Folic acid supplements raise cancer risk: study

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Folic acid supplements raise cancer risk: study

Tue Nov 17, 2009 6:59pm EST

By Steenhuysen

CHICAGO (Reuters) - Heart patients in Norway -- where unlike many countries

foods are not enriched with folic acid -- were more likely to die from cancer if

they took folic acid and vitamin B12 supplements compared with those who did not

take them, Norwegian researchers said on Tuesday.

The team found lung cancer rates were 25 percent higher among those who took the

supplements compared with the general population, but overall cancer deaths and

deaths from other causes were also higher in the supplement group.

They said folic acid given over a period of more than three years may feed the

growth of cancers that were too small to be detected otherwise, and raises new

questions about the benefits of fortifying foods with folic acid.

" Our results need confirmation in other populations and underline the call for

safety monitoring following the widespread consumption of folic acid from

dietary supplements and fortified foods, " Dr. Marta Ebbing of Haukeland

University Hospital in Bergen, Norway, and colleagues wrote in the Journal of

the American Medical Association.

Folic acid, a B vitamin, helps the body make healthy new cells, and getting

enough of it is crucial for women before pregnancy to prevent serious birth

defects like spina bifida.

FORTIFIED U.S. FLOUR

For this reason, many countries, including the United States, fortify flour and

grains with folic acid. But recent studies have raised concern that folic acid

may raise the risk of cancer.

Because there is no folic acid fortification of foods in Norway, the study

population offered a good way to test for the effects of folic acid on cancer

risk.

Ebbing and colleagues analyzed data from two large trials involving people with

heart disease who took folic acid and vitamin B12 supplements to try to lower

levels of the amino acid homocysteine, which has been linked with heart attacks

and strokes.

The three-year studies failed to show a heart benefit, but the team continued to

follow patients for over three years to see if the supplements had any effect on

cancer risk.

When they combined the findings from the two trials for a total of more than

6,800 patients, they found those who got folic acid and vitamin B12 supplements

had a higher risk of being diagnosed with cancer, of dying from cancer and of

dying from any other cause.

" These findings were mainly driven by increased lung cancer incidence, " the team

wrote.

They said since the study took place in a population that is normally not

exposed to folic acid, the findings raise concerns about the long-term effects

of folic acid supplements.

The study is not the first to suggest folic acid may increase a person's risk

for cancer. A study in March suggested that folic acid supplements raise the

risk of prostate cancer. And a study in April suggested that fortifying foods

with folic acid raised the risk of colon cancer.

In animal studies, the effects of folic acid have been inconsistent, with some

studies suggesting the supplements protect normal colon tissue while enhancing

the growth of abnormal tissue.

The team found no link between colon cancer risk and folic acid and said this

may suggest the dual effects of the supplements on this cancer cancel each other

out.

(Editing by Walsh)