News agencies are, appropriately, reporting on the finding that the average levels of folate in American women are falling. (e.g. Folate levels in young American women fall, could lead to rise in birth defects) The media are doing a pretty good job of putting this in context. I am happy to see that the subject is getting as much attention as it is. But it is so important, that I want to add some additional background information, in order to reinforce this crucial public health issue. For one thing, the news reports seem to be aimed at raising the alarm for women. But men need to pay attention, too.
The history is as follows: Once it was established that folate can help prevent birth defects, supplementation of grain products was mandated in the USA. This is detailed in an MMWR review from October 27, 2000:
In 1992, the U.S. Public Health Service (PHS) recommended that women of child-bearing age increase consumption of the vitamin folic acid to reduce spina bifida and anencephaly (neural tube defects [NTD]) cases (1). Since then, national efforts have been implemented to increase the use of dietary supplements containing folic acid (2). In 1996, the U.S. Food and Drug Administration (FDA) mandated that all enriched cereal grain products be fortified with folic acid (3). To assess levels of folic acid among childbearing-aged women, CDC compared serum and red blood cell (RBC) folate concentrations for childbearing-aged women who participated in the 1999 National Health and Nutrition Examination Survey (NHANES 1999) to childbearing-aged women who participated in the Third National Health and Nutrition Examination Survey (NHANES III, 1988--1994). The findings indicate substantial increases in serum and RBC folate concentrations among women of childbearing age.
Note: folate and folic acid are two slightly different forms of the same thing. The distinction between the two is not important in this context.
Once public education was undertaken in earnest, and manufacturers were required to put folic acid in enriched cereals, there were measurable benefits:
A rigorous program of public education and fortification of popular foods with folic acid in the United States has decreased the rate of neural tube defects by about 20% in just a few years.
Spina bifida is the most common type of a class of birth defects, known collectively as neural tube defects. There is a good review of this topic at the University of Wisconsin's site, if you want to know more about the types of neural tube defects, and the relationship to folate. (There are some unpleasant pictures of the site.) There is a less technical, more consumer-oriented review here.
The are two possible reasons for the improvement in levels of folate in women. Part of it could have been due to the public education efforts; part of it could have been due to increased governmental intrusion into business practices. But survey data show that the the public education effort did not change people's behavior very much, so it was probably due to the regulatory interventions.
But now, we hear that the progress is being lost. The CDC publication, Morbidity and Mortality Weekly Review (MMWR) reported yesterday:
During 2001--2002 and 2003--2004, median (50th percentile) serum folate concentrations among women aged 15--44 years were 11.4 ng/mL and 10.6 ng/mL, respectively. Thus, a statistically significant 16% decline was observed from 1999--2000 (12.6 ng/mL) through 2003--2004 based on comparison of geometric means (p<0.001) (Table 1). Similarly, RBC folate concentrations decreased 8%, from 255 ng/mL during 1999--2000 to 235 ng/mL during 2003--2004 (p=0.028).
The authors state that it is not clear why this is happening, but they have several hypotheses. I won't go into that here; it is all rather technical. Part of it may be a trend toward low-carbohydrate diets, because the mandated supplements are added to grain products. There is also some evidence that manufacturers, in some cases, are not adding as much folic acid as they used to. The evidence they cited is not strong, so I would not yet begin to condemn the manufacturers. But would it not be terribly disturbing, if it turned out that there were more babies born with spina bifida, because some companies wanted to save a few pennies?
Anyway, the bottom line is this: Even though the data show that public education does not help much, I am going to try to reinforce the message: all women of childbearing potential should make sure they are getting enough folate. This recommendation is not restricted to those who are trying to get pregnant. Nearly half of pregnancies in the USA are unintended. Get that? In case you don't, let me emphasize the point: all women who are capable of having children need to pay attention to this. I do not care if you have taken a virginity pledge. Those don't work, anyway. I don't care if you are sure you would get an abortion. People change their minds. Basically, there is no excuse for not attending to this.
Even males, who are sexually active with women who could get pregnant, need to pay attention to this. For the men (and boys, I guess) out there: it does not matter whether you intend for pregnancy to occur. It is your responsibility to understand that pregnancy might occur, and you better be ready to face the consequences.
Men cannot control the health-related behaviors of their sexual partners,but, they can exert a positive influence. Be responsible, guys.
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