Table 2.
Subgroup analyses for the effects of vitamin E supplementation on inflammatory biomarkers in adults aged ≥ 20 years.
| Effect size, n | WMD (95% CI)a | P-withinb | I2 (%)c | P-heterogeneityd | |
|---|---|---|---|---|---|
| Vitamin E supplementation on serum CRP concentrations | |||||
| Overall | 36 | − 0.43 (− 0.54, − 0.33) | < 0.001 | 59.9 | < 0.001 |
| Intervention duration (week) | |||||
| < 8 | 16 | − 0.35 (− 0.72, 0.01) | 0.059 | 47.6 | 0.018 |
| ≥ 8 | 20 | − 0.44 (− 0.55, − 0.33) | < 0.001 | 67.5 | < 0.001 |
| Type of vitamin E | |||||
| α-Tocopherol | 26 | − 0.42 (− 0.59, − 0.25) | < 0.001 | 66.9 | < 0.001 |
| γ-Tocopherol | 4 | − 0.19 (− 1.11, 0.73) | 0.685 | 0.0 | 0.542 |
| Mixed-tocopherols | 6 | − 0.45 (− 0.59, − 0.31) | < 0.001 | 46.7 | 0.095 |
| Dosage of vitamin E (mg/day) | |||||
| < 500 | 19 | − 0.18 (− 0.42, 0.06) | 0.135 | 29.0 | 0.115 |
| ≥ 500 | 17 | − 0.50 (− 0.61, − 0.38) | < 0.001 | 71.8 | < 0.001 |
| Health condition | |||||
| Healthy | 5 | 0.04 (− 0.88, 0.96) | 0.933 | 0.0 | 0.885 |
| Unhealthy | 31 | − 0.44 (− 0.55, − 0.33) | < 0.001 | 64.8 | < 0.001 |
| Insulin resistance-related disorders | 13 | − 0.39 (− 0.51, − 0.26) | < 0.001 | 39.4 | 0.071 |
| CVDs | 5 | − 1.25 (− 1.75, − 0.75) | < 0.001 | 79.0 | 0.001 |
| Hemodialysis | 9 | − 0.41 (− 0.67, − 0.15) | 0.002 | 62.1 | 0.007 |
| Rheumatoid arthritis | 2 | − 1.40 (− 4.13, 1.34) | 0.317 | 30.0 | 0.232 |
| Other disease | 2 | − 1.06 (− 2.06, − 0.07) | 0.037 | 90.9 | 0.001 |
| Baseline concentrations of CRP (mg/L) | |||||
| Normal (< 3 mg/L) | 18 | − 0.31 (− 0.51, − 0.10) | 0.004 | 69.0 | < 0.001 |
| Elevated (≥ 3 mg/L) | 18 | − 0.48 (− 0.60, − 0.35) | < 0.001 | 44.4 | 0.022 |
| Adjustment for baseline values | |||||
| Adjusted | 14 | − 0.39 (− 0.50, − 0.27) | < 0.001 | 60.5 | 0.002 |
| Non-adjusted | 22 | − 0.76 (− 1.07, − 0.45) | < 0.001 | 57.6 | < 0.001 |
| Vitamin E supplementation on serum IL-6 concentrations | |||||
| Overall | 21 | − 0.14 (− 0.29, 0.01) | 0.06 | 74.3 | < 0.001 |
| Intervention duration (week) | |||||
| < 8 | 11 | − 0.12 (− 0.32, 0.07) | 0.220 | 80.6 | < 0.001 |
| ≥ 8 | 10 | − 0.17 (− 0.40, 0.06) | 0.145 | 65.7 | 0.002 |
| Type of vitamin E | |||||
| α-Tocopherol | 15 | − 0.21 (− 0.39, − 0.03) | 0.023 | 79.2 | < 0.001 |
| γ-Tocopherol | 2 | 0.08 (− 0.34, 0.50) | 0.717 | 81.6 | 0.020 |
| Mixed-tocopherols | 4 | − 0.05 (− 0.40, 0.29) | 0.760 | 10.2 | 0.342 |
| Dosage of vitamin E (mg/day) | |||||
| < 500 | 12 | − 0.14 (− 0.34, 0.06) | 0.177 | 82.0 | < 0.001 |
| ≥ 500 | 9 | − 0.15 (− 0.37, 0.07) | 0.190 | 52.5 | 0.032 |
