What is Vitamin B6?
Vitamin B6 is a water-soluble vitamin known as pyridoxine. The active coenzyme forms of vitamin B6 are called pyridoxal 5 phosphate (PLP) and pyridoxamine 5 phosphate (PMP). Vitamin B6 performs a wide variety of functions throughout the body in these active coenzyme forms. It is involved in over 100 enzymatic reactions, many of which are a component of protein metabolism and to a lesser degree in carbohydrate and fat metabolism. Vitamin B6 is necessary for hemoglobin formation, immune health, nucleic acid production, homocysteine and glucose regulation, and energy production.1
Much of this article focuses on the function of vitamin B6 in mental health. Vitamin B6 is required for the body to produce many neurotransmitters, including GABA, serotonin, dopamine, epinephrine and glycine. Vitamin B6 is therefore critical for normal cognitive function and mood, as these neurotransmitters help calm, focus, and provide the sensation of pleasure in the human body. Vitamin B6 is also involved in tryptophan metabolism, and deficiencies in vitamin B6 can lead to an increase in neurotoxic kynurenine pathway metabolites. The complexities of the kynurenine pathway are beyond the scope of this article, but it should be noted that many naturopathic doctors do evaluate kynurenine pathway metabolites in their patients with autism and ADHD.
How much vitamin B6 does my child need each day?
The RDA (Recommended Daily Allowance) for vitamin B6 is as follows:
Food Sources of Vitamin B6
Vitamin B6 can be found in many foods of both plant and animal origin. Pyridoxine is the form found exclusively in plant foods and comes from whole grains, potatoes, bananas, nuts and seeds. Pyridoxal is mostly found in animal products and comes from beef, fish, chicken and pork. The vitamin B6 found in plant foods is slightly less bioavailable than the vitamin B6 consumed from animal products. Some rich sources of vitamin B6 are:
- Chicken and Turkey
- Fish, especially Tuna and Salmon
- Winter Squash
- and most fruits, except citrus fruits
What are the signs of vitamin B6 deficiency?
A vitamin B6 deficiency on its own is quite rare, but may occur with a general B-complex deficiency.1 The symptoms associated with a vitamin B6 deficiency include microcytic anemia, dry, cracked and scaly lips and corners of the mouth, swollen tongue (glossitis), fatigue, and rash on the face, neck and shoulders. More severe symptoms like depression, confusion, poor immune function, and peripheral neuropathy may occur after a prolonged deficiency. It can take months for a mild B6 deficiency to result in symptoms. Infants with a vitamin B6 deficiency may show signs of irritability, poor hearing, or in rare instances, seizure activity. Since vitamin B6 is water soluble, conditions associated with fluid balance like renal disease or alcoholism can contribute to a vitamin B6 deficiency. Malabsorption conditions like Inflammatory Bowel Disease and celiac disease reduce the absorption of vitamin B6 and can lead to a deficiency. In addition, antiepileptic drugs lead to a vitamin B6 deficiency over time and children on these medications should be supplementing appropriately under the care of a physician.1
This article focuses largely on the neurological effects of vitamin B6. Even suboptimal levels of vitamin B6 may cause neurological complications in certain susceptible individuals. These neurological signs may include:
- Neuropathy: Vitamin B6 plays a role in the formation of myelin, a protective sheath that surrounds nerve cells. A deficiency of vitamin B6 can lead to the formation of abnormal myelin, which can cause neuropathy, a condition that leads to numbness, tingling, and weakness in the limbs.
- Depression and anxiety: Vitamin B6 is required for the production of serotonin, a neurotransmitter that regulates mood, sleep, and other functions. Low levels of vitamin B6 can lead to a decrease in serotonin levels, which can cause symptoms of depression and anxiety.
- Confusion and irritability: Vitamin B6 is required for the production of GABA, a neurotransmitter that regulates the activity of nerve cells in the brain. Low levels of vitamin B6 can lead to a decrease in GABA levels, which can cause confusion, irritability, and other neurological symptoms.
- Seizures: Vitamin B6 is required for the production of neurotransmitters such as GABA and Glutamate, which play a role in regulating the activity of nerve cells in the brain. Low levels of vitamin B6 can lead to an imbalance in these neurotransmitters, which can cause seizures.
It’s worth noting that these neurological effects can be caused by other conditions or deficiencies as well, and low vitamin B6 is just one of the possible causes. It’s important to see a healthcare professional to rule out other causes and to confirm a diagnosis of deficiency.
Vitamin B6 Toxicity: what are the dangers of taking too much vitamin B6?
