Table 1.
Folate and B12 status before and after folate supplementation
| Supplementation | Circulating
vitamin levels, ng/ml
|
||
|---|---|---|---|
| Plasma folate (n) | Erythrocyte folate (n) | Plasma B12 (n) | |
| Folate-deficient individuals | |||
| Before | 4.3 ± 0.8 (7) | 95.1 ± 9.7 (10) | 0.33 ± 0.07 (8) |
| After | 53.6 ± 9.8** (5) | 486.4 ± 79.3** (5) | 0.40 ± 0.12 (4) |
| Normal individuals | |||
| Before | 11.9 ± 1.3† (16) | 277.6 ± 30.6†† (16) | 0.56 ± 0.07 (16) |
| After | 67.4 ± 7.9** (15) | 457.6 ± 45.0* (15) | 0.52 ± 0.04 (15) |
Work with human tissues was approved by the Committee for the Protection of Human Subjects at the University of California, Berkeley. Folate and B12 levels were determined by competitive radiobinding assay (Bio-Rad). Individuals with erythrocyte folate levels of <140 ng/ml were classified as folate-deficient. Postsupplementation values are the average of values determined 6, 7, and 8 weeks after initiation of daily consumption of 5 mg of folic acid. Individuals with normal levels of folate had higher plasma B12 levels than did the folate deficient group (P = 0.051). Values are expressed as the mean ± SEM of the arithmetic data. Values significantly elevated in the postsupplementation groups compared with values in the presupplementation group are indicated by ∗ (P < 0.005) and ∗∗ (P < 0.0001). Values significantly elevated in normal individuals compared with values in folate-deficient individuals before supplementation are indicated by † (P < 0.001) and †† (P < 0.0001).