TABLE 2.
Mean concentrations of blood biomarkers throughout the year and by season1
| Biomarkers | 12-mo intake2 | Cutoff for adequacy (prevalence of adequacy)3 | Rainy season intake (hungry: July–September)2 | Dry season intake (harvest: February–April)2 | Difference between seasons | CCV (95% CI)4 |
| % | % | |||||
| Folate (nmol/L) | 14.9 (6.6, 33.4) | >10 (82.3)5 | 13.4 (12.2, 14.9) | 12.5 (11.4, 13.9) | 6.7 | 23.8 (20.5, 26.5) |
| Riboflavin (EGRAC coefficient)6 | 2.4 (1.5, 3.7) | <1.37 (0.7) | 2.3 (2.1, 2.4) | 2.6 (2.5, 2.7) | −14.16 | 9.0 (7.6, 10.4) |
| Vitamin B-12 (pmol/L) | 342.3 (139.1, 842.2) | >2208 (80.7) | 333.7 (285.9, 389.6) | 353.1 (302.5, 412.1) | −5.8 | 3.5 (1.9, 5.1) |
| Active vitamin B-12 (pmol/L) | 70.9 (20.0, 251.5) | >379 (85.8) | 67.2 (55.9, 80.8) | 76.3 (63.5, 91.7) | −13.5 | 6.2 (3.7, 8.8) |
| Choline (μmol/L) | 8.2 (4.7, 14.0) | >1010 (20.9) | 8.2 (7.6, 8.8) | 8.3 (7.7, 8.9) | −1.3 | 11.1 (8.9, 13.4) |
| Betaine (μmol/L) | 40.4 (20.9, 78.4) | —11 | 45.7 (41.7, 50.1) | 36.5 (33.3, 39.9) | 20.1 | 9.8 (7.6, 12.0) |
| DMG (μmol/L) | 3.3 (1.1, 9.3) | — | 2.9 (2.5, 3.4) | 3.4 (2.9, 4.0) | −18.4 | 16.3 (13.4, 19.3) |
| DMG/betaine | 0.08 (0.03, 0.26) | — | 0.06 (0.05, 0.07) | 0.09 (0.08, 0.11) | −49.0 | 23.3 (20.6, 25.9) |
| Methionine (μmol/L) | 29.1 (19.6, 43.3) | — | 28.9 (27.3, 30.7) | 29.4 (27.7, 31.1) | −1.5 | 3.9 (2.0, 5.8) |
| SAM (nmol/L) | 90.3 (59.1, 137.8) | — | 90.3 (85.3, 95.5) | 86.3 (81.6, 91.2) | 4.4 | 4.6 (3.0, 6.1) |
| SAH (nmol/L) | 12.2 (6.8, 21.9) | — | 11.1 (10.5, 11.9) | 12.9 (12.1, 13.7) | −15.9 | 7.8 (4.7, 10.9) |
| SAM:SAH | 7.42 (3.8, 14.5) | — | 8.1 (7.6, 8.7) | 6.7 (6.2, 7.2) | 17.6 | 9.4 (5.8, 12.9) |
| Homocysteine (μmol/L) | 8.03 (4.2, 15.3) | <1512 (98.8) | 7.9 (7.2, 8.7) | 8.1 (7.4, 9.0) | −2.9 | 10.2 (7.9, 12.5) |
| Vitamin B-6 (nmol/L) | 39.7 (14.3, 110.6) | — | 33.8 (29.8, 38.2) | 36.0 (31.8, 40.7) | −6.6 | 26.2 (22.4, 30.0) |
| Cysteine (μmol/L) | 224.9 (170.8, 296.1) | — | 217.1 (207.9, 226.7) | 219.0 (209.9, 228.6) | −0.9 | 4.1 (3.0, 5.2) |
n = 316 (293 for riboflavin). CCV, coefficient of cyclic variation; DMG, dimethylglicine; EGRAC, erythrocyte glutathione reductase activation coefficient; SAH, S-adenosylhomocysteine; SAM, S-adenosylmethionine.
Values are geometric means; 95% CIs in parentheses (geometric mean ± 2 SD).
Percentages of the observations beyond the cutoff in parentheses.
Calculated as the square root of half the sum of the squared coefficients of the Fourier terms.
From reference 27.
For the riboflavin assay, higher EGRAC values reflect higher riboflavin deficiency.
From reference 28.
From reference 29.
From reference 30.
From reference 26.
Indicates that no suitable cutoff could be identified.
From reference 31.