Table 1.
Baseline characteristics of CARDIA study participants according to total magnesium intake quintiles
| Characteristics | Quintile 1 | Quintile 2 | Quintile 3 | Quintile 4 | Quintile 5 | P values* |
|---|---|---|---|---|---|---|
| n | 899 | 900 | 899 | 900 | 899 | |
| Magnesium intake (mg/1,000 kcal) | 99.9 (91.7–106.1) | 121.0 (116.5–125.2) | 140.1 (134.8–145.5) | 162.1 (155.8–169.3) | 201.5 (187.7–233.3) | — |
| Age (years) | 23.9 ± 3.8 | 24.3 ± 3.7 | 25.0 ± 3.6 | 25.5 ± 3.4 | 26.0 ± 3.2 | <0.01 |
| Female sex (%) | 52.4 | 46.8 | 46.8 | 53.0 | 64.7 | <0.01 |
| African American (%) | 82.7 | 67.7 | 48.5 | 31.1 | 23.0 | <0.01 |
| Education (years) | 12.8 ± 1.8 | 13.3 ± 2.1 | 13.9 ± 2.1 | 14.4 ± 2.3 | 14.8 ± 2.3 | <0.01 |
| Current smoker (%) | 36.4 | 33.0 | 28.1 | 27.2 | 24.7 | <0.01 |
| Alcohol intake (g/day) | 10.2 ± 20.1 | 12.9 ± 22.2 | 12.2 ± 19.6 | 13.4 ± 22.6 | 10.6 ± 16.2 | <0.01 |
| Physical activity score (units) | 354.0 ± 293.5 | 407.7 ± 305.2 | 421.4 ± 289.5 | 435.7 ± 289.3 | 474.8 ± 288.5 | <0.01 |
| Family history of diabetes (%) | 16.2 | 14.0 | 14.6 | 12.3 | 11.4 | 0.02 |
| BMI (kg/m2) | 25.0 ± 5.9 | 25.0 ± 5.5 | 24.5 ± 4.7 | 24.1 ± 4.4 | 24.0 ± 4.3 | <0.01 |
| Waist circumference (cm) | 78.5 ± 12.9 | 79.1 ± 11.7 | 78.4 ± 10.6 | 77.3 ± 10.7 | 76.2 ± 10.0 | <0.01 |
| Glucose (mg/dl) | 81.3 ± 8.8 | 81.9 ± 9.0 | 81.6 ± 8.5 | 82.2 ± 7.7 | 82.0 ± 7.4 | 0.29 |
| Insulin (μU/ml) | 12.8 ± 6.9 | 12.5 ± 6.5 | 11.2 ± 4.9 | 10.6 ± 4.7 | 10.5 ± 4.8 | <0.01 |
| Systolic blood pressure (mmHg) | 111.2 ± 10.8 | 111.5 ± 11.2 | 110.8 ± 10.9 | 109.9 ± 10.2 | 109.2 ± 11.3 | <0.01 |
| Diastolic blood pressure (mmHg) | 68.2 ± 10.2 | 68.8 ± 10.2 | 69.2 ± 9.5 | 68.8 ± 9.0 | 68.2 ± 9.3 | 0.11 |
| Total energy intake (kcal) | 3,264 ± 1,650 | 3,170 ± 1,571 | 2,943 ± 1,363 | 2,652 ± 1,189 | 2,374 ± 1,127 | <0.01 |
| Total saturated fat (g) | 53.4 ± 31.3 | 51.6 ± 28.3 | 47.8 ± 25.0 | 42.3 ± 21.6 | 35.2 ± 20.6 | <0.01 |
| Crude fiber (g) | 4.7 ± 2.9 | 5.4 ± 3.0 | 5.6 ± 3.1 | 6.0 ± 3.2 | 6.7 ± 4.0 | <0.01 |
| Whole grain (times/week) | 4.9 ± 7.3 | 7.4 ± 8.6 | 9.7 ± 9.7 | 11.0 ± 9.5 | 13.1 ± 11.1 | <0.01 |
| Magnesium supplementation (mg) | 1.6 ± 9.4 | 4.0 ± 15.7 | 9.5 ± 25.2 | 17.9 ± 35.9 | 69.4 ± 137.1 | <0.01 |
Data are median (interquartile range), means ± SD, or %.
*P values are for any difference across the quintiles of magnesium intake using ANOVA, Kruskal-Wallis test, or χ2 test as appropriate.