The scientists from the National Institutes of Health in Maryland believe the vitamin may react with the chemicals in cancer cells to produce acid which then destroys the tumour and works because a tumour cell is chemically different to a healthy cell.
The reaction between the two produces sufficient hydrogen peroxide to kill the cell, while leaving healthy cells unharmed.
The researchers say the high doses of vitamin C reduced the growth of aggressive tumours by between 41% and 53% in mice bred to develop brain, ovarian and pancreatic tumours.
The mice used were bred to have malfunctioning immune systems, then injected with human cancer cells, which as a result, rapidly grew into large tumours.
When the vitamin was injected into their abdominal cavity, tumour growth and weight fell significantly... while in untreated mice, the disease spread rapidly to involve other body parts, but no such spread was seen in the vitamin C-treated animals.
The same team previously conducted research which suggested that the vitamin, also called ascorbate, could kill cancer cells in the laboratory and the success of the tests with mice has led them to suggest that the treatment should be considered for human use.
The dose used equates to four grams per kilo of bodyweight and could not be achieved using diet or vitamin pills, as the digestive system does not absorb more than a fixed amount taken orally.
The researchers say the pre-clinical data provides the first firm basis for advancing pharmacologic ascorbate in cancer treatment in humans.
However experts say while the research is encouraging, it is at a very early stage and other studies have in fact suggested that large doses of vitamin C may in fact interfere with cancer treatments by reducing the benefits of radiotherapy and chemotherapy.
They say much more work needs to be done to see if vitamin C could be a viable treatment.
The study is published in the Proceedings of the National Academy of Sciences.
Produce from the organically and conventionally grown crops were then fed to animals over a two year period and intake and excretion of various minerals and trace elements were measured. Once again, the results showed there was no difference in retention of the elements regardless of how the crops were grown.
Dr B gel says: 'No systematic differences between cultivation systems representing organic and conventional production methods were found across the five crops so the study does not support the belief that organically grown foodstuffs generally contain more major and trace elements than conventionally grown foodstuffs.'
Dr Alan Baylis, honorary secretary of SCI's Bioresources Group, adds: 'Modern crop protection chemicals to control weeds, pests and diseases are extensively tested and stringently regulated, and once in the soil, mineral nutrients from natural or artificial fertilisers are chemically identical. Organic crops are often lower yielding and eating them is a lifestyle choice for those who can afford it.'
This research was supported by the International Centre for Research in Organic Food Systems (ICROFS), Denmark.
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