Figure 1: Illustration of the study period. Group A received folic acid fortified bread for 4 wk, underwent an 8-wk washout period, and then received control bread for 4 wk. Group B received control bread for 4 wk, underwent an 8-wk washout period, and then received folic acid fortified bread for 4 wk. Blood analysis was conducted on both groups at the start and end of both 4-wk periods.
  Group A
n=24		 Group B
n=22		 Total
n=46
Age, y 20 (19-21) 20 (19-21) 20 (19-21)
Weight, kg 54.0 (50.0-58.0) 52.6 (48.4-52.6) 52.9 (48.9-58.0)
BMI, kg/m2 21.4 (19.4-22.1) 20.8 (19.6-22.5) 21.1 (19.5-22.1)
Serum tHcy, μmol/L 6.4 (5.4-7.5) 7.1 (6.4-9.0) 6.8 (5.8-7.6)
Serum folate, nmol/L 13.4 (10.1-15.6) 12.8 (9.7-15.5) 13.0 (9.9-15.6)
Serum vitamin B-12, pmol/L 256 (221-335) 245 (210-290) 249 (219-303)
Energy, kJ/d 6161 (5352-7360) 5491 (4629-6729) 5820 (4976-7211)
Protein, g/d 53 (42-67) 47 (39-59) 48 (41-62)
Fat, g/d 52 (37-59) 42 (37-54) 46 (37-57)
Carbohydrate, g/d 201 (180-237) 181 (142-218) 197 (162-223)
Folate, μg/d 250 (194-356) 222 (173-279) 243 (190-296)
Folate, μg/1000 kJ 38 (33-54) 43 (35-50) 41 (34-50)
Vitamin B-12, μg/d 5.0 (2.6-6.4) 3.1 (2.6-4.7) 3.6 (2.6-5.9)
Vitamin B-6, mg/d 1.0 (0.7-1.2) 0.8 (0.6-1.0) 0.9 (0.7-1.1)
Vitamin B-2, mg/d 1.1 (0.8-1.4) 0.9 (0.8-1.2) 1.0 (0.8-1.3)
CES-D scale 10.0 (4.0-12.8) 10.5 (4.0-14.3) 10.5 (4.0-13.0)

All values are medians with 25th-75th percentiles in parentheses. Randomization groups (group A and B) did not differ in baseline characteristics except for serum tHcy (p=0.039).
tHcy, serum total homocysteine; CES-D, Center for Epidemiological Studies-Depression

TABLE 1: Baseline characteristics and dietary intake of the study subjects
  Genotype n Folic acid period Control period p for comparison of treatment1 p for comparison of treatment× genotype1
0 wk 4 wk Change
Δwk 4 - 0		 0 wk 4 wk Change
Δwk 4 - 0
Serum folate, nmol/L All 47 14.2 (10.6–17.5) 23.1 (16.4–27.8)*** 8.6 (4.0–12.9) 14.4 (11.0–17.7) 13.3 (10.4–18.6)* -1.2 (-2.8-1.0) <0.001  
MTHFRC67
7T		 CC 18 14.3 (10.4–21.5) 24.6 (19.1–31.1)** 10.2 (0.5–15.4) 15.5 (11.9–18.0) 16.0 (10.0–18.6) -1.2 (-5.0–1.3) <0.001 0.497
CT 22 14.2 (11.1–16.1) 22.4 (16.4–25.5)** 6.9 (4.5–11.4) 14.4 (11.1–18.2) 13.1 (11.3–19.6) -1.4 (-2.8–1.4)
TT 6 10.5 (8.7–18.5) 18.0 (14.0–24.5)* 5.4 (1.16–12.1) 11.3 (8.9–15.5) 10.0 (7.4–15.2)* -1.2 (-1.5– -0.5)
5-HTT L/L 2 10.3 (6.3–9.2) 20.2 (12.4–17.8) 9.9 (3.2–11.6) 14.7 (9.9–12.2) 11.2 (7.6–9.2) -3.5 (-4.6– -0.7) <0.001 0.512
L/XL 2 17.6 (10.4–16.0) 28.5 (20.2–22.6) 11.0 (4.2–12.2) 21.2 (14.8–17.0) 17.8 (11.2–15.5) -3.4 (-3.6– -1.5)
S/L 18 12.7 (9.7–16.1) 21.9 (15.3–26.3)*** 9.1 (5.0–12.1) 14.2 (10.0–16.06) 12.7 (9.6–16.1) -1.4 (-2.7–1.4)
