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‘I couldn’t walk’: GP’s personal story of vitamin B6 toxicity
Found in listed medicines, energy drinks, cereals and weight loss shakes, some people are consuming more than 50x the recommended daily intake.
There are more than 1000 listed medicines in Australia which contain vitamin B6.
When Dr Mary Buchanan started taking a daily dose of magnesium four years ago, it offered the pain relief she had long been searching for.
Living with genetic restless leg syndrome, the GP’s cramps and paraesthesia had been worsening for years, eventually becoming so severe it was keeping her up at night.
Her pharmacist recommended a magnesium tablet and when the cramps eased, she thought a road to recovery was finally in sight.
But little did Dr Buchanan know, this was the beginning of a long and painful journey which would ultimately result in a vitamin B6 toxicity diagnosis.
‘I noticed a slight reduction of strength in upper leg muscles and in my glutes, then there was a continuous slow deterioration of muscle strength,’ she told newsGP.
‘Then, I couldn’t walk – I was getting to where about 100 metres was a struggle.
‘I used to go to the tennis and the footy, but I haven’t done that for the last year now because walking a distance and going up and down stairs is just impossible.’
The mystery illness eventually became so bad Dr Buchanan sought help, consulting a neurologist and embarking on a radiology and pathology screening regime.
After an anxious wait, she received her vitamin B6 toxicity and peripheral neuropathy diagnosis, caused by the magnesium tablets she had now been taking for several years.
‘It was confirmed that I had muscle weakness in both legs, in my glutes, but there are no treatments, there’s nothing else you can do but stop the tablets and wait and see,’ Dr Buchanan said.
‘I’m disappointed it’s not improving anywhere near as much as I would like – it’s very slow, there are continual delays down the back of my legs and a really stiff feeling.’
Now, Dr Buchanan is hoping to raise awareness among fellow GPs regarding the potential dangers of vitamin B6 toxicity.
More than 1000 listed medicines in Australia currently contain vitamin B6, which can also be found in products such as energy drinks, breakfast cereals, or weight loss shakes.
The Recommended Dietary Allowance of vitamin B6 varies depending on age and gender, ranging from 1 mg/day for children aged 9–13 years, to 1.7 mg/day for men older than 50 years.
In 2022, after discovering a ‘lack of awareness’ about the vitamin, the Therapeutic Goods Administration (TGA) strengthened labelling requirements so products containing daily doses over 10 mg must carry a warning about peripheral neuropathy.
‘A review of the patient’s vitamin B6 intake is recommended, paying close attention to potential sources such as multivitamins and magnesium and zinc products, particularly when taken in combination,’ the TGA said.
Dr Terri-Lynne South, a GP and dietitian, said most patients are unaware they are consuming the vitamin at all, let alone at levels sometimes 50 times more than the recommended daily limit.
‘It’s not something that GPs would typically know about, and the symptoms can make it tricky to diagnose – tingling and numbness in the hands and the feet would be the most common, but they can be quite nonspecific,’ she told newsGP.
‘The good news is it’s reversible, but it is sneaking into the average Australian’s consumption in multiple ways.
‘There needs to be much greater awareness because it’s hard to know the true prevalence of this problem.’
Up to August 2022, the TGA received 32 adverse event reports establishing a possible causal association between peripheral neuropathy and products containing vitamin B6.
Two thirds of those involved daily doses of 50 mg or less, and 28% involved multiple medicines containing vitamin B6, some of which did not have a warning label.
Clinical dietitian Dr Cathy Harbury has been spearheading an awareness campaign about the toxicity, saying most people are already receiving an adequate dose of the vitamin through their diet without any need to supplement it.
‘There are absolutely thousands of multivitamins that are on the supermarket and chemist shelves with B6 levels which are above the recommended dietary intake,’ she told newsGP.
‘There’s a lot that have anywhere between 10, 20, or 50 milligrams of B6, well over the recommended daily intake.
‘We need to inform the general population because you can buy these on the supermarket shelves, and they would have no clue of the B6 levels.’
Dr Harbury added that for GPs, a few simple questions about a patient’s use of multivitamins or supplements is a simple way to detect the toxicity.
The warning comes as Australians’ consumption of these over-the-counter medicines, energy drinks, and protein shakes continues to escalate.
Around 43% of Australians report taking vitamins and supplements and another 26% have taken digestive system medications.
Meanwhile, more than half of children report having tried an energy drink, 19% consume them weekly, and 2% drink them every day.
Dr South is now urging GPs to remind their patients that over-the-counter products are not necessarily guaranteed to be safe and without concern.
‘People really do need to know what they’re putting into their bodies, especially if it is some sort of tablet, but no matter what it is,’ she said.
‘GPs must be aware of vitamin B6 toxicity and consider testing, but even before testing there’s a great opportunity to ask our patients about their over-the-counter supplements and energy drinks.
‘We should routinely ask about supplements, medications, and complementary medications, but often we don’t because we’re time poor and when patients tell us they’re on these sorts of things, a lot of the times we don’t really know what to do with that.’
It has been a year since Dr Buchanan stopped taking magnesium tablets, but with her recovery still ongoing she fears the impacts will be lifelong.
She is speaking out with the hope that no one else will have an experience like hers.
‘I’m still nowhere near back to normal and I think it’s probably there to stay,’ Dr Buchanan said.
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