The neural tube defects anencephaly and spina bifida are serious and common birth defects that affect one in 500 to 1,000 pregnancies.

A 1991 randomized trial showed that increasing the intake of folic acid before a woman conceives and in the early stages of pregnancy can prevent most cases of these birth defects.

Folic Acid Fortification Reduced Prevalence Of Birth Defects

 A folic acid is a synthetic form of B vitamin folate, which plays an important role in the production of red blood cells. For this reason, the United States and 80 other countries have made it mandatory to fortify cereals with folic acid, thereby reducing the prevalence of neural tube defects by half.

Unlike many other countries, the United Kingdom, however, did not introduce folic acid fortification, partly because it is concerned that people would take folic acid above the so-called upper limit.

Tolerable Upper Intake Level For Folate

The tolerable upper intake level for folate as suggested by the US Institute of Medicine is the amount of folate that a person can take without it causing harmful side effects. The IOM analyzed studies involving people with B12 deficiency who were wrongly treated with high doses of folic acid. It concluded that higher doses of folic acid may result in having higher odds for neurological damage.

Findings of a new research, however, found that there is no need for an upper limit of folate intake. Study researcher Nicholas Wald from the Wolfson Institute of Preventive Medicine, who was also the lead researcher of the 1991 study, and his colleagues reanalyzed the data and found no link between high levels of folic acid and neurological damage. The researchers said that the damage was actually caused by not having enough levels of B12.

"The upper limit should be discarded," the researchers wrote in their study. "This would have the practical effect of leaving no scientific obstacle to the introduction of mandatory folic acid fortification in all countries, which would have an important global impact on the prevention of neural tube defects."

UK's Fears Are Unjustified

Health experts said that the study, which was published in the journal Public Health Reviews on Wednesday, showed that UK's fears were unjustified. Now, there is no more reason for the country to delay the imposition of a mandatory folic acid fortification.

Wald said that not fortifying flour with folic acid to prevent birth defects is similar to having polio vaccine and not using it.