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Low folate diets found to increase risk of colorectal cancer

November 03, 2006

A new study by scientists at the MUHC has revealed that a diet low in folate may increase the risk of developing colorectal cancer. Published in the scientific journal Cancer Research today, the study not only illustrates a way to prevent the disease but also provides further insight into the mechanisms of the disease, which could lead to novel therapies. Using animal models, the MUHC study is the first to demonstrate directly that diets low in folate cause colorectal cancer, and follows on the heels of earlier research by the same team that revealed how high folate diets can protect against heart disease.

"This research, which is consistent with previous epidemiological studies in humans, demonstrates a clear link between low dietary folate and the initiation of colorectal cancer in animal models," says Dr. Rima Rozen, Scientific Director of the Montreal Children's Hospital, Deputy Scientific Director of the MUHC, and lead investigator in the study. "None of the mice fed a control diet developed tumours whereas 1 in 4 mice on the folate-deficient diet developed at least one tumour."

Possible mechanisms of the disease were also investigated using molecular biological techniques. "The study shows that a low level of dietary folate may cause an increase in DNA damage, which plays a role in the development of tumours," noted Dr. Rozen. The study also reveals that folate deficiency causes genes which usually respond to DNA damage to behave abnormally, also contributing to the development of tumours. The results suggest that a diet containing sufficient folate may reduce the risk of developing colorectal cancer.

"It is estimated that 20,000 men and women will be diagnosed with colorectal cancer this year, and an estimated 8,500 will die from the disease. The result of this study highlights how simply adding a supplement to your daily diet could have tremendous long-term benefits to the individual and the health care system," said Dr. Philip Branton, Scientific Director of the CIHR Institute of Cancer Research. "While these results are encouraging, much more research will be needed before we will know for certain if folate has any protective effect for colorectal cancer in men," added Dr. Branton.

The intake of an adequate amount of dietary folate has also been shown to prevent a number of other diseases. "For example, birth defects such as Spina Bifida, can result in offspring of mothers with inadequate folate in their diet," says Dr. Rozen. In March of this year, the same team revealed how diets with the recommended levels of folate can protect against heart disease. "Obviously, this is not a reason to consume excessive amounts of folate, but rather to ensure that the recommended daily amount is taken through a healthy diet or a vitamin supplement," noted Dr. Rozen. The benefits of a high folate diet have been known for many years. Both the US and Canada have regulations requiring the addition of folic acid (the synthetic form of folate) to breads, cereals, flours, corn meals, pastas and rice to increase its intake in the general population.

Colorectal cancer affects approximately 5% of the population. The majority of cases are sporadic and due mainly to environmental factors. Hereditary forms can account for up to 15% of all colorectal cancers.

McGill University