TABLE 2.
Prefortification (1988–1994) and postfortification (1999–2010) proportions of low blood folate concentrations by sociodemographic variable, dietary supplement use, and survey period in participants aged ≥4 y (NHANES 1988–2010)1
|
Serum folate <10 nmol/L |
RBC folate <340 nmol/L |
|||
| 1988–1994 | 1999–2010 | 1988–1994 | 1999–2010 | |
| % | ||||
| Total | 23.8 ± 1.0 | 0.7 ± 0.1 | 3.5 ± 0.3 | 0.1 ± 0.0 |
| Age group | ||||
| 4–11 y | 2.8 ± 0.4 | —2 | 0.7 ± 0.1 | —2 |
| 12–19 y | 24.7 ± 1.9 | 0.3 ± 0.1 | 4.5 ± 0.7 | —2 |
| 20–39 y | 33.0 ± 1.4 | 1.0 ± 0.1 | 4.5 ± 0.5 | 0.2 ± 0.0 |
| 40–59 y | 26.7 ± 1.2 | 1.0 ± 0.1 | 4.2 ± 0.5 | 0.2 ± 0.1 |
| ≥60 y | 14.4 ± 1.0 | 0.4 ± 0.1 | 2.1 ± 0.3 | 0.1 ± 0.04 |
| Gender | ||||
| Male | 25.8 ± 1.2 | 0.8 ± 0.1 | 3.2 ± 0.3 | 0.1 ± 0.0 |
| Female | 21.9 ± 0.9 | 0.7 ± 0.1 | 3.9 ± 0.3 | 0.1 ± 0.0 |
| Age 15–44 y | 30.1 ± 1.3 | 0.9 ± 0.1 | 5.5 ± 0.5 | —2 |
| Race/ethnicity | ||||
| MA | 26.4 ± 1.1 | 0.7 ± 0.1 | 3.2 ± 0.4 | 0.2 ± 0.13 |
| NHB | 22.6 ± 1.1 | 0.7 ± 0.1 | 2.8 ± 0.3 | 0.1 ± 0.03 |
| NHW | 32.2 ± 1.0 | 1.2 ± 0.2 | 10.3 ± 0.6 | 0.4 ± 0.1 |
| PIR | ||||
| <1.0 | 26.9 ± 1.6 | 1.0 ± 0.2 | 5.2 ± 0.7 | 0.3 ± 0.1 |
| 1.0–1.9 | 25.3 ± 1.2 | 1.0 ± 0.1 | 4.7 ± 0.6 | 0.2 ± 0.13 |
| 2.0–3.9 | 23.6 ± 0.9 | 0.7 ± 0.1 | 3.1 ± 0.3 | 0.1 ± 0.03 |
| ≥4.0 | 19.9 ± 1.6 | 0.5 ± 0.1 | 2.1 ± 0.4 | —2 |
| Supplement use4 | ||||
| Yes | 13.5 ± 1.0 | 0.4 ± 0.1 | 1.5 ± 0.2 | 0.0 ± 0.03 |
| No | 37.2 ± 1.2 | 1.0 ± 0.1 | 5.7 ± 0.5 | 0.2 ± 0.0 |
| Survey period | ||||
| 1999–2000 | NA | 0.8 ± 0.1 | NA | —2 |
| 2001–2002 | NA | 0.6 ± 0.1 | NA | —2 |
| 2003–2004 | NA | 0.8 ± 0.1 | NA | 0.1 ± 0.03 |
| 2005–2006 | NA | 0.8 ± 0.1 | NA | 0.1 ± 0.03 |
| 2007–2008 | NA | 0.5 ± 0.1 | NA | 0.2 ± 0.13 |
| 2009–2010 | NA | 0.8 ± 0.2 | NA | 0.3 ± 0.1 |
Values are percentages ± SE. Serum and RBC folate concentrations were measured by the Bio-Rad radioassay from 1988 to 2006 and assay-adjusted to be comparable to the microbiologic assay, which was used from 2007 to 2010 (13, 16, 17). values are the same as in Table 1. MA, Mexican American; NHB, non-Hispanic black; NHW, non-Hispanic white; NA, not applicable; PIR, poverty-to-income ratio.
Estimate suppressed because the relative SE was ≥40%.
Relative SE was >30% but <40%.
Because information on dietary supplement use is not yet available for 2009–2010, postfortification prevalence estimates were limited to data from 1999 to 2008.