Table 3.
Mediation of change in behavioral determinants between intervention and dietary behavior change (18 months, n = 240)
| T0–T2 Fruit intake (g/day) | X -- > Y (c path) a,h | ||||||||
| B(SE) | 95%-CI | ||||||||
| Crude analysis | 32.3 (13.2) | 6.3; 58.4 | |||||||
| X -- > Y (c’ path) direct b,h | X -- > M (a path) c,h | M -- > Y (b path) d,h | Indirect effect (a*b) e,g | Proportion mediated f | |||||
| B (SE) | 95%-CI | B (SE) | 95%-CI | B (SE) | 95%-CI | B (SE) | 95%-CI | B (SE) | |
| Intention | 20.3 (12.6) | −4.5; 45.2 | 0.4 (0.2) | 0.1; 0.7 | 26.7 (5.0) | 16.8; 36.5 | 10.9 (5.1) | 2.9; 23.6 | 0.35 |
| Attitude | 16.0 (12.7) | −9.1; 41.1 | 0.6 (0.1) | 0.1; 0.6 | 33.6 (6.7) | 20.4; 46.7 | 11.9 (4.5) | 4.7; 22.8 | 0.43 |
| Social influence | 29.4 (13.3) | 3.2; 55.6 | 0.2 (0.1) | −0.1; 0.5 | 10.8 (6.0) | −1.0; 22.7 | 2.2 (2.1) | −0.4; 9.0 | - |
| Self-efficacy | 21.0 (12.4) | −3.5; 45.5 | 0.3 (0.1) | 0.1; 0.6 | 34.7 (5.8) | 23.3; 46.2 | 11.0 (5.3) | 1.3; 22.7 | 0.35 |
| Motivation | 15.0 (11.7) | −8.0; 38.0 | 0.5 (0.2) | 0.1; 0.9 | 31.3 (3.6) | 24.1; 38.5 | 15.9 (6.6) | 3.4; 29.1 | 0.51 |
| Action control | 11.4 (11.8) | −11.8; 34.6 | 0.4 (0.2) | 0.2; 0.7 | 43.0 (5.2) | 32.7; 53.3 | 19.0 (6.9) | 6.3; 33.8 | 0.63 |
| Dietary skills | 28.2 (13.5) | 1.6; 54.8 | 0.3 (0.1) | 0.1; 0.5 | 15.3 (8.4) | −1.3; 31.9 | 3.9 (2.7) | 0.3; 11.5 | 0.12 |
| Psychological profile | 11.1 (12.2) | −13.0; 35.2 | 2.5 (0.8) | 1.0; 4.1 | 7.0 (1.0) | 5.0; 9.0 | 17.7 (5.8) | 6.7; 29.7 | 0.62 |
| T0–T2 Fiber intake from bread (%) | X -- > Y (c path) a, h | ||||||||
| B(SE) | 95%-CI | ||||||||
| Crude analysis | 0.3 (0.2) | 0.0; 0.6 | |||||||
| X -- > Y (c’ path) direct b,h | X -- > M (a path) c,h | M -- > Y (b path) d,h | Indirect effect (a*b) e,g | Proportion mediated f | |||||
| B (SE) | 95%-CI | B (SE) | 95%-CI | B (SE) | B (SE) | 95%-CI | B (SE) | ||
| Intention | 0.3 (0.2) | 0.0; 0.6 | 0.4 (0.2) | −0.1; 0.8 | 0.0 (0.0) | −0.1; 0.1 | 0.0 (0.0) | −0.1; 0.0 | - |
| Attitude | 0.3 (0.2) | 0.0; 0.6 | 0.0 (0.2) | −0.3; 0.3 | 0.1 (0.1) | −0.1; 0.2 | 0.0 (0.0) | 0.0; 0.0 | - |
| Social influence | 0.3 (0.2) | 0.0; 0.6 | 0.1 (0.2) | −0.2; 0.4 | −0.1 (0.1) | −0.2; 0.1 | 0.0 (0.0) | −0.1; 0.0 | - |
| Self-efficacy | 0.3 (0.2) | 0.0; 0.6 | 0.1 (0.2) | −0.2; 0.4 | 0.0 (0.1) | −0.1; 0.2 | 0.0 (0.0) | 0.0; 0.0 | - |
| Motivation | 0.3 (0.2) | 0.0; 0.6 | 0.0 (0.2) | −0.3; 0.4 | −0.1 (0.1) | −0.2; 0.0 | 0.0 (0.0) | −0.1; 0.0 | - |
| Action control | 0.3 (0.2) | 0.0; 0.6 | 0.2 (0.1) | −0.1; 0.4 | 0.1 (0.1) | 0.0; 0.3 | 0.0 (0.0) | 0.0; 0.1 | - |
