This most recent study pertains to Canada. It shows that Canada also has been making progress. Moreover, it shows a corresponding decrease in the incidence of neural tube defects after grain product supplementation was instituted.
From the Canadian news:
Folic acid fortification cut birth defect rates
Thu. Jul. 12 2007
CTV.ca News Staff
In the 10 years since Canadian food manufacturers began fortifying their grain-based products with folic acid, the rate of spina bifida and other neural tube birth defects has been cut in half, a new study reveals.
The news reports are based upon a study published in the New England Journal of Medicine:
Reduction in Neural-Tube Defects after Folic Acid Fortification in Canada
Philippe De Wals, et. al.
Volume 357:135-142; July 12, 2007; Number 2
Background In 1998, folic acid fortification of a large variety of cereal products became mandatory in Canada, a country where the prevalence of neural-tube defects was historically higher in the eastern provinces than in the western provinces. We assessed changes in the prevalence of neural-tube defects in Canada before and after food fortification with folic acid was implemented.
Methods The study population included live births, stillbirths, and terminations of pregnancies because of fetal anomalies among women residing in seven Canadian provinces from 1993 to 2002. On the basis of published results of testing of red-cell folate levels, the study period was divided into prefortification, partial-fortification, and full-fortification periods. We evaluated the relationship between baseline rates of neural-tube defects in each province and the magnitude of the decrease after fortification was implemented.
Results A total of 2446 subjects with neural-tube defects were recorded among 1.9 million births. The prevalence of neural-tube defects decreased from 1.58 per 1000 births before fortification to 0.86 per 1000 births during the full-fortification period, a 46% reduction (95% confidence interval, 40 to 51). The magnitude of the decrease was proportional to the prefortification baseline rate in each province, and geographical differences almost disappeared after fortification began. The observed reduction in rate was greater for spina bifida (a decrease of 53%) than for anencephaly and encephalocele (decreases of 38% and 31%, respectively).
Conclusions Food fortification with folic acid was associated with a significant reduction in the rate of neural-tube defects in Canada. The decrease was greatest in areas in which the baseline rate was high.
This is another instance of a very inexpensive intervention that makes huge difference.
More specifically, the supplementation began in 1997. In 1998 there were detectable improvements in blood samples drawn from the general population. The improvements plateaued in 1999. Unfortunately, the study does not extend to the present time, so we do not know if Canadians have started to show a reversal of progress, as has been demonstrated in the United States.
Neural tube defects are not the only problems associated with low folate during gestation (Folic acid: influence on the outcome of pregnancy):
During pregnancy, low concentrations of dietary and circulating folate are associated with increased risks of preterm delivery, infant low birth weight, and fetal growth retardation. A metabolic effect of folate deficiency is an elevation of blood homocysteine. Likewise, the presence of maternal homocysteine concentrations have been associated both with increased habitual spontaneous abortion and pregnancy complications (eg, placental abruption and preeclampsia), which increase the risk of poor pregnancy outcome and of decreased birth weight and gestation duration.
Currently, it is standard practice to start women on prenatal vitamins when it is know they are pregnant. But the time of greatest vulnerability is when during the first few weeks of pregnancy, at a time when the pregnancy likely has not been detected yet. Therefore, the best recommendation is for women with childbearing potential to take a decent multivitamin on a daily basis. Note the the current FDA recommendation is to not exceed 1,000 micrograms of folate (1 milligram) per day. Also note that, in their ruling, they noted that the evidence establishing a safe upper limit is not solid. Part of the concern is that higher levels can mask the precence of a deficiency of vitamin B12, as is seen in pernicious anemia, among other conditions. (This is particularly important for people who eat only plants.)
So, as I mentioned, this is not really news. The salutary effects of folic acid during gestation were well established prior to the Canadian study. Still, it is good to see a study that provides evidence of improved clinical outcomes, and it is a good reminder of a critical piece of public health information.
Comments
nıce plugın
Posted by: evden eve nakliyat | October 19, 2007 11:33 PM
no, a 75% reduction (95% confidence interval, 40 to 51).
Posted by: Evden Eve Nakliye | November 7, 2007 5:50 AM