By Rachel McDonald, the Australian Science Media Centre
The Therapeutic Goods Administration (TGA) this week finalised plans to tighten up restrictions on supplements and products containing high doses of vitamin B6 - from pyridoxine, pyridoxal or pyridoxamine - amid nerve damage risks.
From June 2027, supplements containing a recommended daily dose between 50-200 milligrams of vitamin B6 will be moved behind the counter at pharmacies and will require the advice of a pharmacist before purchase. Any product with a daily dose of more than 200mg already requires a prescription.
Vitamin B6 intake is essential for human health, and Dr Ian Musgrave from the University of Adelaide told the AusSMC it played various important roles in the human body.
"The body uses vitamin B6 in many ways, including amino acid metabolism, glucose metabolism, lipid metabolism, and haemoglobin synthesis. It is important for normal brain development," Dr Musgrave said.
University of South Australia Senior Lecturer in Pharmacy Vijay Suppiah said most people can meet their B6 needs through food.
"Salmon, chicken, potatoes, and chickpeas are excellent sources. Toxicity from food is extremely rare," Dr Suppiah said.
"The recommended dietary intake for a healthy adult is 1.3-1.7 mg/day. Vitamin B6 deficiency is more likely to occur in the elderly, or those with alcohol dependence, obesity, or certain kidney, liver and autoimmune conditions. However, vitamin B6 deficiency is uncommon among the Australian population."
Dr Musgrave said there can be a misconception that because something is essential, it is also safe. However, B6 is one of many vitamins that can cause harm at high concentrations.
"Too much vitamin B6 can cause a number of adverse effects, with a condition called peripheral neuropathy being of major concern. Peripheral neuropathy can involve numbness and tingling, difficulty in walking, pain and loss of coordination," he said.
He said the European Food Safety Authority recommended an upper limit of 12 mg/day for adults, with toxicity generally occurring as a result of long-term supplement use.
Dr Peter Crack, Head of the Neuropharmacology Laboratory at the University of Melbourne, said B6–induced neuropathy was uncommon but rising due to the popularity of supplements.
"Neuropathy is almost never seen with dietary intake alone, and occurs almost exclusively in people taking supplements at doses well above physiological needs," he said.
Dr Crack said most reported cases involved chronic intake above 100-200mg a day and ocurred in 1–4% of people chronically exposed to excessive levels.
"Even moderate but sustained intakes (e.g., 50 mg/day over months to years) have been linked to sensory neuropathy in susceptible individuals."
Chemistry Professor Oliver Jones from RMIT University said people who take various supplements may be unaware of how much B6 they are taking.
"The problem is that vitamin B6 is in a range of products, so it is easy to accidentally take too much without realising. People may then not link their symptoms to the supplements, so they can be ill for some time and not know why," Prof Jones said.
"The issue of vitamin B6 toxicity illustrates an important point - you can have too much of a good thing; everything is toxic in the right amount. Just because a certain amount of a substance might be good for us does not mean that larger amounts are better. The dose makes the benefit as well as the poison."
Geraldine Moses, Adjunct Associate Professor at the University of Queensland, said the TGA's changes were a "great relief".
"After all, the toxicity of vitamin B6 has been known for over 30 years, so it is about time the TGA took steps to protect the public," A/Prof Moses said.
"This decision has been a long time coming, as the UK has regulated Vitamin B6 in doses > 50mg as a prescription drug since 1997. In the meantime, thousands of Australians have unwittingly consumed high doses of B6, either from individual products or multiple products with doses that accumulate to an overdose, and doctors were largely unaware that B6 could even BE toxic.
"Thankfully, doctors are now more aware; they know what the vitamin B6 toxidrome looks like and can diagnose it more quickly and accurately."
She said it was a shame the ruling wouldn't come into effect until mid-2027. In their announcement, the TGA said the deadline was chosen to give industry, healthcare practitioners and businesses time to make the necessary changes.
In the meantime, Dr Suppiah said the safest supplement strategy for consumers was to focus on food sources where possible and keep doses low.
"If you choose supplements, stick to low-dose options like multivitamins or B-complex products that provide less than 10mg per day. Always check labels and consult a healthcare professional before starting any high-dose regimen," he said.
"For patient usage duration of longer than six months, and over 50 mg/day vitamin B6, regular monitoring by healthcare professionals is recommended."
You can read the full Expert Reaction here
This article originally appeared in Science Deadline, a weekly newsletter from the AusSMC. You are free to republish this story, in full, with appropriate credit.
Contact: Rachel McDonald
Phone: +61 8 7120 8666
Email: info@smc.org.au