‘I couldn’t walk’: GP’s personal story of vitamin B6 toxicity

Michelle Wisbey

10/04/2024 3:57:11 PM

Found in listed medicines, energy drinks, cereals and weight loss shakes, some people are consuming more than 50x the recommended daily intake.

Women's hand holding four tablets.
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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Dr Nerida Lee McDonald   11/04/2024 6:06:05 AM

I just can’t help thinking that we only have a small part of the story here. Although magnesium supplementation is mentioned, the author does not describe the dose of vitamin B6 that the doctor patient was taking. Additionally, vitamin B6 toxicity is known to cause peripheral neuropathy as does vitamin B6 deficiency. However the author describes proximal myopathy in the article with weakness and wasting of gluteal and quadriceps muscles and being unable to walk up a set of steps. I sincerely hope that this Doctor patient has her own GP and has been fully worked up by a neurologist to get to the real cause of her symptoms, and I wish her all the very, very best for her health.

A.Prof Vicki Kotsirilos, AM   11/04/2024 7:14:11 AM

This is very sad, to hear! It’s not the Magnesium tablets that caused the problem, it’s the Vitamin B6 (pyridoxine) ingredient found in the Magnesium supplement - that is the cause of the peripheral neuropathy. Most times it’s reversible but in a small percentage it is not. I don’t understand why manufacturers are adding high doses of vitamin B6 into their products! It’s not necessary. I keep taking patients off products containing high B6.
I always suspect and test for B6 toxicity in patients who present with symptoms or signs of neuropathy. Most times they resolve. It’s also important to report the reaction to ADRAC.
Also I think the pharmacist who dispensed the product had a duty of care to warn the patient of early signs, and probably more importantly not prescribe a magnesium product containing B6. Magnesium supplement alone would have sufficed. Thank you for sharing and raising awareness of this important issue.

Dr Dominic Francis Barnes   11/04/2024 7:24:48 AM

It was not clear from the article whether the OTC products listed vitamin B6 amongst their ingredients or were silent to its addition.

Dr Ruth Sophie Ratner   11/04/2024 7:39:54 AM

Another little known fact is that B6 can interfere with Parkinson's medications. My patient was adding complementary medicines, with hidden B6 because her Parkinsons symptoms were getting worse and her neurologist wanted to add more, but stopping the B6 immediately improved those. The toxicity symptoms, although abating, lasted (and 2 years later are still lasting) longer as, although the B6 leaves the blood fairly quickly it remains in the cells. Dietary B6 then compounds the problem so one has to watch that as well.

Dr Shyamala Hiriyanna   11/04/2024 3:54:30 PM

Yes I am having similar experience. I was advised to take magnesium by my endocrinologist. I did not realise that it had Vitamin B6 i am vegetarian. My Fe levels are low. I take Fab complex with vitamin and zinc. My symptoms started about 3 months ago. My fingers of both hands feel gritty and some what numb Finding it hard to get dressed and having difficulty with fine motor skills. I am also having difficulty holding things.suddenly lose grip. Some numbness in the feet and cant walk fast . Not steady on my feet. I am attending a neurologist and having investigation. i just cant understand how most supplements have vitamin B 6 Lots of people take vitamin supplements Lots of vegetarians and vegans.
I cant understand if TGA has a part to play so that this does not happen to anyone else.

Dr Alan James Fahey   11/04/2024 11:45:14 PM

I conduct medical education about mental health, exercise and nutritional supplements. I present what has been termed 'reversible pyridoxine polyneuropathy', and as said, it is not always reversible. The regulation in Australia years ago was 100 mg maximal dose per day. About 15 years ago it was noted that one woman overseas had developed problems whilst taking 27 mg and that countries varied with maximal recommended quantities. I have seen pain etc at 10 to 60 mg B3/day even after a decade and halve +/- stop the dose of magnesium/manganese/pyridoxine tablet plus give extra fluids resulting in symptoms going within weeks. ALA can help.
This is the tip of the iceberg. What is written in literature is only part of the story. When we spend time with patients we find out what really happens taking any products. I keep 'activity schedules' for all agreed tasks including prescribed medications plus exercise and relaxation for every patient. Only start or stop or stop one task at a time.

Dr NM   12/04/2024 7:21:21 PM

Wow this is very interesting and I am certainly going to change my practice. I have recommended Vitamin B6 (usually comes from pharmacy in 100mg - Natures own, Blackmore's) daily as a treatment for mastalgia (either cyclical or not as per my 2014 ed of Murtagh) and PMMD (as per Jean Hailes website and I checked today and still recommend 100mg). Works so well for both conditions but I am certainly going to check those patients I have recommended it too and advise. I never thought to check those doses as both are reliable sources.

Dr Susan Margaret McDonald   13/04/2024 3:53:16 PM

I am a retired GP and have taken pyridoxine 50-100mg daily prn for depression for some years. Fortunately not regularly. I bought a bottle a few months ago OTC that was 200mg. I was a bit puzzled as I had only ever been able to get 50mg or 100mg. I also took magnesium sporadically for cramps but last time I bought a magnesium and CoQ powder. Unbeknown to me it contains 50mg of pyridone!
I then developed a sensory neuropathy with tingling in my hands, feelings of cold water running down my calves occasionally and numbness on the soles of my feet like wet blotting paper. The symptoms are not disabling.
Until reading this article I had no idea toxicity could occur at what I thought were low doses. I have now stopped all B6 and checked the supplements I have to see there is no B6 in them. Unfortunately most contain lots of other unnecessary additives.
I had many patients when I was practising who had idiopathic sensory neuropathies.
If only I had known to check their B6 levels.

Dr Susan Margaret McDonald   13/04/2024 3:58:45 PM

Most of these products are OTC and sold in pharmacy supermarkets without a pharmacist being involved. The additive writing is so small the average older person can't read it without a magnifying glass!

Dr Andrew S. Beavon   7/05/2024 10:24:14 AM

Typical story and unfortunately so common.Mg supplements often contain B6 and unless specific supplement is reviewed easy to miss on history alone.
Even if diabetic neuropathy is suspected please check B6 .Recently seen patient post weight loss surgery on supps with neuropathy a renal dialysis patient similarly etc etc .