Table 1.
Characteristics of the study population by quintiles of magnesium intake levels: the CARDIA study, 1985–86 to 2015–16a,b
| Characteristics | Quintiles of Mg intake levels (mg/1,000 kcal) | Total | P value | ||||
|---|---|---|---|---|---|---|---|
| Q1 (lowest) | Q2 | Q3 | Q4 | Q5 (highest) | |||
| n | 819 | 820 | 819 | 820 | 819 | 4,097 | NA |
| Mg intake | 99.8 | 121.7 | 143.6 | 167.4 | 208.1- | 143.6 | NA |
| (mg/1,000 kcal) | (91.7–105.9) | (116.8–126.7) | (137.8–149.0) | (161.0–174.3) | (193.6–238.2) | (116.8–174.3) | |
| Mg supplementation use (yes, %) | 14.7 | 23.7 | 39.8 | 48.2 | 74.0 | 40.1 | <0.01 |
| Age at YO (year) | 23.5±3.8 | 24.3±3.7 | 25.013.6 | 25.5±3.4 | 26.0±3.2 | 24.9±3.6 | <0.01 |
| Female (%) | 49.2 | 42.4 | 42.7 | 53.2 | 65.9 | 50.7 | <0.01 |
| Blacks (%) | 82.2 | 64.9 | 43.6 | 30.6 | 20.0 | 48.3 | <0.01 |
| Education levels (year) | 13.01±1.81 | 13.75±2.12 | 14.42±2.33 | 15.25±2.35 | 15.57±2.23 | 14.40±2.37 | <0.01 |
| Current smokers (%) | 33.3 | 28.2 | 21.5 | 14.1 | 13.5 | 22.1 | <0.01 |
| Alcohol consumption (ml/day) | 4.86 | 6.09 | 6.72 | 7.12 | 6.09 | 6.28 | 0.03 |
| (0.41–16.10) | (1.01–19.05) | (1.12–16.43) | (1.42–17.40) | (1.39–14.64) | (1.09–16.38) | ||
| Physical activity (EU) | 275.2 | 307.9 | 339.9 | 368.4 | 401.8 | 339.8 | <0.01 |
| (160.5–434.8) | (186.0–501.3) | (213.8–502.6) | (240.9–523.1) | (279.6–559.7) | (212.5–509.1) | ||
| BMI at YO (kg/m2) | 23.27±3.29 | 23.32±3.19 | 23.18±2.75 | 23.10±2.73 | 22.73±2.72 | 23.12±2.95 | <0.01 |
| SBP (mmHg) | 111.97±9.62 | 111.82±9.53 | 110.77±9.23 | 109.73±9.28 | 107.90±9.58 | 110.44±9.56 | <0.01 |
| DBP (mmHg) | 70.62±7.77 | 70.36±8.12 | 70.09±7.42 | 69.40±7.29 | 68.13±7.32 | 69.72±7.64 | <0.01 |
| Total cholesterol (mg/dL) | 175.2±29.8 | 181.7±31.0 | 183.7±30.3 | 182.9±28.2 | 181.3±26.9 | 181.0±29.4 | <0.01 |
| HDL/LDL cholesterol ratio | 0.56±0.27 | 0.52±0.23 | 0.51±0.26 | 0.53±0.21 | 0.58±0.22 | 0.54±0.24 | <0.01 |
| Triglycerides (mg/dL) | 81.88±39.92 | 88.34±57.81 | 88.18±50.25 | 87.26±62.33 | 79.27±43 | 84.99±51.48 | <0.01 |
| Glucose (mg/dL) | 87.31 ±12.83 | 89.68±16.51 | 89.76±18.16 | 90.03±11.28 | 89.07±12.00 | 89.17±14.44 | <0.01 |
| Diabetes ever (yes, %) | 5.4 | 6.1 | 5.3 | 6.1 | 3.44 | 6.4 | 0.09 |
| Hypertension ever (yes, %) | 51.2 | 49.8 | 47.4 | 46.1 | 38.6 | 46.6 | <0.01 |
| Intake of whole grain (servings/day) | 0.83±0.91 | 1.29±1.10 | 1.68±1.42 | 1.83±1.31 | 2.13±1.47 | 1.55±1.34 | <0.01 |
| Intake of nuts and seeds (servings/day) | 0.39±0.70 | 0.62±1.13 | 0.79±1.20 | 0.98±1.44 | 1.20±1.61 | 0.80±1.29 | <0.01 |
| Intake of legumes (servings/day) | 0.21 ±0.41 | 0.24±0.34 | 0.22±0.35 | 0.22±0.30 | 0.27±0.40 | 0.23±0.36 | 0.02 |
| Intake of dark-green vegetables (servings/day) | 0.18±0.22 | 0.30±0.41 | 0.40±0.52 | 0.60±0.58 | 0.88±0.95 | 0.47±0.64 | <0.01 |
| A Priori Diet Quality Score (points) | 54.9±9.0 | 61.9±10.2 | 67.6±10.4 | 75.1±10.6 | 79.4±10.5 | 68.0±13.4 | <0.01 |
Abbreviations: BMI, body mass index; CARDIA, Coronary Artery Risk Development in Young Adults; DBP, diastolic blood pressure; EU, exercise unit; IQR, inter-quartile range; Mg, magnesium; NA, not applicable; Q, quintile; SBP, systolic blood pressure; SD, standard deviation, Y, exam year.
Blood pressure and lipid profile were measured at Y0 and each follow-up exam. Glucose was measured at Y0, 7, 10, 15, 20, 25, and 30. Values of covariates, if not specified, were calculated as the cumulative averages of repeated measurements by incident obesity or last follow-up.Smoking status at the time of incident obesity or last follow-up was used.
Results are presented by means ± SDs, medians (IQRs), or proportions. P values are for any difference across quintiles of Mg intake levels using analysis of variance, Kruskal Wallis test, or chi-squared test, as appropriate.