Fortifying foods with folic acid may not reduce the incidence of Down's syndrome, say University of Toronto researchers, although they suggest we may to need to wait for the next generation of women to give birth before their findings are confirmed.
Folic acid has been shown to dramatically decrease the incidence of neural tube defects, such as spina bifida, in newborns. It has also been suggested that the B vitamin could reduce incidence of Down's syndrome, found in the same at-risk families as neural tube defects by a recent study. But no such effect was observed in Canadian women, where mandatory fortification of cereal grains with folic acid was introduced in 1998, revealed the new study.
Dr Joel Ray and colleagues examined prenatal and postnatal incidence rates of Trisomy 21 (known as Down's syndrome) in Ontario, screening nearly 219,000 women prior to fortification and 118,000 women afterward. There was virtually no decline in the incidence of Trisomy 21 in relation to fortification, researchers reported in the recent issue of the American Journal of Medical Genetics Part A.
Ray said however that folic acid and vitamin B12 are essential for the proper development of genes, which lie in chromosomes and are copied as cells divide. The failure of folic acid fortification to impact Trisomy 21 could be explained by an insufficient folic acid intake or if Trisomy 21 originates before a woman is born.
"A woman's eggs are formed when she herself is a foetus in her mother's womb," said Ray. "So while taking folic acid may have no impact on the eggs of a woman now to prevent Trisomy 21, it may modify the eggs of her daughter to reduce the risk when she has her own child."
Both the US and Chile have also implemented mandatory folic acid fortification but in Europe campaigners for the policy have failed to convince governments. The UK's Food Standards Agency claims there are concerns that higher folic acid levels will negatively impact the health of the elderly. However studies in Canada and the US reveal a marked decline in children born with neural tube defects.