Never take supplements without checking this key detail, they could be toxic

These 7 supplements can be toxic for your body, here’s how to take them safely.

Popular supplements can be toxic
© Mariana Rascão / UNSPLASH
Popular supplements can be toxic

In this day and age, many of us are more health-aware than we’ve ever been before. This can certainly take an unhealthy, obsessive turn, especially with the rise of social media and ever-present advertising.

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However, for the most part it is a good thing: we want to look after ourselves. This usually involves getting some exercise, eating a balanced diet, and making sure your body is properly hydrated. However, it can be tricky to get everything you need from your diet, especially if you have any medical requirements or ethics that dictate what you eat.

A lot of us therefore look for a quick fix in the form of supplements. The average person will surely have a rogue bottle of zinc kicking about in their medicine cabinet, or a tub of vitamins on their bedside table. There’s nothing wrong with boosting a healthy lifestyle with products like these, and they can help to keep you robust when the cold weather comes knocking, but there are risks involved.

Here are 7 popular supplements that can cause toxicity, which can lead to a simple headache or - in the worst case scenario - death.

Toxicity of supplements

Supplements can be split into two groups, and the different types hold different risks. Most are water-soluble, meaning they are digested and do not stay in your system for very long. Any excess is excreted through your urine. However, some essential vitamins - namely A, D, E and K - are fat-soluble. They are stored in body tissues and therefore taking large doses of them is more likely to lead to toxicity. It is worth noting that, although less likely, large doses of water-soluble vitamins and minerals can also lead to hypervitaminosis (the medical term for vitamin toxicity).

Tolerable Upper Intake Level

The Food and Nutrition Board of the National Academies of Sciences, Engineering and Medicine has set a Tolerable Upper Intake Level, or UL, to help determine how much of a supplement a person can reasonably take without running any major risks.

Although in the worst case scenario, people can die from exceeding this limit, the side effects will depend on the supplement type, dosage, duration and consumer.

Vitamin A

Vitamin A is a fat-soluble supplement key for healthy vision, a strong immune system, growth and reproduction. Taking too much of this supplement can cause ‘headache, blurred vision, nausea, dizziness, muscle aches and problems with coordination’, according to EatingWell. In severe cases it could lead to a coma or death, and if taken when pregnant, could be responsible for birth defects.

Vitamin D

Vitamin D is also good for the immune system, as well as building and maintaining strong bones and teeth. With the dentist crisis that’s happening in the UK right now, this one is important. However, the supplement has been linked to ‘heart disease, diabetes, certain cancers, autoimmune diseases and neurological disorders’, according to an article published in Aging and Disease.

Vitamin E

This one is essential for immune, cellular and vascular health. This antioxidant is often consumed by those with gastrointestinal disorders that inhibit fat absorption, but taken in excess it can ‘increase the risk of bleeding by reducing the blood's ability to clot, which can increase the risk of hemorrhage’.

Vitamin K

You are less likely to need Vitamin K, as it is easily found through your diet - say hello to leafy greens - but some people still take it. This fat-soluble is not as risky as the others, and there's limited evidence of it causing toxicity. However, people who take blood thinners should avoid taking this supplement, and it can trigger allergic reactions and potential liver damage.

Vitamin B6

This supplement plays a part in many enzymatic functions, including protein synthesis, immune function and cognitive function. It is water-soluble, but when taken in excess over a long period, it can cause nausea, heartburn, and an increased sensitivity to the sun.


This mineral is a very commonly taken supplement, often by menstruating women because it is a vital component of hemoglobin - a red protein responsible for transporting oxygen in the blood. It also plays a role in muscle metabolism and physical and neurological growth. According to EatingWell:

And high-dose supplementation can increase the risk of constipation, nausea, abdominal pain, diarrhea and vomiting.

You should also be aware that iron reduces zinc absorption in the body.


Zinc is an antioxidant and has a key role in immunity and wound-healing. The recommended daily intake is 8 mg a day for women over 19, and 11 mg a day for men. The UL is 40 mg a day for most people, and taking more than 100mg can cause headaches, fever, and an increased risk of prostate cancer.

How to take supplements safely

Always read the instructions on these products, and don’t be too gung-ho in your approach. You should also check that all your bottles and tubs are still within their best-before limit. Consult a pharmacist or doctor if you are unsure about any of the risks involved and never take more than the recommended dose for your age and gender.

Read more:

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Sources used:

EatingWell: These 7 Supplements Can Be Toxic If You Take Too Much

National Library of Medicine: Vitamin D and Chronic Diseases

Taking dietary supplements with this common drug could be dangerous to your health Taking dietary supplements with this common drug could be dangerous to your health