Folic acid 'speeds up breast cancer tumour growth'

High levels of folic acid have been shown to promote the growth of existing breast cancer tumours in laboratory tests. Scientists have found by testing on rats that the levels of folic acid that are typically consumed by cancer survivors and patients throughout North America actually promote the growth of breast cancer tumours.

Previous studies have suggested that folate and its synthetic form, folic acid, could actually be beneficial for patients that have been diagnosed with breast cancer. However, other research has found that taking high levels of folic acid might actually lead to the development of breast cancer. 

Views on the subject of the B vitamin and breast cancer are incredibly controversial but the most recent study has suggested that high levels of the supplement could be detrimental to cancer patients.  

Researchers at St Michael's Hospital, Toronto, Canada, led by Dr Young-In Kim, found during laboratory testing on rats that folic acid, when given in supplements that contain 2.5 times the recommended daily dose, "significantly promotes" the growth of cancerous cells in mammary glands that were previously present.

The discovery is an important one as people living in North America are exposed to high levels of the B vitamin through folic acid fortification in food, said Dr Kim. There is also a trend of high uses of vitamin supplements after the diagnosis of cancer.

In the last 15 years the amount of folic acid consumed by residents of North America has increased. Women that are attempting to conceive and pregnant women are advised to take folic acid supplements in a bid to prevent a number of birth defects. Food manufacturers are also required to add folic acid to a number of different products by the US and Canadian governments, further increasing intake.

In addition to these consumption habits, high numbers of residents take supplements that include folic acid for health benefits that have not yet been proven conclusively. All of these factors could, based upon the study, increase the likelihood of a faster growing breast cancer tumour.