For many health-conscious people, supplements feel like the final tick on the wellness checklist but nutrition doesn’t always reward enthusiasm. Photo / Getty Images
When I was diagnosed with peripheral neuropathy, blood tests revealed I had extremely high vitamin B6 levels. That surprised me, as I had been taking only a 100mg B6 supplement daily, suggested for premenstrual problems. I can’t remember what the symptoms were now, as I’m 78. My
doctor commented on the very small print often used for dosage warnings on dietary supplements.
Answer:
For many health-conscious people, supplements feel like the final tick on the wellness checklist: whole foods, regular movement, good sleep – plus a vitamin or two for reassurance. But nutrition doesn’t always reward enthusiasm. Piling supplements on top of an already balanced diet can introduce risks most people never see coming, including side effects that seem wildly out of proportion to something sold in the health aisle. Case in point: your experience of developing peripheral neuropathy after taking a vitamin B6 supplement.
Peripheral neuropathy is a known serious side effect of vitamin B6 supplements. It is characterised by tingling, burning or numbness, usually in the hands or feet. Delayed diagnosis and continued exposure can allow the condition to progress, whereas early detection and action can improve the chances of reversing symptoms and repairing nerve damage.
Your 100mg daily vitamin B6 supplement was far higher than the 1.3mg adults up to 50 years old need, or the slightly higher 1.7mg for older men and 1.5mg for older women. It also exceeds the 50mg upper limit, above which B6 can cause peripheral neuropathy. This is especially relevant given that vitamin B6 is abundant in everyday foods, with poultry, fish, organ meats, starchy vegetables such as potatoes and kūmara, non-citrus fruits, nuts, legumes and wholegrains all providing this essential nutrient. Your 100mg supplement came on top of the B6 you were already getting from your diet.
Still, as you’ve noted, vitamin B6 supplements are recommended in certain situations. Research has found it can help treat nausea and vomiting (morning sickness) in pregnancy and specific genetic types of anaemia, and may improve premenstrual syndrome symptoms such as anxiety, depression, moodiness, irritability, bloating and abdominal discomfort, according to a 2025 article in Nutrition Reviews.
But herein lies the conundrum, while women with PMS-related symptoms may benefit from vitamin B6 at 50mg/day or more, long-term consumption of high doses (over 100mg a day) has been linked to adverse side effects, including peripheral neuropathy. This means the potential for benefit must be weighed against the potential for harm, and appropriate dosage adhered to. Less is more when it comes to B6 – and indeed for many other supplements.
Appropriate supplementation can be a useful health tool, but it must be balanced with potential risks, which are typically noted on labels. Doctors are increasingly seeing side effects from supplement overuse in otherwise healthy, well-nourished people. Symptoms can include gastrointestinal issues such as nausea, bloating and reflux; neurological symptoms such as headaches, dizziness and fatigue and, in more serious cases, nerve damage, liver injury or kidney problems.
Vitamin B6 supplements are not the only ones that come with a warning. High doses of vitamins A and B3 can affect liver function, and substantial amounts of vitamin C or calcium can contribute to kidney stones. Supplements can also disrupt nutrient balance. For example, excessive zinc supplementation can lead to a copper deficiency or interfere with prescription medications. Driven by the assumption that if a nutrient is essential then more must be better, some consumers end up causing themselves more harm than good.
Regular consumers of supplements typically have higher dietary nutrient intakes than their peers, making supplementation unnecessary unless a particular health condition calls for it, as in your prior usage for PMS symptoms.
A varied, well-balanced diet reduces the risk of both inadequate and excessive nutrient intakes, being both more effective and less risky than haphazard supplement use. Whole foods provide both identified and unidentified protective substances at a fraction of the cost of supplements. So, before spending money on a dietary supplement, reassess your eating habits and, better still, seek advice from a registered nutritionist or dietitian.
Email your nutrition questions to listenerlife@aremedia.co.nz
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