TABLE 5.
Prevalence of UMFA concentrations >1 nmol/L by variable categories in US participants ≥1 y of age, NHANES 2007–20081
| Fasting and nonfasting participants ≥1 y |
Fasting (≥8 h) adults (≥20 y) |
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| Variables | Sample size, n | Prevalence, % | Sample size, n | Prevalence, % |
| All | 2676 | 33.2 (29.7, 36.9) | 823 | 21.0 (17.7, 24.7) |
| Age, y | ||||
| 1–5 | 263 | 41.2 (33.7, 49.1) | — | — |
| 6–11 | 337 | 44.8 (36.3, 53.6) | — | — |
| 12–19 | 337 | 33.7 (26.4, 41.9) | — | — |
| 20–39 | 536 | 22.7 (19.2, 26.6) | 255 | 13.9 (9.1, 20.7) |
| 40–59 | 560 | 29.0 (23.3, 35.4) | 268 | 17.6 (13.5, 22.7) |
| ≥60 | 643 | 48.3 (42.7, 54.0) | 300 | 36.2 (29.8, 43.1) |
| P value | <0.0001 | 0.0001 | ||
| Sex | ||||
| Male | 1378 | 30.1 (25.4, 35.3) | 411 | 16.3 (11.4, 22.8) |
| Female | 1298 | 36.3 (32.5, 40.2) | 412 | 25.3 (21.2, 30.0) |
| P value | 0.0277 | 0.0177 | ||
| Race-ethnicity2 | ||||
| All Hispanic | 875 | 25.7 (22.0, 29.8) | 245 | 10.9 (7.0, 16.6) |
| NHB | 563 | 35.8 (28.4, 44.0) | 162 | 26.0 (17.6, 36.6) |
| NHW | 1121 | 34.7 (30.5, 39.1) | 391 | 22.6 (18.1, 27.9) |
| P value | 0.0040 | 0.0159 | ||
| Fasting time, h | ||||
| <3 | 1047 | 41.9 (36.8, 47.1) | — | — |
| 3 to <8 | 573 | 41.7 (35.8, 47.8) | — | — |
| ≥8 | 1056 | 21.5 (18.2, 25.3) | — | — |
| P value | <0.0001 | — | ||
| Folic acid–containing supplement3 | ||||
| Yes | 688 | 51.1 (47.8, 54.3) | 241 | 35.2 (28.0, 43.2) |
| No | 1857 | 24.9 (20.8, 29.6) | 523 | 12.9 (8.9, 18.3) |
| P value | <0.0001 | 0.0001 | ||
| Total folic acid intake,4 μg/d | ||||
| <100 | 596 | 18.3 (14.0, 23.6) | 209 | 8.2 (4.1, 15.6)* |
| 100 to <200 | 609 | 22.4 (17.5, 28.1) | 168 | 12.5 (7.4, 20.4) |
| 200 to <400 | 614 | 31.2 (27.3, 35.4) | 157 | 15.0 (9.9, 22.0) |
| ≥400 | 630 | 54.9 (50.1, 59.6) | 214 | 38.7 (31.6, 46.3) |
| P value | <0.0001 | 0.0001 | ||
| Alcohol intake,5 drinks/d | ||||
| No drinks | — | — | 253 | 24.0 (19.2, 29.5) |
| <1 | — | — | 404 | 21.1 (15.7, 27.8) |
| 1 to <2 | — | — | 71 | 19.8 (11.6, 31.6) |
| ≥2 | — | — | 39 | 8.2 (2.0, 28.5)** |
| P value | — | 0.0403 | ||
| Smoking status6 | ||||
| Nonsmoker | 2029 | 36.4 (32.6, 40.3) | 615 | 24.2 (20.7, 28.1) |
| Smoker | 487 | 21.2 (16.0, 27.6) | 207 | 11.7 (6.3, 20.9) |
| P value | 0.0009 | 0.0131 | ||
| Body surface area,7 m2 | ||||
| <1.5 | 612 | 42.8 (37.6, 48.2) | 22 | 17.2 (4.5, 47.7)** |
| 1.5 to <1.8 | 686 | 35.0 (29.0, 41.6) | 238 | 26.4 (19.4, 34.9) |
| 1.8 to <2.0 | 578 | 35.2 (28.7, 42.3) | 229 | 21.2 (14.7, 29.7) |
| ≥2 | 685 | 25.4 (21.1, 30.2) | 316 | 16.0 (11.7, 21.5) |
| P value | 0.0005 | 0.06 | ||
| RBC folate,8 nmol/L | ||||
| <800 | 504 | 16.3 (10.4, 24.6) | 167 | 9.1 (5.2, 15.4) |
| 800 to <1200 | 1051 | 26.5 (22.4, 31.1) | 278 | 11.9 (7.0, 19.5) |
| 1200 to <1500 | 555 | 34.5 (28.6, 41.0) | 141 | 20.3 (10.8, 34.7) |
| ≥1500 | 557 | 53.4 (48.2, 58.4) | 234 | 37.3 (30.2, 44.9) |
| P value | <0.0001 | <0.0001 | ||
Values are percentages (95% CIs). Pregnant and lactating women were excluded; otherwise pairwise deletion was used for missing data. Fasting adults did not consume any food or supplements for ≥8 h before blood draw. *30% > RSE ≤ 40%; **RSE >40%; all other values had an RSE ≤30%. NHB, non-Hispanic black; NHW, non-Hispanic white; RSE, relative standard error; UMFA, unmetabolized folic acid.
All Hispanic subgroup represents the sum of Mexican American (not shown) and other Hispanic (not shown) ethnicity.
Use of folic acid–containing supplement during the last 30 d.
From folic acid–containing supplement use during the last 30 d and from dietary folic acid intake from first 24-h dietary recall.
Calculated as the mean daily number of “standard” drinks [(quantity × frequency)/365.25]; 1 drink ∼15-g ethanol; only available for persons ≥20 y of age.
“Smoker” defined by a serum cotinine concentration >10 μg/L.
Calculated as the square root of [(height in cm × weight in kg)/3600] or the square root of [(height in inches × weight in pounds)/3131].
RBC folate was measured by microbiologic assay.