Research Grant - 2024

Watch Dr Matthew Silsby accept the research grant award and hear a bit about the project.

Project Summary:

Vitamin B6 is commonly found in supplements such as multivitamins, migraine products, nerve health products, and energy drinks. It is often present in amounts that exceed the recommended daily intake, leading to a buildup of B6 in the body. This can result in B6 toxicity, where high levels of the vitamin interfere with normal nerve function, particularly affecting sensory nerves. Symptoms may include tingling, numbness, burning pain, and in more severe cases poor balance. Because of its widespread inclusion in supplements, B6 toxicity is an increasingly common problem. 

Although B6 toxicity has been recognized for decades, exactly how B6 affects the nerves remains unclear. It is suspected that B6 disrupts the usual neurotransmitters responsible for preventing nerve overactivity. This nerve hyperexcitability could explain the types of sensory symptoms patients experience. The current treatment for B6 toxicity is to discontinue supplements while the body naturally eliminates the excess vitamin, a process that can take many months. During this time, managing symptoms can be challenging. 

Nerve hyperexcitability testing is an established technique that directly measures the excitability of nerves by applying small electric pulses to the wrist and ankle. Interestingly, this technique has not previously been used in those with B6 toxicity. This project will comprehensively assess nerve function, including nerve hyperexcitability testing, in patients with B6 toxicity, to assess the theory of over-excitation of nerves. If confirmed, this could lead to better targeted treatments aimed at stabilising overactive nerves, potentially improving symptom management while waiting for B6 to be eliminated naturally.

Outcomes:

In this project, Dr Silsby and his team assessed peripheral nerve function in patients with vitamin B6 toxicity and measured nerve excitability to uncover the underlying pathophysiology. Their hypothesis was that nerve excitability parameters will be abnormal in patients with Vitamin B6 toxicity.

They aimed to recruit 30 participants with sensory symptoms as well as elevated vitamin B6 levels (above 250 nmol/L, confirmed with a blood test). Participants were assessed at baseline, after which they stopped taking all B6-containing supplements, then were assessed again after 6 months to assess whether nerve function changed as B6 was eliminated.

During the Grant period there was significant media coverage about the risk of B6 toxicity. This was welcomed as it brought attention to the issue, however also stymied efforts to recruit participants as vitamin B6 use was curtailed in the community. Consequently, the study has so far recruited 10 of the planned 30 subjects, 5 of which returned for follow up assessments after 6 months.

The preliminary results found some neurophysiological differences compared to healthy controls. The routine nerve conduction studies were normal, but the axonal excitability studies pointed to increased hyperexcitability following depolarisation. Vitamin B6 levels normalised for all 5 patients who returned for review 6 months later; however, symptoms persisted for most and some excitability parameters remained abnormal.

Taken together, these findings could support the hypothesis that vitamin B6 causes hyperexcitability of sensory nerves before development of neuropathy, that the levels return to normal after cessation of supplementation, but that there is incomplete recovery in some cases. It should be stressed, however, that these results are preliminary and based on low numbers, requiring further analysis with a larger cohort before drawing specific conclusions.

Outcomes submitted July 2026.

Further Information:

If you would like to learn more about vitamin B6 toxicity, you can visit our overview article: What is Vitamin B6 Toxicity?

This article covers key information including symptoms, tips for checking supplement labels, a personal story from someone living with B6 toxicity, updates on supplement regulation in Australia, and more.