Table 2.
Multivariable-adjusted HRs and 95% CIs of incident obesity by quintiles of magnesium intake levels: the CARDIA study, 1985–86 to 2015–16a–e
| Quintiles of Mg intake levels (mg/1,000 kcal) | P for trend | |||||
|---|---|---|---|---|---|---|
| Q1 (lowest) | Q2 | Q3 | Q4 | Q5 (highest) | ||
| All participants (n = 4,097) | ||||||
| Range (mg/1,000 kcal) | <111.49 | 111.49–132.39 | 132.39–154.33 | 154.33–184.73 | ≥184.73 | NA |
| No. of cases/participants | 408/819 | 385/820 | 342/819 | 295/820 | 245/819 | NA |
| Model 1 | 1 (Ref.) | 0.88 (0.77, 1.02) | 0.76(0.65, 0.88) | 0.58 (0.49, 0.68) | 0.45 (0.38, 0.54) | <0.01 |
| Model 2 | 1 (Ref.) | 0.83 (0.72, 0.96) | 0.81 (0.70, 0.95) | 0.53 (0.44, 0.63) | 0.45 (0.37, 0.55) | <0.01 |
| Model 3 | 1 (Ref.) | 0.86(0.74, 1.00) | 0.83 (0.71, 0.97) | 0.55 (0.46, 0.66) | 0.49 (0.40, 0.60) | <0.01 |
| Mg supplementation non-users (n = 2,456) | ||||||
| Range (mg/1,000 kcal) | <105.00 | 105.00–120.86 | 120.86–139.31 | 139.31–162.11 | ≥162.11 | NA |
| No. of cases/participants | 234/491 | 220/491 | 212/492 | 191/491 | 173/491 | NA |
| Model 3 | 1 (Ref.) | 0.93 (0.76, 1.12) | 0.79(0.65, 0.96) | 0.76(0.61, 0.94) | 0.61 (0.48, 0.78) | <0.01 |
| Mg supplementation users (n = 1,641) | ||||||
| Range (mg/1,000 kcal) | <133.17 | 133.17–155.74 | 155.74–179.02 | 179.02–209.14 | ≥209.14 | NA |
| No. of cases/participants | 192/328 | 141/328 | 118/329 | 93/328 | 101/328 | NA |
| Model 3 | 1 (Ref.) | 0.79(0.63, 1.00) | 0.48 (0.37, 0.62) | 0.41 (0.31, 0.54) | 0.49 (0.36, 0.66) | <0.01 |
Abbreviations: BMI, body mass index; CARDIA, Coronary Artery Risk Development in Young Adults; CI, confidence interval; HR, hazard ratio; Mg, magnesium; Q, quintile; Ref., reference.
All models were constructed using Cox proportional hazards regression model. P for trend was examined using the medians of Mg quintiles. The values of covariates, if not specified, were calculated as the cumulative averages of repeated measurements by incident obesity or last follow-up.
Model 1 was adjusted for age at Y0 (continuous), sex (female or male), race (blacks or whites), and study center.
Model 2 was additionally adjusted for education (<12.0, 12.0, 15.9, or ≥16.0, year), smoking status (never, past, or current), alcohol consumption (never, 0.1, 11.9, 12.0, 23.9, or ≥24 ml/day), physical activity (quintiles), total energy intake (quintiles), Mg supplementation use (yes or no) and BMI at Y0 (continuous).
Model 3 was additionally adjusted for systolic blood pressure (quintiles), total cholesterol (quintiles), HDL/LDL-cholesterol ratio (quintiles), triglycerides (quintiles), fasting glucose (quintiles), and medical histories of diabetes and hypertension (yes or no).
In stratified analyses, Mg intake quintiles were calculated separately for each subgroup (Mg supplementation non-users and users).