Folate levels dropping
Fashion for non-processed foods could cut vitamins and boost birth defects.
Women in the United States are not eating enough folate, says a survey by government researchers. According to the study's authors, two-thirds of women do not eat the recommended daily amount of the vitamin, which helps to prevent severe birth defects. And levels of folate in the diet have actually declined since 1999, they report.
The decline may be due to increased consumption of wholegrain breads and cereals, which are not fortified with folate, says Joseph Mulinare of the National Center on Birth Defects and Developmental Disabilities in Atlanta, Georgia, who led the survey. He suggests that all women of childbearing age take supplements of the related compound folic acid, even when not pregnant.
The US Public Health Service recommends that women consume 400 micrograms of folic acid per day to help prevent developmental problems called neural tube defects, which occur early in pregnancy and give rise to crippling conditions such as spina bifida and anencephaly.
During the late 1990s, rates of such defects in the United States fell to roughly 3,000 per year, a 25% drop compared with levels in the previous decade. This improvement is thought to have been a product of the government's decision to promote folate; by 1998 they had made it compulsory for 'enriched' foods to contain folate, as well as a suite of other vitamins.
But ironically, the fashion for non-processed wholegrain foods means that folate consumption has now begun to fall. On average, women now consume only around 150 micrograms per day less than half the recommended amount, Mulinare says.
He and his colleagues looked at more than 4,500 measurements of blood folate levels from women aged between 15 and 44. From 1999 to 2004 they saw variable declines of up to 16%, with the greatest drop seen for white non-hispanics, they report in Morbidity and Mortality Weekly Report1.
It is too early to say whether this decline has caused an increase in birth defects, Mulinare says. But he recommends that women of childbearing age take daily folic acid tablets, which he says would cost between US$5 and $15 per year, to boost their intake.
Health experts recommend that women take folate supplements even when not pregnant. Because the neural tube is one of the first structures to form in the developing embryo, by the time a women discovers she is pregnant it is already too late, Mulinare says. He also points out that at least half of pregnancies in the United States are unplanned.
Fortification of processed foods with folate has been controversial, because the compound has been linked to Alzheimer's disease and other conditions that can affect other population groups, such as the elderly. But Mulinare says that health officials have made a conscious effort to ensure that the amounts of folate found in processed foods does not pose a threat to overall health.
Although the trend towards wholegrain eating and low-carb diets has stunted women's average folate intake, there are other foods, such as broccoli, spinach or yeast products, that offer a natural dose. "But you would have to eat a very large portion of broccoli or spinach," Mulinare says.
"We recommend all three ways: a natural diet, a supplement, and fortified foods," he says. "But a pill is easiest trying to change behaviour is more difficult."
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- Boulet S. L., Yang Q., Mai C., Mulinare J.& Pfeiffer C. M. Morbidity and Mortality Weekly Report, 55. 1377 - 1380 (2007).
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