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Nutrition, Vitamins & Supplements for Seniors
Is the Government Increasing Your Risk for Colon
Cancer? Urgent Need for Research
Plea by co-author of JAMA report that folic acid
supplements do not prevent colon cancer but may increase risk
 June 9, 2007 In view of new research showing
folic acid supplements do not reduce the risk of precancerous tumors in
the colon and may even increase the risk the government may be
contributing to this risk due to its mandate that folic acid be added to
foods such as bread, flour and pasta. Research into this possibility
should be a high priority, according to Robert Sandler, M.D., a
co-author of the study.
We had great hope that folic acid would be a very
cheap and effective agent to prevent large bowel adenomas. We expected
that folic acid would decrease the risk for colorectal cancers, perhaps
as much as 40 percent. So these results are disappointing, said Sandler,
chief of the division of gastroenterology and hepatology in the
University of North Carolina at Chapel Hill School of Medicine.
In addition, the government-mandated addition of
folic acid to common grain-based foods such as bread, flour and pasta
may be a contributing factor to increased risk and thus research into
this possibility should have a high priority, the study authors
concluded.
Sandler said there is no reason for people to think
that fortified foods are risky and should be avoided. At the same time,
he said, there is now reason to doubt that folic acid fortification will
prevent colorectal cancer, which is one of the more common cancers.
Women who are contemplating pregnancy or in early
pregnancy should continue to seek out folic acid-fortified foods and
take supplements, Sandler said. The rest of us should await more data
before we change our eating patterns or before policymakers revisit food
supplementation.
The study appears in the June 6, 2007, issue of the
Journal of the American Medical Association. The lead author is Bernard
F. Cole, Ph.D., of Dartmouth Medical School. The research took place at
nine clinical centers, including UNC, between 1996 and 2004.
Partial funding for the study was provided by the
National Institutes of Health. Folic acid supplements provided to
patients during the study were provided by Wyeth Consumer Health Care.
Previous research has shown that taking folic acid
supplements significantly reduce the incidence of neural tube defects,
such as spina bifida, in newborns. For this reason, the Food and Drug
Administration required the addition of folic acid to many grain-based
foods starting in 1998. Earlier studies also suggested that folic acid
might play a role in preventing colorectal cancer.
To investigate folic acid supplements effects on
colorectal cancer, Cole and his colleagues recruited 1,021 men and women
who had previously been treated for adenomas (precancerous colon tumors)
to take part in the clinical trial. The patients were randomly assigned
to take one milligram of folic acid a day or a placebo. They were also
separately randomized to receive aspirin, in doses of either 81 or 325
milligrams a day, or placebo. Study participants had two follow-up
colonoscopies to check for tumors. The first colonoscopy was three years
after the participant joined the trial. The second interval was three to
five years later.
The results showed little difference between the
number of tumors found in the folic acid and placebo groups. In the
first follow-up interval, tumors were found in 42.4 percent of the
placebo group and 44.1 percent of the folic acid group. In the second
follow-up interval, 37.2 percent in the placebo group had precancerous
tumors compared to 41.9 percent in the folic acid group.
However, people in the folic acid group had higher
rates of advanced tumors and multiple tumors. They were more than twice
as likely as those in the placebo group to have three or more
precancerous tumors. A higher rate of non-colorectal cancers, primarily
prostate cancer, was also found in the folic acid group.
We found no clear evidence that folic acid
supplementation provided any health benefits, the researchers wrote.
They also noted that fortification of the food supply with folic acid
may have affected their results, and that the evidence of increased risk
was equivocal and thus requires further research.
In view of the fortification of the U.S. food
supply with folate, and some suggestions that folate could conceivably
increase the risk of neoplasia even outside the bowel, this line of
investigation should have a high priority, the study concluded.
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