Too much b6 symptoms
Pro Research Analysisby 
Searched over 200M research papers
Symptoms of Excessive Vitamin B6 Intake
Introduction to Vitamin B6 and Its Importance
Vitamin B6, also known as pyridoxine, is a water-soluble vitamin essential for various metabolic processes, including amino acid, carbohydrate, and lipid metabolism. It is naturally present in many foods and is also available in dietary supplements. However, both deficiency and excessive intake of vitamin B6 can lead to health issues2 6.
Peripheral Neuropathy and High B6 Intake
One of the most well-documented adverse effects of excessive vitamin B6 intake is peripheral neuropathy. This condition is characterized by sensory neuropathy of the axonal type, which predominantly affects the extremities. Symptoms include paraesthesia, hyperaesthesia, bone pains, muscle weakness, numbness, and fasciculation2 3 5. Studies have shown that these symptoms often improve upon discontinuation of vitamin B6 supplements2 3.
Neurotoxicity and Cellular Effects
Research indicates that high doses of pyridoxine can induce neurotoxicity. This is primarily due to pyridoxine's ability to inhibit the active form of vitamin B6, pyridoxal-5'-phosphate, leading to symptoms similar to those of vitamin B6 deficiency. Cellular studies have demonstrated that pyridoxine can cause cell death and increase the expression of pro-apoptotic markers such as Bax and caspase-86.
Recommended Upper Intake Levels
The European Food Safety Authority (EFSA) has established a tolerable upper intake level (UL) for vitamin B6 to prevent toxicity. For adults, the UL is set at 12 mg/day, with lower levels recommended for children based on age. This recommendation is based on the relationship between high vitamin B6 intake and the development of peripheral neuropathy7.
Case Studies and Clinical Observations
Several case studies have highlighted the neurotoxic effects of vitamin B6 at doses lower than previously thought to be harmful. For instance, a study involving 172 women found that those with neurological symptoms had been taking an average of 117 mg of B6 daily, and symptoms resolved upon discontinuation of the supplement3. Another case report described excessive bleeding in a pediatric patient due to pyridoxal-5-phosphate supplementation, expanding the spectrum of known vitamin B6 toxicity10.
Conclusion
While vitamin B6 is essential for health, excessive intake can lead to serious adverse effects, particularly peripheral neuropathy and neurotoxicity. It is crucial to adhere to recommended intake levels to avoid these potential health risks. Further research is needed to fully understand the mechanisms of B6 toxicity and to refine guidelines for safe supplementation.
Sources and full results
Most relevant research papers on this topic
The Effects of Vitamin B6 Supplementation on premenstrual Symptoms
Vitamin B6 supplementation may improve premenstrual symptoms related to autonomic reactions and behavioral changes, but caution is advised due to potential toxic effects of low doses.
RCTThe Role of Vitamin B6 in Peripheral Neuropathy: A Systematic Review
High vitamin B6 levels may cause neurotoxic peripheral neuropathy, while low B6 levels may be a potential risk factor for peripheral neuropathy, but further studies are needed.
Systematic ReviewCharacteristics of pyridoxine overdose neuropathy syndrome
Pyridoxine overdose can cause neurotoxic symptoms, with complete recovery possible within 6 months of stopping the medication.
Observational Study
Highly CitedTreatment of Infantile Spasms with High‐Dosage Vitamin B6
High-dose vitamin B6 effectively treats infantile spasms in 5 out of 17 cases, with no serious adverse reactions and no relapse observed.
Highly CitedVitamin B6 levels do not correlate with severity of neuropathy in chronic idiopathic axonal polyneuropathy
Moderately elevated vitamin B6 levels, even in the 100 to 200 g/L range, are not associated with significantly worse neuropathy signs or symptoms in chronic idiopathic axonal polyneuropathy patients.
Observational StudyThe vitamin B6 paradox: Supplementation with high concentrations of pyridoxine leads to decreased vitamin B6 function.
High doses of vitamin B6 supplements can cause neuropathy due to pyridoxine, which inhibits the active form of pyridoxal-5'-phosphate, leading to symptoms similar to vitamin B6 deficiency.
In Vitro StudyHighly CitedScientific opinion on the tolerable upper intake level for vitamin B6
The EFSA Panel on Nutrition, Novel Foods, and Food Allergens has established a tolerable upper intake level of 12 mg/day for vitamin B6 for adults, based on a reference point of 50 mg/day and animal studies.
Literature ReviewSafety and Efficacy of High-Dose Vitamin B6 as an Adjunctive Treatment for Antipsychotic-Induced Hyperprolactinemia in Male Patients With Treatment-Resistant Schizophrenia
High-dose vitamin B6 (vB6) is a safe and effective adjunct treatment for antipsychotic-induced hyperprolactinemia in male patients with treatment-resistant schizophrenia, showing better attenuation of AIHP and lower adverse secondary effects.
RCTEffect of vitamin B6 on the side effects of a low-dose combined oral contraceptive.
Vitamin B6 may reduce the severity of oral contraceptive side effects, but its effectiveness is more likely due to a placebo effect than a marginal pharmacological effect.
RCTB6 and Bleeding: A Case Report of a Novel Vitamin Toxicity
Vitamin B6 therapy can exacerbate bleeding symptoms in patients with pyridox(am)ine-5-phosphate oxidase deficiency and mild hemophilia A, highlighting the need for vigilance in monitoring bleeding symptoms.
Case Report