| Dietary skills | 0.3 (0.2) | 0.0; 0.6 | 0.3 (0.1) | 0.1; 0.5 | 0.1 (0.1) | −0.1; 0.3 | 0.0 (0.0) | 0.0; 0.1 | - |
| Psychological profile | 0.3 (0.2) | 0.0; 0.6 | 0.9 (0.8) | −0.6; 2.4 | 0.0 (0.0) | 0.0; 0.0 | 0.0 (0.03) | 0.0; 0.1 | - |
| T0–T2 Fat intake from bread spread (%) | X -- > Y (c path) a,h | ||||||||
| B(SE) | 95%-CI | ||||||||
| Crude analysis | −2.6 (0.8) | −4.2; −1.1 | |||||||
| X -- > Y (c’ path) direct b,h | X -- > M (a path) c,h | M -- > Y (b path) d,h | Indirect effect (a*b) e,g | Proportion mediated f | |||||
| B (SE) | 95%-CI | B (SE) | 95%-CI | B (SE) | 95%-CI | B (SE) | 95%-CI g | (a*b)/c | |
| Intention | −2.4 (0.8) | −4.0; −0.9 | 0.3 (0.2) | 0.0; 0.7 | −0.6 (0.3) | −1.2; 0.0 | −0.2 (0.1) | −0.6; 0.0 | - |
| Attitude | −2.6 (0.8) | −4.1; −1.1 | 0.1 (0.1) | −0.1; 0.4 | −0.8 (0.4) | −1.6; 0.0 | −0.1 (0.1) | −0.5; 0.1 | - |
| Social influence | −2.6 (0.8) | −4.1; −1.0 | 0.4 (0.2) | 0.1; 0.7 | −0.5 (0.3) | −1.2; 0.2 | −0.2 (0.1) | −0.6; 0.0 | - |
| Self-efficacy | −2.5 (0.8) | −4.0; −1.0 | 0.1 (0.1) | −0.2; 0.4 | −1.0 (0.4) | −1.7; −0.2 | −0.1 (0.2) | −0.5; 0.2 | - |
| Motivation | −2.5 (0.8) | −4.0; −1.0 | 0.2 (0.2) | −0.2; 0.5 | −0.9 (0.3) | −1.5; −0.3 | −0.2 (0.2) | −0.7; 0.1 | - |
| Action control | −2.2 (0.8) | −3.7; −0.7 | 0.3 (0.1) | 0.1; 0.6 | −1.2 (0.4) | −1.9; −0.5 | −0.4 (0.2) | −1.0; −0.1 | 0.15 |
| Dietary skills | −2.5 (0.8) | −4.0; −1.0 | 0.3 (0.1) | 0.1; 0.5 | −0.2 (0.5) | −1.2; 0.8 | −0.1 (0.2) | −0.5; 0.2 | - |
| Psychological profile | −2.2 (0.8) | −3.7; −0.7 | 1.7 (0.7) | 0.3; 3.1 | −0.2 (0.1) | −0.4; −0.1 | −0.4 (0.2) | −1.0; −0.1 | 0.15 |
aC path (total effect): the association between intervention and dietary behaviors (fruit intake, fiber intake from bread, fat intake from bread spread). All analyses are adjusted for baseline value, sex, and recruitment phase
bC’ path (direct effect): the association between intervention and dietary behaviors, additionally adjusted for mediator (behavioral determinants)
cA path: association between intervention and behavioral determinant
dB path: association between behavioral determinant and dietary behavior
eIndirect effect (a*b): the indirect effect of the intervention on dietary behavior through behavioral determinant
fProportion effect mediated ((a*b)/c): the proportion of the total effect that was mediated through behavioral determinant
gStandard error and confidence interval for indirect effects were calculated with bootstrapping (5000 samples)
hAll analyses used linear regression models