A diet expert specialising in treating and preventing cancer has warned that supplement fiends could be putting themselves at risk of the disease. 

Nichole Andrews, 38, a Washington-based registered dietician and nutritionist specialising in oncology shared a video on social media explaining why vitamins can be toxic. 

She told her 316,000 Instagram followers that high doses of some vitamins can morph into harmful molecules called free radicals which can trigger the cascade of cell damage that leads to cancer.

Those who’ve survived cancer are particularly vulnerable due to their high genetic risk of a secondary tumours, she added.

‘Unfortunately, cancer survivors are preyed upon by many people who sell supplements.

‘They try to get you to take all these different supplements to say it’s the way to detox and reduce cancer.’

‘You can get a very high dose of a micronutrient with just a pill, whereas with food, you’re never gonna reach that toxic level,’ she added.

‘Don’t take supplements unless you have a true deficiency that your doctor will show and prove to you through lab results.

‘Supplements don’t decrease cancer risk, they can increase it with that very high level.’

Several studies echo her concerns and discourage taking vitamins in excessive amounts. 

One 2023 study published in The Journal of Clinical Investigation, suggested antioxidants such as vitamin C and E can actually help tumours grow. 

These two nutrients play a vital role: Vitamin C is important for wound healing and healthy skin, blood vessels, bones and cartilage; and vitamin E for eye health and immunity.

Vitamin C is found in foods such as broccoli citrus fruit and vitamin E is found in nuts and seeds.

While these vitamins are not a concern when consumed at the levels found in food, consuming more than your body needs by taking supplements could help cancer flourish. 

One study suggested antioxidants such as vitamin C and E can actually help tumours grow

Researchers at the Karolinska Institute, a medical university in Sweden, injected mice with lung cancer cells before feeding them increasing doses of vitamins C and E through their drinking water.

They then carried out regular ultrasound scans to monitor the formation of blood vessels that help the cancer cells to form a solid tumour.

Results showed the vitamins boosted a protein in the body that helped to increase the blood supply to tumours, helping them grow. 

Another 2015 review by experts at the University of Colorado found those who took extra vitamins and minerals were more likely to have health problems.

One particular vitamin beta carotene — a supplement advertised as a boost to the immune system — was found to increase the risk of developing lung cancer and heart disease by up to 20 per cent.

But that’s only when people took more than the recommended dosage of 7mg a day. 

The substance gives yellow and orange fruit and vegetables their colour and it’s turned into vitamin A in the body. 

However, in high doses, the vitamin can be dangerous and increase the risk of lung cancer in people who smoke or have been heavily exposed to asbestos at work, according to the NHS. 

Nicotinamide riboside (NR), a form of vitamin B3, is advertised as having anti-ageing effects, as well as being able to bring down high cholesterol and blood pressure.

But a study by the University of Missouri-Columbia on mice found NR increased the risk of breast cancer, and caused the disease to spread to the brain, which is fatal.

The supplement is converted by the body into nicotinamide adenine dinucleotide (NAD+), an enzyme which is key for giving cells energy. But cancer cells can also feed off this energy.

To test this theory researchers gave genetically engineered mice with cancer 400 times the standard recommended daily dose of 250mg of NR.

The researchers monitored their cancer cells, T cells (a type of ‘fighter’ white blood cell) and healthy tissue.

NR increased the spreading of cancer cells to the brain in nine out of 11 mice, compared to only three out of 12 mice in the control group not given the supplement.

When they applied the technique to breast cancer cells they found the risk of developing the cancer also increased.

In 2019, one of the UK’s top pharmacists and former Government advisor unleashed a scathing attack on supplements, declaring them ‘untested and unproven’.

Dr Paul Clayton, a clinical pharmacologist, told MailOnline: ‘Of all the vitamins, the multi-vitamins, omega 3, vitamin C tablets and the like, there is no evidence to support any of them.

‘The one thing they all have in common is they don’t work and have no evidence to support them. When you put any of these things to test, they don’t do anything.

‘These products are being sold by companies who don’t really know what they are selling, and being bought by customers don’t really know what they’re buying.

‘But it doesn’t really matter with nutritional supplements because they don’t really do anything anyway – only to the consumer’s wallet.’