Six potential harms of dietary supplements

Products containing vitamins and minerals are used by 47% of Australians, often to supplement their diet rather than treat disease. In an article in the August edition of Australian Prescriber, Dr Geraldine Moses from the University of Queensland explains that there are many potential harms associated with using dietary supplements, of which consumers are generally unaware.

Sales of dietary supplements reached $5.6 billion in 2019 after having more than doubled over the preceding 10 years.

Vitamin and mineral supplements can be important to treat certain illnesses or nutritional deficiencies. For example, vitamin B₃ can be used for high cholesterol and folic acid can be used in pregnancy to prevent birth defects. When used for general wellness, however, their risks may outweigh their benefits.

“One reason for the persistent popularity of vitamins and minerals is the perception that they are harmless,” says Dr Moses.

“Like all medicines, supplements can cause potential harms, but unlike conventional medicines, manufacturers of vitamins and minerals are not required to provide warnings of their potential side effects, drug interactions or risks from overdose,” she says.

The article in Australian Prescriber discusses six potential harms of using dietary supplements.

1. They can have adverse effects, particularly at high doses.
2. They can interact with other medicines.
3. They cost money which may be better spent on other things.
4. Time spent taking dietary supplements may delay more effective treatments.
5. They may bring false hope and disappointment.
6. By taking dietary supplements, people add to the number of medicines they are taking, increasing the risk of medication error, interactions and adverse effects.

“What many people don’t realise is that high doses of some supplements can be dangerous. Indeed some of these supplements are regulated as prescription drugs because of this risk,” says Dr Moses.

“Another thing to remember is that the same vitamin or mineral can be in multiple different products, so a person can accidentally overdose if those products are all taken together,” she says

For example, vitamin A is in many products and taking too much vitamin A can result in skin peeling, liver impairment and loss of vision.

The article lists possible adverse effects of commonly used vitamins and minerals including vitamins A, B₃, B₆, C, D and E, calcium, magnesium, zinc and selenium.

Read the article in Australian Prescriber