S/S 23 14.9 (11.1–21.1) 23.3 (16.1–28.3)** 6.8 (-0.2–12.7) 14.3 (10.6–19.9) 13.6 (10.4–19.5) -0.9 (-3.2–1.1)
S/XL 1 12.5 31.5 19.0 17.4 18.3 0.9
DRD4 2/4 9 14.9 (11.6–21.9) 25.1 (22.0–31.8)* 11.1 (8.3–13.9) 17.4 (13.3–25.5) 18.3 (12.0–19.7) -1.4 (-6.6–0.6) <0.001 0.011
2/5 2 20.4 (8.3–22.3) 20.6 (12.1–18.9) 0.2 (-3.4–3.7) 12.1 (7.5–10.7) 15.7 (8.3–15.3) 3.6 (0.8–4.6)
4/4 29 13.8 (10.3–17.0) 22.4 (15.1–25.6)*** 6.1 (1.0–10.8) 14.3 (10.5–16.6) 12.7 (9.6–18.2) -1.1 (-2.8–1.1)
4/4 4 14.6 (9.9–15.1) 28.2 (24.9–29.3) 14.4 (13.0–15.4) 14.9 (11.7–19.0) 13.0 (10.8–16.8) -1.0 (-5.1–1.0)
4/6 1 13.0 12.5 5.7 9.9 13.5 -1.4
4/7 1 11.1 25.4 14.3 14.0 11.3 -2.7
All values are medians with 25th-75th percentiles in parentheses.
1Difference of effects of folic acid treatments and genotypes by repeated-measures ANOVA.
*, **, ***Significantly different from 0 wk: *p<0.05, **p<0.01, ***p<0.001 (Wilcoxon test).
MTHFR, methylenetetrahydrofolate reductase; 5-HTT, serotonin transporter; DRD4, dopamine D4 receptor.
Table 2: Effects of folic acid supplementation on serum folate of subjects with 14 different genotypes
  Genotype n Folic acid period Control period p for comparison of treatment1 p for comparison of treatment× genotype1
0 wk 4 wk Change
Δwk 4 - 0		 0 wk 4 wk Change
Δwk 4 - 0
Serum tHcy, μmol/L All 46 6.6 (5.6–7.5) 5.7 (4.8–6.6)*** −0.8 (-1.2– -0.3) 6.8 (5.3–7.6) 6.6 (5.4–7.3) 0.0 (-0.9–0.5) <0.001  
MTHFR CC 18 6.5 (5.4–7.6)† 5.5 (4.8–6.7)** -0.8 (-1.2–0.0) 6.5 (5.2–7.1) 6.6 (5.4–7.0) 0.0 (-0.6–0.5) <0.001 0.411
CT 22 6.6 (5.7–7.3)† 5.9 (5.1–6.6)** -0.8 (-1.2– -0.3) 6.8 (5.2–7.8) 6.5 (5.4–7.3) 0.0 (-0.7–0.6)
TT 6 6.4 (5.3–8.9) 4.6 (3.8–7.4)* -1.3 (-2.5– -0.4) 7.4 (6.5–10.0) 6.4 (5.6–11.0) -0.8 (-1.3–1.0)
5-HTT L/L 2 7.8 (5.6–6.1) 6.7 (4.9–5.1) -1.1 (-1.0– -0.7) 7.3 (5.3–5.6) 7.5 (5.4–5.8) 0.2 (-0.2–0.5) 0.056 0.792
L/XL 2 5.6 (4.0–4.4) 5.0 (3.5–3.9) -0.6 (-0.8–0.0) 4.9 (3.4–4.0) 5.0 (3.1–1.4) 0.1 (0.0–0.1)
S/L 18 6.9 (5.7–7.6) 5.7 (4.8–6.7)** -0.9 (-1.8– -0.4) 7.0 (6.3–7.8) 6.8 (5.8–7.4) -0.1 (-1.0–0.6)
S/S 23 6.2 (5.4–6.9) 5.5 (4.8–6.3)*** -0.7 (-0.9– -0.3) 6.4 (5.0–7.8) 6.4 (5.4–7.4) 0.0 (-1.2–0.5)
S/XL 1 7.5 7.4 -0.1 6.4 6.6 0.2    
DRD4 2/4 9 6.0 (5.4–7.3) 4.8 (4.7–7.4) -0.7 (-1.0– -0.4) 6.4 (4.2–7.5) 6.5 (4.6–7.5) 0.0 (-0.8–0.9) <0.001 0.051
2/5 2 6.7 (4.9–5.1) 5.7 (4.1–4.4) -1.0 (-1.0– -0.5) 6.3 (4.4–5.1) 6.4 (4.8–4.8) 0.1 (-0.3–0.5)
4/4 29 6.6 (5.7–7.5) 5.8 (5.0–6.6)*** -0.9 (-1.3– -0.2) 6.8 (5.7–7.8) 6.6 (5.4–7.2) 0.0 (-1.0–0.3)
4/5 4 6.2 (5.5–7.8) 5.5 (4.2–6.6) -1.1 (-1.6– -0.5) 7.1 (5.4–7.3) 6.9 (6.0–7.7) 0.4 (-0.7–1.0)
4/6 1 7.7 12.7 -0.5 13.4 11.3 3.6
4/7 1 4.6 4.0 -0.6 5.3 4.1 -1.2
All values are medians with 25th-75th percentiles in parentheses.
