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Health dangers of vitamin supplements

While many believe that vitamin supplements are a simple way to boost and improve our overall health, there are hidden health dangers to be aware of. Recent cases of vitamin b6 toxicity from supplements sold in Australia are a prime example of this.

In this month’s blog, we take a closer look at vitamin supplements and how they may not always deliver the best outcomes for our health.

What are vitamin supplements?

Vitamin, or dietary, supplements are products designed to provide nutrients that may be missing from your normal diet.

They contain concentrated vitamins, minerals or nutrients and normally come in tablet, capsule, powder, or liquid form. Common examples include vitamin C, iron, and calcium tablets, fish oil capsules, turmeric powder, and raspberry leaf tea.

Many vitamin supplements do not require a prescription and can be easily bought over the counter at pharmacies and supermarkets.

Why and when are supplements used?

Most of the vitamins and minerals our bodies require come from eating a normal balanced and varied diet. However, some people may be advised to take a supplement to help counter specific vitamin or mineral deficiencies.

For example, people who:

  • are pregnant or breastfeeding;
  • are diagnosed with malnutrition and aren’t getting enough nutrition from the food they are eating;
  • have a health condition that prevents their body from absorbing the nutrients it needs (for example, people with chronic kidney disease who are on dialysis);
  • are taking a medicine that affects certain dietary nutrients;
  • have a health condition that requires the need for a particular nutrient (e.g. people at risk of osteoporosis may need to take a calcium supplement);
  • have a restricted diets and aren’t getting enough nutrients through food (e.g. vegetarians and vegans); or
  • have a diagnosed nutritional deficiency (e.g. where a blood test shows you have a vitamin D deficiency).

What are the risks of vitamin supplements?

As with any type of medicine, vitamin supplements come with their own risks and dangers. They can have side effects or interact with other medicines, making them dangerous or less effective.

Getting too much of a particular vitamin or mineral can also lead to serious harm. When vitamins are taken as supplements, they are introduced into the body at levels that are higher than what you could obtain through your normal diet.

Some people also mistakenly believe that taking larger amounts of vitamins is better for you. However, taking more than the recommended doses can result in potential health problems. For example:

  • Vitamins A, B6, D, E and K – can be toxic when taken in high doses.
  • Too much vitamin A or E when pregnant – can cause serious harm to your baby.
  • Folate – can hide vitamin B12 deficiencies.
  • High levels of vitamin B6 – has been linked to nerve damage.
  • Doses of vitamin C above one gram – can cause diarrhoea.
  • Large doses of vitamin C – can cause nausea, abdominal cramps, headaches, fatigue, kidney stones, and interfere with your body’s ability to process other nutrients.
  • Excessive amounts of vitamin C – can interfere with medical tests (such as diabetes), giving a false result.
  • High doses of vitamin A – may cause birth defects, as well as central nervous system, liver, bone and skin disorders.
  • High-dose vitamin E – has been linked to higher rates of early death.
  • Zinc, iron, chromium and selenium – can be raised to toxic levels in the body when taken at just 5 times the recommended dietary intake.
  • Large intakes of fluoride (especially in childhood) – may stain or weaken teeth.
  • Very large doses of fish oil – can lead to decreased blood clotting.
  • Iron – can cause gastrointestinal upset, nausea and black bowel actions. Severe toxicity can lead to coma and even death.
  • Curcumin and curcumin longa (turmeric) – may cause liver injury.

Many supplements also contain additional vitamins and minerals that some people may not be aware of, so it’s important to always read the label and ingredients list carefully to know exactly what you are taking and how much of it you are consuming.

A quick look at the Therapeutic Goods Administration (TGA) safety alerts page shows a range of health concerns to be aware of for a number of vitamin and mineral supplement products available in the Australian market.

Vitamin B6 toxicity

One of the more recent cases of serious health harms caused by vitamin toxicity in Australia has been with Vitamin B6 and its link to peripheral neuropathy.

Peripheral neuropathy is caused by damaged to your peripheral nerves – that is, your sensory, motor, and automatic nerves.

Symptoms usually occur in the hands and feet and include:

  • tingling, pins and needles or electric type pains;
  • numbness;
  • areas that feel ‘hot’ or have a burning sensation;
  • cold areas which are difficult to warm up;
  • the sensation of insects crawling on your skin; and
  • muscle weakness, cramps or aching.

After receiving numerous reports of peripheral neuropathy in recent years, which indicated a possible link with products containing vitamin B6, the TGA undertook a review and found that:

  • Peripheral neuropathy can occur at doses of vitamin B6 less than 50 mg.
  • Peripheral neuropathy can occur when people are taking multiple products containing vitamin B6.
  • The risk appears to vary between people – no minimum dose, length of use or underlying risk factors were identified.

In many cases, people reported they weren’t aware they had even consumed vitamin B6, as they were taking a magnesium supplement. Others reported taking multiple products that each contained a low dose of vitamin B6, not realising the potential cumulative effect.

As a result of their review, the TGA has updated regulations, so that:

  • Products containing a daily dose of vitamin B6 above 10 mg now require a warning about peripheral neuropathy.
  • The maximum permitted daily dose of vitamin B6 in individual products has been reduced from 200 mg to 100 mg for adults, with lower daily dose limits for children, depending on their age.
  • From June 2027, customers will require a pharmacist’s supervision to purchase products containing more than 50mg of vitamin B6, and anything with more than 200mg will need a prescription.

How to safely take vitamin supplements

The best option for taking vitamins safely is to seek professional advice from your doctor to determine what, if any, supplements you may require for your particular health circumstances and how these may interact with any existing prescription medicines and medical treatments you are undertaking.

If you do need to take vitamin supplements, make sure you are taking them at the recommended dosage level and assess the potential benefits and risks. It’s also important to examine all ingredients listed on the product, so you can identify the exactly what you are taking, the dose being taken, and the potential for cumulative overdose from repeated ingredients in multiple products.

Vitamin and mineral supplements should only be used as a short-term measure. If you are taking supplements because you feel you may be lacking in certain vitamins and minerals, it may be better to look at changing your diet and lifestyle instead. Your doctor or a dietitian can help advise you on this.

If you do have any side effects or problems after taking dietary supplements, stop taking them immediately, report them to the TGA, and see your doctor.

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