Folic acid can dramatically reduce the incidence of spina bifida and other birth defects

Sep 23 2004

Adding folic acid to food can dramatically reduce the incidence of spina bifida and other birth defects.

A study, published today in BMC Pregnancy and Childbirth, shows that the proportion of babies born with neural tube defects in the province of Newfoundland and Labrador dropped by 78% after the Canadian Government directed that folic acid must be added to flour, cornmeal and pasta. The study supports the continuation of this food fortification strategy.

The way that folic acid works to reduce the risk of neural tube defects in developing babies is poorly understood, yet the evidence that this vitamin is of benefit is clear. Since 1992, many health organizations have recommended that women take 400 micrograms of supplemental folic acid per day before conception and in the early weeks of pregnancy.

In 1998 the Canadian Government introduced the mandatory fortification of some foods with folic acid to help ensure that all women of childbearing age increased their intake of this vitamin.

Dr. Catherine McCourt, from the Population and Public Health Branch, Health Canada, and her colleagues from other Canadian institutes studied the effects of this folic acid fortification in women and babies from Newfoundland and Labrador. Historically, this province has one of the highest rates of neural tube defects in North America.

The researchers found that the food fortification increased the dietary intake of folic acid in the studied women of childbearing age by 70 micrograms per day, on average. The blood folate levels of these women and of the sample of seniors 65 years and older increased significantly.

The incidence of neural tube defects in the province reduced from an average of 4.36 defects per 1000 births between 1991 and 1997, prior to fortification, to an average of 0.96 defects per 1000 births between 1998 and 2001, once fortification was introduced.

Over the study period, the number of women aged between 19 and 44 who took folic acid supplements rose significantly from 17% to 28%. It was not possible in this study to determine the separate contributions of food fortification and supplement use to the decline in neural tube defects. Therefore, the authors stress that, “public education regarding folic acid supplement use by women of childbearing age should continue.”

There has been some debate about whether an increased intake of folic acid could mask the symptoms of vitamin B12 deficiency, a disorder that affects 10-15% of the population over 60. Yet this study provided no evidence for a deterioration in vitamin B12 status in seniors, and no evidence that improved levels of blood folate masked this vitamin deficiency.