vitamin B6 and Protein Metabolism in Athletes
The link between protein intake and vitamin B6 requirements is well established [1]. During exercise, gluconeogenesis involves the breakdown of amino acids to provide energy to the muscle and the conversion of lactic acid to glucose in the liver — processes that depend on PLP-dependent enzymes [2]. The GRDA is set at 0.20 mg vitamin B6 per gram of dietary protein [1] — which is why the prevalence of vitamin B6 inadequacy rises sharply when assessed relative to protein intake rather than absolute daily intake.
Vitamin B6 and Neurotransmitters in Athletes
Aromatic-L-amino acid decarboxylase is dependent upon the coenzyme pyridoxal 5′-phosphate (PLP), a form of pyridoxine, and therefore serotonin production is metabolically dependent on BH4 and vitamin B6 [4]. The same PLP-dependent enzyme catalyses the final stage in the production of the neurotransmitters dopamine and serotonin [6]. Whether marginal vitamin B6 status in athletes meaningfully affects mood or sleep has not been directly demonstrated; however, the mechanistic dependence of these pathways on PLP makes this a plausible area of concern during high training load periods.
From a practical clinical perspective, this is also where physiology and real-world medicine can diverge. Although vitamin B6 plays an important role in metabolism — including amino acid metabolism and pathways relevant to energy production — I do not routinely recommend vitamin B6 supplementation for athletes or for the general population.
In my view, there is often a tendency to assume that if a vitamin is biologically important, taking more of it must provide additional benefit. In reality, that is not how nutrition usually works. For individuals eating a normal, balanced diet, there is generally no evidence that routinely adding extra vitamin B6 improves health or performance.
However, patients with confirmed deficiencies, malabsorption disorders, chronic alcohol misuse, certain medical conditions, or specific physiological states such as pregnancy represent a different category and may require targeted supplementation. But for most healthy athletes eating a varied diet, routine vitamin B6 supplementation is usually unnecessary.
If I had to choose one supplement that I discuss far more frequently in a country like Finland, it would be vitamin D. Northern latitude and seasonal variation make that conversation much more relevant in everyday clinical practice than vitamin B6.
What Exercise Does to Vitamin B6 Status
The physiological relationship between exercise and vitamin B6 in athletes is bidirectional — and misunderstanding it is the most common reason for misinterpreting B6 blood tests.
During acute exercise, PLP concentrations significantly increased during exercise (P < 0.0001), with 79% of the rise in PLP concentration occurring within 5 min [7]. This rapid rise is thought to reflect mobilisation of PLP from muscle stores rather than an improvement in overall vitamin B6 status [3]. A plasma PLP sample taken immediately post-exercise may therefore overestimate resting levels.
Endurance exercise can acutely affect B6 balance. There was a mean loss of about 1 mg vitamin B6 as a result of the marathon race in a study of 13 endurance athletes [8]. Given that the standard RDA for vitamin B6 is approximately 1.3 mg/day for adults, athletes who compete frequently or accumulate high training volumes may have increased needs, although this should be evaluated on an individual basis.
Even though exercise can affect vitamin B6 balance, this should not be overinterpreted. In practical clinical terms, exercise-related B6 loss is usually not enough on its own to cause clinically significant vitamin B6 deficiency in someone eating a reasonably normal diet.
If an athlete truly has vitamin B6 deficiency, I would first look for another explanation than exercise: malnutrition, very low energy intake, malabsorption, chronic alcohol misuse, or a highly restricted diet. In other words, training may increase nutritional demand, but sport alone is unlikely to create clinically meaningful B6 deficiency if overall nutrition is adequate.
This is an important distinction. Athletes do not need to fear that ordinary training will “drain” their B6 stores into deficiency. The more useful question is whether the athlete’s diet, energy availability, gut health, alcohol intake, or supplement use creates a reason to test or intervene.
How to Optimise Vitamin B6 in Athletes: Test Results, Diet and Supplementation
If vitamin B6 status is measured, the standard marker is plasma pyridoxal 5′-phosphate (PLP), the biologically active circulating form of vitamin B6. In everyday clinical practice, this is not ordered nearly as routinely as hemoglobin, ferritin, or vitamin B12; in my experience, it appears more often in research, specialized nutritional assessment, metabolic evaluation, or selected cases involving malabsorption or suspected deficiency.
Furthermore, plasma PLP should not be confused with the whole-blood vitamin B6 concentration used in some athlete studies. These are different measurements and cannot be directly compared.
A plasma PLP of 30 nmol/L is the conventional sufficiency threshold. However, the metabolic marker for vitamin B6 status — the HK ratio (HKr) — starts to increase already when plasma PLP falls below 100 nmol/L and increases more steeply below 50 nmol/L, indicating biochemical deficiency [3]. This raises a clinically important point: a plasma PLP concentration of 30 nmol/L may be too low as a marker for an adequate vitamin B6 status [3].
Dietary Sources of Vitamin B6 for Athletes
From a practical perspective, this is where I think the message becomes much simpler than the underlying biochemistry. For the vast majority of athletes and patients I see, I am generally not worried about vitamin B6 intake itself. If someone is eating a reasonably normal and varied diet — and not following a highly restrictive or chronically low-energy diet — there is usually no reason for me to suspect inadequate vitamin B6 intake.
Rich food sources of vitamin B6 include poultry, salmon, tuna, beef liver, chickpeas, potatoes, and bananas. The bioavailability of vitamin B6 is estimated to be greater than 75% from food in a mixed Western diet and greater than 90% from supplements [3]. Plant-derived pyridoxine-glucoside — present in legumes and some vegetables — has lower bioavailability, a relevant consideration for athletes following plant-forward diets.