1Difference of effects of folic acid treatments and genotypes by repeated-measures ANOVA.
*, **, ***Significantly different from 0 wk: *p<0.05, **p<0.01, ***p<0.001 (Wilcoxon test).
†Significantly different from TT: p<0.05 (Bonferroni multiple comparison).
tHcy, total homocysteine; MTHFR, methylenetetrahydrofolate reductase; 5-HTT, serotonin transporter; DRD4, dopamine D4 receptor.
Table 3: Effects of folic acid supplementation on serum total homocysteine of subjects with 14 different genotype
  Genotype n Folic acid period Control period p for comparison of treatment1 p for comparison of treatment× genotype1
0 wk 4 wk Change
Δwk 4 - 0		 0 wk 4 wk Change
Δwk 4 - 0
CES-D Score All 46 10.0 (3.0–13.0) 5.0 (2.0–10.0)*** -2.0 (-4.0–0.0) 9.0 (4.0–13.3) 8.0 (3.0–11.3) -1.0 (-4.0–2.0) 0.166  
MTHFR CC 18 8.0 (3.8–15.5) 6.0 (1.8–12.5)** -1.5 (-4.0–0.0) 12.0(7.5–15.3) 8.5 (4.5–11.8)* -3.0 (-4.5– -1.5) 0.060 0.067
CT 22 11.0 (2.8–12.3) 5.5 (3.0–8.0) -1.0 (-4.3–2.0) 8.0(1.8–12.0) 8.0 (3.0–11.3) 0.0 (-1.5–2.3)
TT 6 9.0 (1.5–18.8) 4.5 (0.8–8.3)* -3.5 (-10.0– -1.3) 7.0(3.0–15.3) 7.0 (1.8–15.3) -0.5 (-5.0–5.0)
5-HTT L/L 2 10.0 (4.5–10.5) 6.0 (3.8–5.3) -4.0 (-6.8–0.8) 12.0 (9.0–9.0) 10.0 (6.8–8.3) -2.0 (-2.3– -0.8) 0.160 0.805
L/XL 2 14.0 (9.8–11.3) 7.0 (2.3–8.3) -7.0 (-7.5– -3.0) 11.0 (6.8–9.8) 9.5 (6.8–7.5) -1.5 (-2.3–0.0)
S/L 18 9.5 (2.0–12.3) 6.0 (2.8–8.5) -2.0 (-4.3–0.5) 9.5 (4.8–12.5) 8.5 (3.8–14.0) -0.5 (-3.0–3.3)
S/S 23 9.0 (3.0–12.0) 5.0 (1.0–14.0)* -2.0 (-4.0–0.0) 9.0 (1.0–15.0) 7.0 (2.0–11.0) -1.0 (-4.0–1.0)
S/XL 1 5.0 5.0 0.0 8.0 5.0 -3.0
DRD4 2/4 9 5.0 (2.0–14.0) 8.0 (2.0–14.0) 0.0 (-2.5–0.5) 5.0 (2.5–13.5) 8.0 (4.5–13.5) 0.0 (-2.5–4.5) 0.365 0.683
2/5 2 7.0 (1.5–9.0) 8.0 (6.0–6.0) 1.0 (-3.0–4.5) 10.5 (6.8–9.0) 8.0 (6.0–6.0) -2.5 (-3.0– -0.8)
4/4 29 8.0 (2.5–13.0) 5.0 (1.0–9.0)*** -2.0 (-5.0–0.0) 9.0 (4.0–13.0) 7.0 (2.0–11.5)* -2.0 (-4.0–1.0)
4/5 4 11.5 (7.3–15.8) 7.5 (4.8–12.5) -1.5 (-10.8–2.5) 13.5 (12.3–14.8) 10.0 (9.0–17.0) -3.5 (-4.0–3.0)
4/6 1 11.0 6.0 -5.0 5.0 10.0 5.0
4/7 1 13.0 16.0 3.0 20.0 22.0 2.0
All values are medians with 25th-75th percentiles in parentheses.