Vitamin B6 toxicity from food sources has not been reported. However, prolonged supplementation with high doses (more than 200 mg daily) can cause severe sensory neuropathy that results in a progressive loss of body control. Usually, these symptoms disappear once supplementation is stopped. Other symptoms of vitamin B6 toxicity are skin lesions, headaches, sensitivity to light, and gastrointestinal symptoms like nausea and heartburn. There has been some concern regarding vitamin B6 supplementation during pregnancy, but a recent large study found no association between supplementation and congenital defects in the offspring.1 Individuals with Parkinson’s who are taking L-dopa should not take supplemental vitamin B6.
Due to the risk of sensory neuropathy, the upper limits for food and supplemental intakes are as follows:
What is vitamin B6 used for? How can it be used in children and teens?
Vitamin B6 for PMS (premenstrual syndrome)
Some studies show vitamin B6 supplements to be effective at reducing the symptoms associated with premenstrual syndrome (PMS). A recent clinical trial found that 80 mg of pyridoxine taken across three cycles was found to significantly reduce PMS symptoms such as moodiness, forgetfulness, bloating, and anxiety. The most significant effect was on reducing anxiety, likely due to the role of vitamin B6 in neurotransmitter synthesis. In adolescents, vitamin B6 may be beneficial in easing symptoms associated with PMS following menarche. Although there is some evidence supporting supplementation of vitamin B6 for PMS, more studies would be useful for determining the appropriate dose and duration.2
Vitamin B6 and magnesium for Autism Spectrum Disorder (ASD)
Some studies show speech and language improvements after administering large doses of vitamin B6 to children with Autism Spectrum Disorder (ASD).3 Unfortunately, large doses of vitamin B6 can generate undesirable side effects such as irritability and hypersensitivity to sound. This is where magnesium comes in! Magnesium supplementation may help quell the irritability and hypersensitivity due to its neuro-calming effect and ability to help breakdown stimulating neurotransmitters. Therefore, the combination of vitamin B6 and magnesium may be useful for improving some of the characteristic signs of ASD. However, there is currently limited clinical evidence supporting the use of vitamin B6-magnesium supplements in children with ASD.
Fortunately, there is some pending research in the works. In one pending clinical trial, children with a recent ASD diagnosis will be randomly assigned to receive a high dose vitamin B6-magnesium supplement or a placebo for three months.4 ASD would be assessed using the Autism Diagnostic Checklist before and after the intervention. Neurotransmitter production will also be assessed by measuring homovanillic acid4. The purpose of the study is to determine if high doses of vitamin B6 and magnesium can actually improve behavioral signs and symptoms associated with ASD, like they’ve been hypothesized to.
Vitamin B6 and magnesium for Attention-Deficit/Hyperactivity Disorder (ADHD)
In several studies, vitamin B6 and magnesium have been shown to reduce some of the symptoms of ADHD. Symptoms of hyperexcitability such as physical aggression, attention at school, anxiety, and hypermobility seem to be the most significantly impacted.5 Interestingly, when the vitamin B6-magnesium supplement was stopped, the clinical symptoms of ADHD that had subsided reappeared within a few weeks.
Furthermore, children with ADHD tend to have a greater risk of vitamin B6 and magnesium deficiencies which may contribute to ADHD symptoms. Without adequate vitamin B6, the brain cannot make enough neurotransmitters like dopamine, norepinephrine, serotonin, and GABA. All of these neurotransmitters affect how brain cells communicate and impact mood regulation and behavior.6 Vitamin B6 works synergistically with magnesium, and studies have shown that magnesium improves focus, anxiety, and sleep. In short, children with ADHD tend to have low levels of both vitamin B6 and magnesium which may contribute to their symptoms. Correcting these deficiencies may help improve mood regulation and behavior.
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Vitamin B6 for Anxiety and Depression
Due to the effects on brain neurotransmitters discussed throughout this article, vitamin B6 may also be an effective tool for managing the symptoms of anxiety and depression. Appropriate neurotransmitter synthesis is essential for mood regulation, and it is clear that vitamin B6 plays an integral role in these processes. In one study, high dose vitamin B6 supplementation reduced self-reported anxiety and reduced depression by increasing the influence of the neurotransmitter GABA.7
Vitamin B6 and Cognitive function
Considering the association between vitamin B6, mood, and mental function previously discussed, it’s easy to see how a connection may be drawn to improving overall cognitive function. Vitamin B6 also impacts the brain by managing homocysteine levels. A deficiency in vitamin B6 can result in elevations of homocysteine, a known risk factor for cerebrovascular disease that may have toxic effects on the neurons of the central nervous system8.
