Joshua Miller says more studies needed to determine if supplements and fortified foods are safe
Does the B vitamin folic acid increase the risk of cancer? A well-publicized five-year study found that those who took high levels of the same dietary supplement that prevents crippling birth defects in babies did not have an increased risk of prostate, lung, breast, colon and other cancers.
But Rutgers nutritional scientist Joshua Miller says not so fast. The professor in the School of Environmental and Biological Sciences is challenging the claim, insisting that more long-term research needs to be done to determine whether high levels of folic acid – found in fortified cereals, breads and pastas, and also in vitamin supplements – is safe or hazardous to a person’s health.
In a written commentary response published in The Lancet, Miller and Cornelia Ulrich, of the German Cancer Research Center in Heidelberg, Germany, called for scientists to be cautious in regard to the findings.
“Although these findings would suggest that excess intake of folic acid, either from supplements or through (food) fortification, is of little concern with respect to increasing cancer incidence, the data should be viewed with caution,” Miller and Ulrich wrote.
In the study, which included almost 50,000 individuals enrolled in 13 clinical trials, researchers found no significant difference of a cancer risk between those taking high dosage supplements – with 7.7 percent of those receiving folic acid supplements developing malignancies compared with 7.3 percent of those who received a placebo.
But Miller, who is researching the effect folic acid has on the mammary glands of mice, said that because most cancers take between 10 to 20 years to develop, more research is needed to determine the long-term effects of increased folic acid consumption.
Nutritional scientist Joshua Miller says more research is needed to determine whether high levels of folic acid increase the risk of cancer.
“What we know is that if you don’t have cancer, getting extra folic acid is good for you and protects you,” Miller said. “But once that cancer develops, it needs folate – the natural form of folic acid – to grow, divide and proliferate. So by feeding already formed cancers a person could be accelerating the cancer’s progression.”
There has been a growing trend among health conscious individuals to take vitamins and folic acid supplements instead of simply getting natural forms of folate from eating leafy green vegetables like spinach, asparagus and lettuce and consuming the cereal, bread and pasta being fortified with the supplement.
The United States and Canada have required that flour be fortified with folic acid since 1998 when it was determined that a folate deficiency in pregnant women was causing birth defects. Since then there have been calls by groups like the American Medical Association and the March of Dimes to increase the level of folic acid fortification in flour – a change that would have to be approved by the Food and Drug Administration.
This week, a study in the Journal of the American Medical Association of 85,000 women in Norway – where flour and grains are not fortified with folic acid – reported that women who started taking folic acid supplements before they got pregnant were 40 percent less likely to have a child who developed autism.
Miller argues that folic acid is important for expectant mothers and also helps to prevent anemia as well as cognitive deficits and dementia in the elderly. Adding folic acid to food or promoting the safety of high levels of vitamin supplements for the wide-scale population would be premature, he says. Currently, the U.S. government recommends no more than 1.0 milligrams daily of folic acid. The daily amount of fortification through flour is estimated to be 0.2 milligrams.
Calling fortification in flour an effective public health initiative to prevent neural tube defects in pregnant women, Miller insists that he is not advocating it be stopped. But, he says, since there is not a definitive answer on how folic acid supplementation affects the rest of the population, increasing the dosage would not be wise.
“The message should be that the general population is getting a significant amount of folic acid in cereal, pastas and other grains and they shouldn’t need to take other folic acid vitamin supplements,” he said. “This study is important but there is more to do and I don’t think the story is over yet.”