Researchers from the Harvard School of Public Health analyzed data from the US Food and Drug Administration's third National Health and Nutrition Examination Survey to calculate folate intake across gender, age and racial groups.
The study, published in October's American Journal of Public Health, concluded that since fortification was implemented folic acid intake has in fact increased but that there are substantial variations across segments of the population.
Folate is found in foods such as green leafy vegetables, chick peas and lentils, and it is increasingly accepted that folate deficiency in early pregnancy is linked to a risk of neural tube defects such as spina bifida and anencephaly in infants.
This connection led to the introduction of public health measures in the US and Canada, whereby all grain products are fortified with folic acid - the synthetic, bioavailable form of folate.
The study assessed that none of the subgroups met the FDA's goal of bringing 50 percent of women up to the daily-recommended intake levels. Despite significant improvements and widespread fortification, only 39 percent of white women, 26 percent of black women, and 28 percent of Mexican American women attained the 400 microgram per day target for folate consumption.
Also, according to the researchers, over half the subgroups showed evidence of a decrease in folic acid intake after the federal fortification program began.
In the study, the Harvard scientists estimated the mean food and total folate intake increased by approximately 100 micrograms per day after fortification. But the average increases were higher among whites than black or Mexican Americans.
The FDA recommends 400 micrograms of folate daily for nonpregnant women, as well as children four and older, and adult men. However, the daily recommendation for pregnant women catapults to 800 micrograms.
The results are not only noteworthy given the fact women were recently found to be much more aware of folic acid than other nutrients recommended during pregnancy. In a survey of 500 women, the Society for Women's Health Research found 87 percent knew the importance of folic acid.
The study was published on-line ahead of print in the American Journal of Public Health (doi: 10.2105/AJPH.2005.067371)
Bentley et al. "Population-level changes in folate intake by age, gender, and race/ethnicity after folic acid fortification." American Journal of Public Health. October, 2006.