| Health condition | |||||
| Healthy | 3 | 0.37 (− 0.05, 0.79) | 0.086 | 0.0 | 0.387 |
| Unhealthy | 18 | − 0.22 (− 0.38, − 0.06) | 0.008 | 75.5 | < 0.001 |
| Insulin resistance-related disorders | 11 | − 0.22 (− 0.40, − 0.05) | 0.010 | 67.0 | 0.001 |
| CVDs | 1 | 0.20 (− 0.30, 0.70) | 0.435 | – | – |
| Hemodialysis | 5 | − 0.04 (− 1.45, 1.38) | 0.960 | 71.8 | 0.007 |
| Other disease | 1 | − 3.96 (− 5.51, − 2.41) | < 0.001 | – | – |
| Baseline concentrations of IL-6 (pg/mL) | |||||
| Normal (< 4.4 pg/mL) | 15 | − 0.13 (− 0.28, 0.03) | 0.109 | 66.7 | < 0.001 |
| Elevated (≥ 4.4 pg/mL) | 6 | − 0.50 (− 1.18, 0.18) | 0.150 | 85.6 | < 0.001 |
| Adjustment for baseline values | |||||
| Adjusted | 4 | − 0.27 (− 0.56, 0.02) | 0.073 | 53.7 | 0.090 |
| Non-adjusted | 17 | − 0.10 (− 0.27, 0.08) | 0.264 | 77.3 | < 0.001 |
| Vitamin E supplementation on serum TNF-α concentrations | |||||
| Overall | 19 | − 0.03 (− 0.09, 0.02) | 0.25 | 78.9 | < 0.001 |
| Intervention duration (week) | |||||
| < 8 | 8 | − 0.07 (− 0.13, − 0.01) | 0.026 | 32.0 | 0.173 |
| ≥ 8 | 11 | 0.12 (− 0.00, 0.25) | 0.052 | 85.2 | < 0.001 |
| Type of vitamin E | |||||
| α-Tocopherol | 14 | 0.02 (− 0.06, 0.09) | 0.655 | 82.7 | < 0.001 |
| γ-Tocopherol | 2 | − 0.15 (− 0.29, − 0.01) | 0.040 | 0.0 | 0.358 |
| Mixed-tocopherols | 3 | − 0.06 (− 0.15, 0.04) | 0.238 | 57.8 | 0.093 |
| Dosage of vitamin E (mg/day) | |||||
| < 500 | 11 | 0.12 (− 0.00, 0.25) | 0.052 | 72.4 | < 0.001 |
| ≥ 500 | 8 | − 0.07 (− 0.13, − 0.01) | 0.027 | 83.2 | < 0.001 |
| Health condition | |||||
| Healthy | 3 | − 0.22 (− 0.46, 0.02) | 0.072 | 39.9 | 0.189 |
| Unhealthy | 16 | − 0.02 (− 0.08, 0.03) | 0.449 | 81.1 | < 0.001 |
| Insulin resistance-related disorders | 13 | − 0.02 (− 0.08, 0.03) | 0.439 | 84.8 | < 0.001 |
| CVD | 1 | 0.30 (− 0.99, 1.59) | 0.650 | – | – |
| Rheumatoid arthritis | 2 | − 0.04 (− 1.29, 1.21) | 0.944 | 0.0 | 0.994 |
| Baseline concentrations of TNF-α (pg/mL) | |||||
| Normal (< 2.3 pg/mL) | 8 | − 0.04 (− 0.10, 0.01) | 0.125 | 66.1 | 0.004 |
| Elevated (≥ 2.3 pg/mL) | 11 | 0.46 (0.10, 0.83) | 0.013 | 82.5 | < 0.001 |
| Adjustment for baseline values | |||||
| Adjusted | 5 | − 0.01 (− 0.09, 0.07) | 0.820 | 92.0 | < 0.001 |
| Non-adjusted | 14 | − 0.05 (− 0.12, 0.02) | 0.177 | 62.5 | 0.001 |
WMD weighted mean difference, CI confidence interval, CRP C-reactive protein, IL-6 interleukin-6, TNF-α tumor necrosis factor-α.
aObtained from the fixed-effects model.
bRefers to the mean (95% CI).
cInconsistency, percentage of variation across studies due to heterogeneity.
dObtained from the Q-test.