A new study published Friday in The Lancet has cast doubt on the idea that taking folic acid supplements regularly can lead to cancer. The study found that the difference in the overall incidence of cancer among those who consume high amounts of folic acid regularly and those who do not is not statistically significant.
Researchers looked at data for some 50,000 people collected over five years in 13 different randomized studies to reach their conclusions. They found that folic acid did not "increase or decrease" the risk of developing cancer in general, nor did it appear to have an effect on site-specific cancers such as colon, breast, lung, or prostate cancer.
This study is important because research in recent years has appeared to show a link between folic acid and certain types of cancer. Many countries, the United States in particular, require flour to be fortified with folic acid because of the folate's known ability to reduce birth defects, specifically neural tube defects like spina bifida.
But research published as recently as last year had cast doubt as to whether or not consuming folic acid in higher amounts over longer periods of time ended up having a negative effect on the body. Researchers had published a study in BMJ Open in January of 2012 after conducting a meta-analysis of their own that concluded that folic acid could cause an increased risk of developing cancer. Specifically, that study, which looked at data from 19 other trials involving some 4,000 people, concluded that consuming high amounts of folic acid over time could increase a person's overall risk of developing cancer, and of developing prostate cancer in particular.
A different study published in the Journal of the American Medical Association (JAMA) in November of 2009 had reached similar conclusions. That study had found that consuming high amounts of folic acid over time did appear to increase a person's risk of developing cancer, in particular lung cancer, and that it also increased a person's risk of "all-cause mortality."
The meta-analysis published in The Lancet analyzed data from a wider pool of research than either the JAMA study or the BMJ Open study. Even so, as nutrition researcher Joshua Miller of Rutgers University told Reuters that same day, there are enough questions still remaining as to folic acid's more long-term effects that people "should be a little cautious" about their intake, and not exceed the daily recommended dose of the folate.
Vanessa Evans is a musician and freelance writer based in Michigan, who frequently writes about health and nutrition topics.