1Difference of effects of folic acid treatments and genotypes by repeated-measures ANOVA.
*, **, ***Significantly different from 0 wk: *p<0.05, **p<0.01, ***p<0.001.
CES-D, Center for Epidemiological Studies-Depression; MTHFR, methylenetetrahydrofolate reductase; 5-HTT, serotonin transporter; DRD4, dopamine D4 receptor
Table 4: Effects of folic acid supplementation on CES-D score of subjects with 14 different genotypes
  Folic acid period Control period p for comparison of treatment1 p for comparison of score1
n 0 wk 4 wk Change
Δ wk 4 - 0		 n 0 wk 4 wk Change
Δ wk 4 - 0		    
Serum folate, nmol/L <16 of CES-D score 39 13.4 (10.6–17.4) 22.4 (16.1–26.0)*** 7.0 (3.2–11.8) 38 14.4 (11.1–18.2) 13.3 (10.4–18.6)* -1.4 (-2.9–1.0) <0.001 0.801
≥16 of CES-D score 7 15.4 (14.3–17.7) 28.1 (21.5–31.0)* 12.7 (10.9–14.5) 8 14.4 (10.1–17.1) 14.0 (9.3–18.9) -1.0 (-2.4–2.1)
Serum tHcy, μmol/L <16 of CES-D score 39 6.6 (5.4–7.5) 5.8 (4.8–6.6)*** -0.8 (-1.2– -0.2) 38 6.8 (5.7–7.6) 6.6 (5.5–7.3) 0.0 (-0.9–0.6) <0.001 0.586
≥16 of CES-D score 7 6.0 (5.6–7.1) 5.6 (4.2–6.6)* -0.9 (-1.5– -0.3) 8 5.9 (5.0–8.9) 6.1 (4.3–8.0) -0.1 (-1.0–0.2)
CES-D score <16 of CES-D score 39 7.0 (2.0–12.0) 5.0 (1.0–8.0)** -2.0 (-4.0–0.0) 38 8.0 (3.8–12.0) 7.0 (2.8–9.3) -1.0 (-3.3–1.3) 0.088 0.007
≥16 of CES-D score 7 20.0 (17.0–23.0) 17.0 (15.0–19.0) -3.0 (-9.0–0.0) 8 19.5 (17.3–27.5) 19.0 (14.0–23.8) -1.5 (-4.8–2.8)
Energy intake, kJ/d <16 of CES-D score 39 6158 (5135–7237) 6309 (4909–7435) 152 (-726–1064) 38 5769 (5071–6965) 6174 (4946–7049) 212 (-619–766) 0.674 0.012
≥16 of CES-D score 7 5781 (3194-5877) 6071 (3617-6504) 423 (-1002–723) 8 4797 (6223–7038) 5652 (4450–6801) -3 (-39–46)
Folate, μg/d <16 of CES-D score 39 255 (194–355) 274 (201–335) 14 (-42–57) 38 229 (184–329) 249 (172–361) 16 (-27–67) 0.405 0.471
≥16 of CES-D score 7 184 (139–233) 229 (149–271) 10 (-10–62) 8 206 (172–252) 200 (153–333) -3(-39-46)
All values are medians with 25th-75th percentiles in parentheses.
1Difference of effects of folic acid treatments and CES-D score (<16 and ≥16) by ANOVA.
*, **, ***Significantly different from 0 wk: *p<0.05, **p<0.01, ***p<0.001.
tHcy, total homocysteine; CES-D, Center for Epidemiological Studies-Depression.
Table 5: Effects of folic acid supplementation on serum folate, serum total homocysteine and CES-D scores of subjects without depressive symptoms
(CES-D score ≥16) and subjects without depressive symptoms (CES-D score <16).