CancerFolic Acid

The saga continues: Folic acid does not protect from colon cancer

The value of folic acid supplementation is not clear. This large study found no benefit. In fact, folic acid supplements might cause harm.

First, the details.

  • 1021 men and women had a recent history of colorectal adenomas and no previous cancer of the intestine.
  • An “adenoma” is a tumor of the colon or rectum that might develop into colorectal cancer over time.
  • They were randomly assigned to receive folic acid 1 mg/day or placebo.
  • Some received aspirin (81 or 325 mg/day), while others did not.
  • They were evaluated 3 years later and again 3 to 5 years after that.

And, the results.

  • During the first 3 years, the incidence of at least 1 colorectal adenoma was 44% for folic acid and 42% for placebo.
  • Progression of adenomas to an “advanced lesion” was 11% for folic acid and 9% for placebo.
  • Neither difference was significant.

At the second evaluation?

  • The incidence of at least 1 advanced lesion was 12% for folic acid and 7% for placebo.
  • That difference was significant.
  • Folic acid was associated with greater risk of having 3 or more adenomas and of noncolorectal cancers!
  • Adjusting the findings for any effect of gender, age, smoking, alcohol use, body mass index, baseline plasma folate, or aspirin treatment did not change the results.

According to researcher Dr. Bernard Cole from Dartmouth-Hitchcock Medical Center in New Hampshire and colleagues, “Folic acid at 1 mg/day does not reduce colorectal adenoma risk. Further research is needed to investigate the possibility that folic acid supplementation might increase the risk of colorectal neoplasia.”

The bottom line?
The results of research — and there’s lots of research — present a confusing picture of the effects of folic acid on the risk of getting colorectal cancer.

In a 2006 Reuters interview, Dr. Y-I Kim, from the University of Toronto commented, “Some proponents of mandatory folic acid fortification have labeled the delay in…fortification in European countries as public health malpractice.”

Now, it seems that the delay was prudent. Dr. Kim advised that “Long term follow-up studies are urgently warranted to determine the effect of folic acid fortification and supplementation on the incidence of cancer and other potential adverse effects.”

Results from this long-term study by Dr. Cole question the wisdom of using folic acid to reduce the risk of colorectal cancer. Many questions remain to be answered.

6/6/07 09:57 JR

Hi, I’m JR

John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at, a complementary and alternative medicine website.