Table 1

Baseline characteristics of CARDIA study participants according to total magnesium intake quintiles

CharacteristicsQuintile 1Quintile 2Quintile 3Quintile 4Quintile 5P values*
n899900899900899
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 ± 3.824.3 ± 3.725.0 ± 3.625.5 ± 3.426.0 ± 3.2<0.01
Female sex (%)52.446.846.853.064.7<0.01
African American (%)82.767.748.531.123.0<0.01
Education (years)12.8 ± 1.813.3 ± 2.113.9 ± 2.114.4 ± 2.314.8 ± 2.3<0.01
Current smoker (%)36.433.028.127.224.7<0.01
Alcohol intake (g/day)10.2 ± 20.112.9 ± 22.212.2 ± 19.613.4 ± 22.610.6 ± 16.2<0.01
Physical activity score (units)354.0 ± 293.5407.7 ± 305.2421.4 ± 289.5435.7 ± 289.3474.8 ± 288.5<0.01
Family history of diabetes (%)16.214.014.612.311.40.02
BMI (kg/m2)25.0 ± 5.925.0 ± 5.524.5 ± 4.724.1 ± 4.424.0 ± 4.3<0.01
Waist circumference (cm)78.5 ± 12.979.1 ± 11.778.4 ± 10.677.3 ± 10.776.2 ± 10.0<0.01
Glucose (mg/dl)81.3 ± 8.881.9 ± 9.081.6 ± 8.582.2 ± 7.782.0 ± 7.40.29
Insulin (μU/ml)12.8 ± 6.912.5 ± 6.511.2 ± 4.910.6 ± 4.710.5 ± 4.8<0.01
Systolic blood pressure (mmHg)111.2 ± 10.8111.5 ± 11.2110.8 ± 10.9109.9 ± 10.2109.2 ± 11.3<0.01
Diastolic blood pressure (mmHg)68.2 ± 10.268.8 ± 10.269.2 ± 9.568.8 ± 9.068.2 ± 9.30.11
Total energy intake (kcal)3,264 ± 1,6503,170 ± 1,5712,943 ± 1,3632,652 ± 1,1892,374 ± 1,127<0.01
Total saturated fat (g)53.4 ± 31.351.6 ± 28.347.8 ± 25.042.3 ± 21.635.2 ± 20.6<0.01
Crude fiber (g)4.7 ± 2.95.4 ± 3.05.6 ± 3.16.0 ± 3.26.7 ± 4.0<0.01
Whole grain (times/week)4.9 ± 7.37.4 ± 8.69.7 ± 9.711.0 ± 9.513.1 ± 11.1<0.01
Magnesium supplementation (mg)1.6 ± 9.44.0 ± 15.79.5 ± 25.217.9 ± 35.969.4 ± 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.