TORONTO, CANADA. Folates (derivatives of folic acid) play a key role in the synthesis,
repair, and methylation of DNA. It is therefore not surprising that a deficiency in this
essential B vitamin has been implicated in Alzheimer's disease, atherosclerosis, heart
attack, stroke, osteoporosis, depression, dementia, cleft lip and palate, hearing loss,
Raynaud's phenomenon, and of course, neural tube defects.
There is now also evidence that a folate deficiency may be involved in the development of
certain cancers. Dr. Young-In Kim, MD of the University of Toronto presents an overview
of the current knowledge regarding the role of folates in cancer prevention. Some 20
studies have been published regarding the association between colorectal cancer (cancer
of the colon or rectum) and folate status. Collectively, these studies suggest that people
with a high intake of folates can reduce their risk of developing colorectal cancer by about
40 per cent when compared to people with low intakes. A study involving almost 90,000
American female nurses concluded that nurses who had been supplementing with 400
micrograms/day or more of folic acid for 15 years or more had a 75 per cent reduction in
the risk of colorectal cancer when compared to people who did not supplement.
The evidence concerning folates and breast cancer is not quite as clear. Studies have
shown that even moderate alcohol consumption increases the risk of breast cancer and
that this risk can be counteracted by supplementing with folic acid. The jury is still out on
whether folate supplementation reduces the risk among non-drinkers although one study
did show that postmenopausal women could decrease their risk of developing breast
cancer by supplementing with folic acid. Another study involving 300 premenopausal
women found a 50 per cent lower risk among women whose intake exceeded 304
micrograms/day. Other studies, however, have failed to confirm this effect.
A major study involving over 29,000 male, Finnish smokers found that those who
developed pancreatic cancer had a significantly lower blood serum level of folate than did
those who did not. A baseline serum folate level above 4.45 ng/mL was associated with a
55 per cent risk reduction when compared to levels below 3.33 ng/mL. An Australian
study found a 64 per cent difference in risk between men with the highest folate intake and
those with the lowest intake.
Dr. Kim concludes that a moderate increase in folate intake can materially help reduce the
risk of certain cancers, but cautions that people who already have cancer should not
increase their folate intake as there is evidence that high folate levels may accelerate the
growth of existing tumours.
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