Folic Acid Does Not Increase Cancer Risk, Analysis Finds
Folic acid is the synthetic form of the B vitamin folate, fortified in US (and Canadian) flour to prevent neural tube defects. But previous observational studies suggested that the supplement may increase the risk for colon cancer among certain populations. Not so, finds a major new analysis published last week in The Lancet.
The analysis looked at the 13 randomized controlled trials completed before 2011. Including about 50,000 people in total, each the trials had compared people who took folic acid supplements daily for at least one year, comparing them to participants who had not taken a supplement. The trials had focused on either heart disease prevention or colorectal adenoma but all recorded data on cancer incidence.
On average, participants took the supplement for five years and cancer incidence remained about the same among the participants who did or did not take folic acid. There was no trend towards increased incidence with people who took the supplement for longer. When the authors looked at specific cancers, there was no significant effect of folic acid supplementation on cancer incidence of the large intestine, prostate, lung, breast, or any other specific site.
Folate, vitamin B9, is found naturally in dark green leafy vegetables, whole grains and legumes. No studies have linked foods containing folate with increased cancer risk.
The median daily dose people took in these trials was 2 milligrams, about four times greater than the average amount of folic acid in a daily multivitamin.
Source: Stein Emil Vollset et al. “Effects of folic acid supplementation on overall and site-specific cancer incidence during the randomised trials: meta-analyses of data on 50 000 individuals.” The Lancet, Early Online Publication, 25 January 2013.