High protein intake drives proportionally higher vitamin B6 needs, at 0.20 mg per gram of dietary protein [1]. In theory, athletes consuming high protein intakes (such as 150–200 g/day) may need to ensure their vitamin B6 intake scales accordingly. This is a consideration that standard RDA values, which are based on the general population, may not fully address in athletes with high protein consumption.
Personally, I tend to look at the bigger picture first. Assuming there is no significant malabsorption disorder, severe nutritional imbalance, chronic alcohol misuse, or another specific condition affecting nutritional status, I would generally expect dietary intake alone to provide sufficient vitamin B6. In my experience, the issue is much more often overall nutritional quality and energy availability rather than isolated vitamin B6 deficiency itself.
Supplementing Vitamin B6 in Athletes: The Safety Ceiling
In most cases, I do not think routine vitamin B6 supplementation is necessary. A healthy person eating a reasonably normal and varied diet should generally obtain enough vitamin B6 from food alone. This is especially true if there is no malabsorption disorder, chronic alcohol misuse, severe dietary restriction, or other medical reason to suspect deficiency.
However, supplementation can be reasonable in selected situations. When blood work confirms suboptimal plasma PLP levels or dietary intake is consistently inadequate relative to protein intake and training load, targeted supplementation may be appropriate. A narrative review of vitamin supplementation in sports also concluded that dietary optimisation should remain the primary strategy, with supplementation serving as an adjunct when intake is insufficient [10].
The safety ceiling for vitamin B6 in athletes deserves explicit attention. The relationship between excess vitamin B6 intakes and the development of peripheral neuropathy is well established [11]. Following a systematic review, the European Food Safety Authority (EFSA) established a tolerable upper intake level (UL) of 12 mg/day for adults, based on a reference point of 50 mg/day from a case–control study [11]. Higher vitamin B6 levels, which usually occur following the taking of nutritional supplements, may lead to the development of a predominantly, if not exclusively, sensory neuropathy of the axonal type [12]. After pyridoxine discontinuation, such patients subjectively report improved symptoms [12].
I also think this is an important point because many patients assume that a water-soluble vitamin cannot really be overdone. I understand the logic: if the body does not store it in the same way as fat-soluble vitamins, it can feel safer. But vitamin B6 is actually one of the clearest examples where that assumption can become misleading.
In athletes especially, there can be a tendency to try to “optimise” everything just in case. Someone may take a multivitamin, a B-complex, a pre-workout, and perhaps a recovery product without really realizing that several of them contain vitamin B6. In my experience, the issue is almost never food itself — it is supplement stacking.
Athletes using multiple supplements simultaneously may unknowingly accumulate high total vitamin B6 intake. Many pre-workout formulas, B-complexes, and multivitamins contain 10–50 mg of vitamin B6 per serving — doses that can individually approach or exceed the EFSA tolerable upper intake level of 12 mg/day [11]. Because of that, I think it is sensible to occasionally look at the combined daily intake rather than assuming that each product in isolation is harmless.
This is why I generally do not recommend trying to maximise vitamin B6 intake. More is not automatically better. Excessive B6 intake can cause harm, and the main concern is peripheral neuropathy — typically symptoms such as tingling, numbness, burning sensations, or altered sensation in the hands and feet. I think vitamin B6 is best approached as something to keep adequate, rather than something to push as high as possible.
Conclusion: Vitamin B6 in Athletes
Vitamin B6 is biologically important, but that does not automatically make it a supplement priority. For most healthy athletes eating a reasonably varied diet, clinically significant vitamin B6 deficiency is unlikely, and routine supplementation is usually unnecessary. In practice, I would usually look first at more common explanations for fatigue, poor recovery, or reduced performance: low energy availability, inadequate carbohydrate intake, iron deficiency, poor sleep, illness, or excessive training load.
The main value of understanding vitamin B6 is not to encourage athletes to take more of it. It is to interpret the science with proper context. Vitamin B6 is involved in glycogen metabolism, amino acid metabolism, and neurotransmitter synthesis, but low values in athlete studies do not automatically equal clinical deficiency. If vitamin B6 status is measured, plasma PLP is the most useful marker, and results should be interpreted alongside diet, protein intake, training load, and the broader clinical picture.
For me, the practical message is simple: keep vitamin B6 adequate, do not try to maximise it. Food should be the foundation. Testing or supplementation may be reasonable in selected cases, especially with restricted intake, malabsorption, chronic alcohol misuse, or confirmed low PLP. But the bigger everyday risk is often the opposite — athletes stacking B-complexes, multivitamins, and pre-workouts without realising how much B6 they are taking. Because excess vitamin B6 can cause peripheral neuropathy, total supplement intake should be checked against the EFSA upper limit of 12 mg/day.
References
[1] https://pubmed.ncbi.nlm.nih.gov/8157861/
[2] https://doi.org/10.3390/ijms25189962
[3] https://doi.org/10.29219/fnr.v67.10259
[4] https://www.ncbi.nlm.nih.gov/books/NBK545168/
[5] https://pubmed.ncbi.nlm.nih.gov/8054964/
[6] https://pubmed.ncbi.nlm.nih.gov/20403077/
[7] https://pubmed.ncbi.nlm.nih.gov/8092090/
[8] https://pubmed.ncbi.nlm.nih.gov/8054960/
[10] https://doi.org/10.3390/nu18020213
