Can vitamin C block cancer drugs?
Publication Date:02/10/2008
An early laboratory study using mice suggests that high doses of vitamin C might stop cancer drugs from working so well. It’s too soon to say whether cancer treatments in people would be affected in the same way. Cancer patients are already advised not to take any vitamin supplements or herbal medicines without checking with their doctors first.
What do we know already?
Almost 30 years ago, some researchers suggested that vitamin C might actually help to cure cancer. As a result, vitamin C became very popular, with many people thinking it could prevent or treat cancer. But since the early research, the picture has become less clear. There’s no good-quality research proving that vitamin C can help treat cancer.
Chemotherapy drugs, radiotherapy and surgery are the main treatments for people with cancer. They work well and have helped many people survive cancer over recent decades. Chemotherapy aims to kill cancer cells.
We don’t know how vitamin C and chemotherapy drugs react with each other. Because of the way some chemotherapy drugs work, doctors are concerned that vitamin C might have an effect on them. So research is being done to find out more.
What does the new study say?
The new study found that mice with cancers that were injected with high levels of vitamin C got less benefit from the chemotherapy drug doxorubicin. Compared with mice that had not been injected with vitamin C, their tumours grew faster and were less likely to be kept under control by the drug.
Tell me more about the study's findings
The researchers also looked at individual cancer cells to see what was happening inside them. They found that structures called mitochondria (which make energy inside cells) were less likely to be damaged by chemotherapy drugs if the cancer cells had been treated with vitamin C. All cells, including cancer cells, die if their mitochondria aren’t working properly.
The researchers tested several different types of commonly-used chemotherapy drugs on the cancer cells. They found vitamin C interfered with they way they all worked. The drugs tested were cisplatin, doxorubicin, imatinib, methotrexate and vincristine.
Where does the study come from?
The study was carried out by researchers at the Memorial Sloan-Kettering Cancer Center in New York. It was published in the journal Cancer Research, which is owned by the American Association of Cancer Research. It was funded by the New York State Department of Health and by grants from the National Institutes of Health and several charitable foundations.
How reliable are the findings?
Because the study was carried out in the laboratory on mice and cancer cells, we can’t say whether the results are reliable for people with cancer. People often react to drugs in very different ways from mice.
However, it makes sense to avoid doing anything that could stop your cancer treatment from working as well as possible. Many doctors already advise cancer patients not to take vitamin supplements during chemotherapy.
What does this mean for me?
If you’re healthy and take vitamin C, there’s nothing to worry about from this study. If you're being treated for cancer, it may be best to avoid vitamin C supplements while you’re having treatment. That’s because it’s best to be safe, even though the study doesn’t prove that vitamin C is harmful for people having cancer treatment.
What should I do now?
If you need cancer treatment and you take any types of supplements or herbal remedies, talk to your doctor. Ask whether it’s safe for you to carry on taking them. It may be best to stop them during your treatment. However, you do need to carry on eating a healthy diet, including plenty of fruit and vegetables. There’s nothing to suggest that eating vitamin C in food can do any harm.
From:
Heaney ML, Gardner JR, Karasavvas N, et al. Vitamin C antagonizes the cytotoxic effects of antineoplastic drugs. Cancer Research. 2008; 68: 8031-8038.
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