An injection of a high dose of vitamin C may be able to hold back the advance of cancers, US scientists claim.

The vitamin may start a destructive chain reaction within the cancer cell, they add.

The jab halved the size of brain, ovarian and pancreatic tumours in mice, reported the journal Proceedings of the National Academy of Sciences.

However, Cancer Research UK said other studies suggested large vitamin C doses may interfere with cancer treatment.

Earlier research by the team at the National Institutes of Health in Maryland had suggested that the vitamin, also called ascorbate, could kill cancer cells in the laboratory.

After these successful tests in mice, they are now suggesting that the treatment be considered for human use at similar levels.

The dose they employed - up to four grams per kilo of bodyweight - was far greater than any that could be achieved using diet or vitamin pills, as the digestive system does not absorb more than a fixed amount taken orally.

The mice were bred to have malfunctioning immune systems, then injected with human cancer cells, which as a result, grew quickly into large tumours. The vitamin was then injected into their abdominal cavity.

Tumour growth and weight fell by between 41% and 53%, and while in untreated mice, the disease spread rapidly to involve other body parts, no such spread was seen in the vitamin C-treated animals.

The researchers wrote: "These pre-clinical data provide the first firm basis for advancing pharmacologic ascorbate in cancer treatment in humans."

Peroxide bomb

The treatment works because a tumour cell is chemically different to a healthy cell.

The vitamin C reacts with this chemical make-up, producing enough hydrogen peroxide to kill the cell, while leaving healthy cells unscathed.

However, Dr Alison Ross, from Cancer Research UK said that much more work would have to be done to see if vitamin C could be a viable treatment.

"This is encouraging work but it's at a very early stage because it involves cells grown in the lab and mice.

"There is currently no evidence from clinical trials in humans that injecting or consuming vitamin C is an effective way to treat cancer.