Considering the relationship between vitamin B6 and the brain, some studies have examined the effect vitamin B6 supplementation has on cognition. Most of the studies have been conducted on older adults and the results are inconclusive8. Little research on vitamin B6 supplementation has been done on children, but due to its vast roles throughout the body, particularly the brain, prioritizing vitamin B6 rich foods is a good way to ensure healthy growth and development in young children.
Supplementing vitamin B6:
There are several forms of vitamin B6 available for supplementation, including pyridoxine hydrochloride, pyridoxal-5-phosphate (P5P), and pyridoxine alpha-ketoglutarate (PAK).
Pyridoxine hydrochloride is the most common form of vitamin B6 found in supplements and is the form of vitamin B6 used in most research studies. It is considered safe and effective when taken at recommended doses.
Pyridoxal-5-phosphate (P5P) is the active form of vitamin B6 and is already in its metabolically active form, thus it doesn’t require any further conversion by the body, it may be more effective than pyridoxine hydrochloride for some people with certain genetic variations or other metabolic factors that affect the body’s ability to convert pyridoxine to P5P.
Pyridoxine alpha-ketoglutarate (PAK) is a form of vitamin B6 that is bound to alpha-ketoglutarate, which is a molecule involved in energy production. It may enhance the absorption and effectiveness of vitamin B6.
It’s worth noting that more research is needed to determine the optimal form of vitamin B6 for supplementation, and the best form may vary depending on the individual’s needs. It’s always a good idea to consult a healthcare professional before starting any supplement regimen.
It is important to note that antiepileptic medications deplete vitamin B6, while nonsteroidal anti-inflammatory drugs, oral contraceptives, and anti-parkinson’s drugs interfere with its metabolism. People taking these medications should supplement appropriately to avoid dangerous depletions. Supplemental doses should be determined by the individual’s primary care provider or a qualified nutrition
In conclusion, vitamin B6 is an important nutrient with a role in energy production, nutrient metabolism, neurotransmitter synthesis, and more than 100 enzymatic reactions. It can be found in both animal and plant foods such as poultry, chickpeas, potatoes, bananas, and fortified grains. A deficiency is quite rare, but may occur in the presence of numerous nutrient deficiencies or malabsorptive diseases. Toxicity is also rare, but can occur with prolonged supplementation. Toxicity can lead to sensory neuropathy and thus supplementation should be considered under the supervision of a qualified medical provider. Vitamin B6 supplementation is essential for children taking anti-epileptic medication and may be beneficial in easing PMS symptoms, Autism Spectrum Disorder, ADHD, anxiety and depression. There is mixed evidence supporting its overall efficacy at improving cognition, but while further studies are conducted, consuming plenty of vitamin B6 rich foods is the best way to support a healthy brain and body!
- National Institutes of Health. Vitamin B6. NIH. 2022.
- Kashanian M, Mazinani R, Jalalmanesh S, Babayanzad Ahari S. Pyridoxine (vitamin B6) therapy for premenstrual syndrome [published correction appears in Int J Gynaecol Obstet. 2020 Jul;150(1):135]. Int J Gynaecol Obstet. 2007;96(1):43-44. doi:10.1016/j.ijgo.2006.09.014
- Nye C, Brice A. Combined vitamin B6-magnesium treatment in autism spectrum disorder. Cochrane Database Syst Rev. 2005;2005(4):CD003497. Published 2005 Oct 19. doi:10.1002/14651858.CD003497.pub2
- Ershad F. The Neurobehavioral and Biochemical Effects of High Does of Vitamin B6 with Magnesium in Children with Autism spectrum Disorder: A Randomized, Double-Blind, Placebo Controlled Study. Clinical Trials.gov. 2022.
- M Mousain-Bosc, M Roche, A Polge, D Pradal-Prat, J Rapin, JP Bali . Improvement of neurobehavioral disorders in children supplemented with magnesium-vitamin B6. Magnesium Research. 2006;19(1):46-52.
- Greenblatt J. Nutritional Deficiencies: An Overlooked Cause of ADHD. 2017.
- Field D, Cracknell R, Eastwood J, Scarfe P, Williams C, Zheng Y, Tavassoli T. High-dose Vitamin B6 supplementation reduces anxiety and strengthens visual surround suppression. Human Psychopharmacology: Clinical and Experimental. 2022.
- Malouf R, Grimley Evans J. The effect of vitamin B6 on cognition. Cochrane Database Syst Rev. 2003;(4):CD004393. doi:10.1002/14651858.CD004393