Dr. Marta Ebbing told NutraIngredients.com that the study should be scrutinized closely by officials in Australia, which recently introduced mandatory folic acid fortification of wheat flour for breadmaking and in the UK, which has said that it plans to do so.
Heart patients in Norway, where foods are not fortified with folic acid, were more likely to die from cancer if they took folic acid and vitamin B12 supplements than those who did not take them, according to the research published in the Journal of the American Medical Association (JAMA).
The study recorded the mortality rates of 6,837 patients split into two groups over six-and-a-half years. One group received a 0.8mg folic acid and 0.4mg vitamin B12 supplement each day for three-and-a-half years and the other group did not.
Lung and prostrate cancer
“The research revealed an increase in all types of cancers (in the group taking the supplement) except colorectal cancer but lung and prostrate cancer were prominent,” said Dr Ebbing. Lung cancer rates were 59 per cent higher in those who took the supplements compared with those who did not. Deaths both from cancer and from other causes were also higher in the group taking the supplement.
Although Dr Ebbing’s research did not explore the reasons for the increase, she told NutraIngredients.com that other research had suggested that in stimulating cell division, folic acid may have provided existing cancer cells “the nutrition to grow.”
Since the study took place in a population that is normally not exposed to folic acid, the results support concerns about the long-term effects of folic acid supplements, she said.
Many countries, including the United States, fortify flour and grains with folic acid which is particularly beneficial for pregnant women or women hoping to become pregnant and in the prevention of serious birth defects such as spina bifida.
Further animal and human research was necessary to explore the link between folic acid and vitamin B12 and the enhanced risk of cancer, said Dr Ebbing. Writing in JAMA the research team concluded: "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."
Mandatory fortification
Monitoring cancer rates in Australia and the UK, if mandatory fortification is introduced, would also provide important information about the long-term effects of mandatory folic acid fortification, added Dr Ebbing.
Meanwhile, earlier this month scientists from a European Food Safety Association-led scientific cooperation project said a potential link between high folic acid intakes and increased risks of cancer can not be ruled out and called for closer monitoring.
EFSA’s Scientific Cooperation Working Group (ESCO) advised in a report on the risks and benefits of folic acid fortification of food that uncertainties relating to cancer risk highlight the importance of monitoring the impact of folic acid intake.
Source: Journal of the American Medical Association.
Published: Journal of the American Medical Association.
Title: Cancer Incidence and Mortality After Treatment With Folic Acid and Vitamin B12.
Authors: Marta Ebbing, MD; Kaare Harald Bønaa, MD, PhD; Ottar Nygård, MD, PhD; Egil Arnesen, MD; Per Magne Ueland, MD, PhD; Jan Erik Nordrehaug, MD, PhD; Knut Rasmussen, MD, PhD; Inger Njølstad, MD, PhD; Helga Refsum, MD, PhD; Dennis W. Nilsen, MD, PhD; Aage Tverdal, PhD; Klaus Meyer, PhD; Stein Emil Vollset, MD, DrPH