B6 toxicity symptoms
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Symptoms of Vitamin B6 Toxicity
Vitamin B6, also known as pyridoxine, is essential for various metabolic processes in the body. However, excessive intake can lead to toxicity, manifesting in several adverse symptoms. This article synthesizes findings from multiple studies to provide a comprehensive overview of the symptoms associated with vitamin B6 toxicity.
Neurological Symptoms of Vitamin B6 Toxicity
Peripheral Neuropathy and Sensory Neuropathy
One of the most common and well-documented symptoms of vitamin B6 toxicity is peripheral neuropathy. This condition primarily affects the sensory nerves, leading to symptoms such as paraesthesia (tingling or prickling sensation), hyperaesthesia (increased sensitivity to stimuli), numbness, and muscle weakness, particularly in the extremities 269. These symptoms are often bilateral and can be severe enough to impair daily activities. In some cases, patients report bone pains and fasciculations (muscle twitching) .
Tonic Convulsions and Impaired Coordination
High doses of vitamin B6 can also lead to more severe neurological symptoms, such as tonic convulsions. Studies on animals have shown that doses above 1 gram per kilogram can cause convulsions, characterized by the hind limbs stretching away from the body and the forelimbs bending under the body 17. These convulsions can be fatal if the dose is high enough, leading to death within 36 to 72 hours .
Sensory Neuronal Pain
Recent studies have reported cases of sensory neuronal pain due to vitamin B6 supplementation. This pain is often described as a burning or tingling sensation and is thought to be caused by the inactive form of pyridoxine inhibiting the active form, pyridoxal-5'-phosphate, leading to symptoms similar to those of vitamin B6 deficiency .
Other Symptoms of Vitamin B6 Toxicity
Bleeding Disorders
A novel symptom of vitamin B6 toxicity is excessive bleeding. This was observed in a pediatric case where a patient with pyridox(am)ine-5-phosphate oxidase deficiency experienced exacerbated bleeding symptoms due to vitamin B6 therapy . This finding suggests that high levels of vitamin B6 can interfere with normal blood clotting mechanisms.
Neonatal Toxicity
In newborns, high maternal intake of vitamin B6 during pregnancy and breastfeeding can lead to neonatal toxicity. Symptoms in newborns include diffuse tremors, which typically resolve once the maternal supplement is discontinued .
Conclusion
Vitamin B6 toxicity can lead to a range of symptoms, primarily affecting the nervous system. Peripheral neuropathy, sensory neuronal pain, tonic convulsions, and impaired coordination are the most common neurological symptoms. Other symptoms include bleeding disorders and neonatal toxicity. It is crucial to monitor vitamin B6 intake, especially when using supplements, to avoid these adverse effects. If symptoms of toxicity appear, discontinuing the supplement usually leads to symptom improvement.
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