Doctors urge caution when using a popular supplement if you’re at cancer risk – it may speed up tumor growth

Doctors have cautioned against using Vitamin C and E supplements if you are a cancer patient or someone with an elevated cancer risk.

A study on lung cancer cells found they stimulate the formation of new blood vessels in the tumor, which could speed up the growth and spread of cancer.

The researchers admitted their findings are ‘surprising’, given the vitamins were thought to be powerful protectors against cancer.

The antioxidants, commonly found in fruit and vegetables, reduce inflammation linked to cancer.

But they also generate the formation of new blood vessels in the body, including in cancer tumors.

Martin Bergö, a professor of molecular medicine from the Karolinska Institutet in Sweden, stressed that ‘there’s no need to fear antioxidants in normal food’ — as fruit and vegetables don’t contain enough — but said that people do not need additional amounts of them.

Vitamin C is known for its protective powers against skin damage, while vitamin E is needed by the body to boost its immune system to fight off bacteria and viruses.

‘We’ve found that antioxidants activate a mechanism that causes cancer tumors to form new blood vessels, which is surprising, since it was previously thought that antioxidants have a protective effect,’ said study leader Professor Bergö.

Antioxidants like vitamin C reduce the level of free oxygen radicals in the body — molecules produced when your body is exposed to things like radiation from the sun, which may play a role in heart disease, cancer and other diseases.

The research group had previously shown that antioxidants like vitamins C and E encourage the growth of lung cancer by stabilizing a protein named BACH1.

BACH1 is activated when the amount of free oxygen radicals drops, which can happen when extra antioxidants are added to the diet.

Now, the researchers have shown that the activation of BACH1 brings on the formation of new blood vessels, including in cancer tumors.

They studied small parts of lung cancer tumors taken from patients, as well as samples of human breast and kidney tumors and mice.

They found that in tumors where the BACH1 protein was activated by antioxidants, more new blood vessels were formed.

The scientists hope their research could lead to better treatments to prevent cancer tumors from growing.

Ting Wang, doctoral student in Professor Bergö’s group at Karolinska Institutet, said: ‘The next step is to examine in detail how levels of oxygen and free radicals can regulate the BACH1 protein, and we will continue to determine the clinical relevance of our results.

‘We’ll also be doing similar studies in other cancer forms such as breast, kidney and skin cancer.’