The research, published in the Journal of the American Medical Association (JAMA), revealed that 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.
Lung cancer rates were 59 per cent higher in those who took the supplements compared with those who did not, according to the study conducted at Haukeland University Hospital, Bergen, Norway.
But the Council for Responsible Nutrition (CRN) and the Health Food Manufacturers'Association(HFMA) claim that the research reveals the dangers of smoking not of taking folic acid and vitamin B12 supplements.
Lung cancer
Andrew Shao, CRN’s vice president, scientific and regulatory affairs, said: “The real headline of this study should be that smoking increases the risk of lung cancer. The study found that a total of 94 per cent of the subjects who developed lung cancer were either current or former smokers. Most health experts would agree that the number one way to prevent lung cancer is to abstain from smoking.”
The results are inconsistent with the larger body of data and any link between folic acid and vitamin B12 supplements has not been observed previously, he added.
“Given that mandatory folic acid fortification went into effect in the United States in 1998, if high doses of folic acid have a paradoxical effect on lung cancer, then we likely would not have seen these drastic reductions in lung cancer incidence over the past two decades. It is inappropriate at this point to reach firm conclusions based on such limited data, especially in the face of vast evidence showing benefit for folic acid supplementation,” said Shao.
Graham Keen, HFMA executive director, said: "The main reason for the finding of increased incidences in the Norwegian study is due to lung cancer. 40% of the subjects were current smokers and of all the lung cancer diagnoses, 70% were in current and 24% in former smokers. The main concern of this study had been a possible link with colorectal cancer - a link that was not found."
Overwhelming evidence
"There is an overwhelming body of evidence supporting the role folic acid plays in many groups, specifically pregnant women, where it helps to prevent birth defects such as spina bifida," said Keen.
Peter Engel, spokesperson of DSM Nutritional Products Europe told NutraIngredients.com that the authors found a non-statistically signficant association between folate treatment and cancer incidence and mortality at folate acid supplemenation levels 4-6 fold higher than those achieved with mandatory fortification.
“In terms of primary outcomes, colorectal cancer incidence and mortality, subjects in the 2nd quartile of serum folate levels (3.8-10.6 ng/mL) had the lowest incidence and risk of colorectal cancer mortality, lower than that in Quintile 1,” wrote Engel in statement. “This provides evidence that achieving adequate folate status (Quintile 2 vs Quintile 1) protects against both development and promotion of cancer whereas pharmacologic doses may not.”
Also current evidence shows that average folic acid intake in United States adults is inversely related to cancer incidence, Engel pointed out. Prospective analyses indicate that US fortification of foods with folic acid was associated with 50% reductions in mortality risk from colorectal cancer
The Norewegian study was entitled Cancer Incidence and Mortality After Treatment with Folic Acid and Vitamin B12.