Blood levels of vitamin folate in women of childbearing age decreasing

From 1999 through 2004 there was an 8% to 16% decline in the level of the vitamin folate in the blood of U.S. women of childbearing age, according to a study published in the Jan. 5 issue of CDC's Morbidity and Mortality Weekly Report, the AP/Houston Chronicle reports (Stobbe, AP/Houston Chronicle, 1/4).

In 1992, the U.S. Public Health Service recommended that all women of childbearing age consume 400 micrograms of folic acid daily, and FDA in 1996 required all enriched cereals to be fortified with the vitamin (Kaiser Daily Women's Health Policy Report, 3/19/01). Only one-third of U.S. women of childbearing age consume the recommended amount, Joseph Mulinare, CDC epidemiologist and lead author of the MMWR study, said (Stobbe, AP/Houston Chronicle, 1/4). For the study, Mulinare and colleagues compared data from CDC's National Health and Nutrition Examination Survey to assess trends in serum folate and red blood cell folate levels in U.S. women of childbearing age from 1999 through 2004 (Mulinare et al., MMWR, 1/5). The study involved home interviews, annual physical examinations and blood tests of about 4,500 women ages 15 to 44 (AP/Houston Chronicle, 1/4). According to the study, median serum folate levels declined by 16% from the 1999-2000 testing period and through the 2003-2004 testing period. The median serum folate concentrations declined significantly among non-Hispanic whites, non-Hispanic blacks and Mexican Americans, with the largest decrease -- 16% -- among non-Hispanic whites. The median serum folate concentration was lowest among non-Hispanic blacks in all survey periods. The study also found that red blood cell folate concentrations dropped by 8% during the two time periods (MMWR, 1/5).

According to the AP/Chronicle, it remains unclear why blood folate levels declined during this period, but some experts said there are several possible explanations, such as an increase in obesity rates among U.S. women of childbearing age. Nancy Green, medical director for the March of Dimes, said that research has shown that obese people metabolize folate differently than those with healthier weights and that some doctors think overweight women require more folic acid to prevent neural tube defects. An increased popularity of low-carbohydrate diets might also be a reason because women who reduced their carbohydrate intake might also have consumed less folic acid, Mulinare said. He added that vitamins and dietary supplements are the best way to get the recommended daily dose, as well as eating breads, cereals and other products containing enriched flour (AP/Houston Chronicle, 1/4).

The MMWR study is available online.