TABLE 1.
Characteristics of participants by vitamin B-12 and UMFA status1
| Low vitamin B-12 status | Normal vitamin B-12 status | |||
|---|---|---|---|---|
| Characteristics | UMFA ≤ 1 nmol/L (n = 217) | UMFA > 1 nmol/L (n = 152) | UMFA ≤ 1 nmol/L (n = 1269) | UMFA > 1 nmol/L (n = 782) |
| Women, % | 48.7 ± 4.9 | 64.9 ± 4.4 | 50.1 ± 2.2 | 57.7 ± 2.1 |
| Age, y | 69.3 ± 0.6 | 72.2 ± 0.8 | 67.7 ± 0.2 | 69.6 ± 0.5 |
| Race/Hispanic origin, % | ||||
| Non-Hispanic white | 83.6 ± 3.4 | 89.1 ± 2.2 | 77.1 ± 2.3 | 83.8 ± 2.2 |
| Non-Hispanic Black | 5.3 ± 1.6 | 4.4 ± 1.1 | 8.5 ± 1.2 | 8.2 ± 1.6 |
| Non-Hispanic Asian | 2.7 ± 0.8 | 1.4 ± 0.5 | 4.6 ± 0.7 | 2.6 ± 0.6 |
| Hispanic | 8.4 ± 2.1 | 5.1 ± 1.5 | 9.8 ± 1.5 | 5.4 ± 1.2 |
| Education, % | ||||
| <High school | 20.7 ± 3.9 | 17.1 ± 2.7 | 16.2 ± 1.8 | 13.1 ± 1.9 |
| High school graduate or general equivalency diploma | 23.7 ± 4.5 | 23.4 ± 4.1 | 20.7 ± 2.2 | 21.5 ± 2.0 |
| Some college or associate degree | 32.4 ± 4.8 | 40.0 ± 5.6 | 29.7 ± 2.2 | 33.0 ± 2.3 |
| ≥Bachelor's degree | 23.2 ± 4.0 | 19.5 ± 3.8 | 33.4 ± 2.9 | 32.4 ± 2.8 |
| Smoking,2 % | 17.5 ± 3.3a | 7.0 ± 2.1b | 12.9 ± 1.2a | 7.7 ± 1.2b |
| Heavy drinking,2 % | 15.1 ± 3.7 | 5.4 ± 2.9 | 11.5 ± 1.6 | 8.3 ± 1.2 |
| Folic acid DS use,2 % | 19.4 ± 3.7a | 43.8 ± 5.3b | 29.1 ± 1.5a,b | 60.9 ± 2.4c |
| Vitamin B-12 DS use,2 % | 21.4 ± 4.3a | 43.0 ± 5.6b | 33.5 ± 1.7b | 64.5 ± 2.3c |
| Medication use,2,3 % | 28.2 ± 3.4 | 37.9 ± 6.1 | 28.8 ± 1.7 | 34.8 ± 2.2 |
| Folate intake,2 DFE/d | 633.5 ± 65.6a | 873.6 ± 43.8b | 686.7 ± 26.3a | 1064.6 ± 35.2c |
| <EAR,2 % | 20.0 ± 2.4a | 5.0 ± 2.2b | 14.0 ± 1.8a | 3.0 ± 1.0b |
| >UL,2 % | 0.6 ± 0.5a | 2.0 ± 0.8a | 0.8 ± 0.3a | 6.0 ± 0.9b |
| Vitamin B-12 intake,2 µg/d | 21.1 ± 7.3a | 36.7 ± 13.6a | 87.1 ± 9.6b | 197.4 ± 38.7c |
| <EAR,2 % | 4.0 ± 3.4 | 2.0 ± 2.0 | 3.0 ± 1.0 | 1.0 ± 0.4 |
Values are means ± SEs. Low serum vitamin B-12 status is defined as either serum vitamin B-12 < 150 pmol/L or methylmalonic acid > 271 nmol/L. The 75th percentile of UMFA from a previous NHANES analysis was used as a cutoff (26). DFE, dietary folate equivalent; DS, dietary supplement; EAR, estimated average requirement; UL, tolerable upper intake level; UMFA, unmetabolized folic acid.
Values in a row with different superscript letters are significantly different based on multiple t tests, P < 0.0125. Any nonnormal variables were log transformed before statistical comparison. Demographic data (i.e., sex, age, race/Hispanic origin, and education) were not statistically compared.
Use of metformin, proton inhibitor, or H2 antagonist that may inhibit vitamin B-12 absorption.