Table 2. Subgroup Analyses of Vitamin D Supplementation and Blood Pressure Levels in the General Population, Update Meta-Analysis of Randomized Controlled Trials, 2019.
| Subgroup | No. of Studies | No. of Participants | SBP |
DBP |
||||
|---|---|---|---|---|---|---|---|---|
| WMD (95% CI) | P | I 2, % | WMD (95% CI) | P | I 2, % | |||
| Sex | ||||||||
| Male | 2 | 211 | 2.49 (−0.33 to 5.31) | .08 | 0 | 0.80 (−1.33 to 2.93) | .46 | 0 |
| Female | 10 | 1,215 | −0.68 (−2.59 to 1.23) | .48 | 55.5 | 0.18 (−0.60 to 0.97) | .65 | 13.2 |
| Mixed | 15 | 2,384 | 0.11 (−0.81 to 1.02) | .82 | 28.6 | 0.14 (−0.49 to 0.76) | .66 | 11.7 |
| Age, y | ||||||||
| <50 | 15 | 1,751 | 0.04 (−0.88 to 0.96) | .93 | 29.7 | 0.23 (−0.43 to 0.88) | .50 | 9.1 |
| ≥50 | 12 | 2,059 | −0.27 (−2.01 to 1.48) | .76 | 55.5 | 0.15 (−0.55 to 0.84) | .68 | 4.0 |
| Region | ||||||||
| United States | 6 | 569 | −0.01 (−2.17 to 2.14) | .99 | 50.3 | −0.09 (−1.11 to 0.92) | .86 | 0 |
| Europe | 12 | 1,698 | −0.61 (−2.20 to 0.97) | .45 | 52.9 | 0.42 (−0.27 to 1.11) | .23 | 19.1 |
| Asia | 5 | 469 | 1.24 (−0.87 to 3.35) | .25 | 0 | −0.06 (−1.57 to 1.44) | .94 | 33.4 |
| Oceania | 4 | 1,074 | −0.06 (−1.67 to 1.56) | .94 | 48.4 | 0.06 (−1.01 to 1.14) | .91 | 0 |
| Baseline obesity status | ||||||||
| Overweight/obese | 9 | 895 | 1.01 (−0.32 to 2.34) | .14 | 26.9 | 0.40 (−0.53 to 1.33) | .40 | 3.4 |
| Not cleara | 18 | 2,915 | −0.41 (−1.25 to 0.43) | .34 | 44.4 | 0.11 (−0.44 to 0.67) | .69 | 7.3 |
| Baseline vitamin D status | ||||||||
| Insufficient/deficient | 11 | 924 | −0.44 (−2.33 to 1.44) | .64 | 51.9 | −0.08 (−0.83 to 0.99) | .86 | 31.3 |
| Not cleara | 16 | 2,886 | −0.10 (−0.80 to 1.00) | .82 | 40.8 | 0.27 (−0.32 to 0.86) | .37 | 0 |
| Sample size | ||||||||
| <200 | 22 | 2,240 | −0.01 (−0.82 to 0.84) | .98 | 47.5 | 0.04 (−0.55 to 0.63) | .88 | 7.8 |
| ≥200 | 5 | 1,570 | −0.03 (−1.41 to 1.35) | .96 | 13.5 | 0.46 (−0.35 to 1.28) | .27 | 0 |
| Type of vitamin D | ||||||||
| Cholecalciferol | 25 | 3,620 | −0.01 (−0.76 to 0.73) | .98 | 46.2 | 0.25 (−0.24 to 0.74) | .32 | 7.3 |
| Ergocalciferol | 2 | 190 | 0.12 (−2.27 to 2.50) | .92 | 0 | −0.73 (−2.63 to 1.17) | .45 | 0 |
| Frequency | ||||||||
| Daily | 18 | 2,053 | −0.36 (−1.74 to 1.02) | .61 | 52.3 | 0.27 (−0.34 to 0.88) | .39 | 26.3 |
| Weekly | 3 | 416 | 0.91 (−0.99 to 2.81) | .35 | 0 | −0.02 (−1.42 to 1.37) | .97 | 0 |
| Fortnightly | 1 | 71 | 3.69 (−0.49 to 7.87) | .08 | — | 1.54 (−1.81 to 4.89) | .37 | — |
| Monthly | 3 | 1,031 | −1.02 (−2.71 to 0.67) | .24 | 0 | −0.11 (−1.21 to 1.00) | .85 | 0 |
| Single dose | 2 | 239 | 1.30 (−1.84 to 4.43) | .42 | 0 | 0.25 (−1.72 to 2.21) | .80 | 0 |
| Durationb | ||||||||
| <6 months | 15 | 1,330 | −0.23 (−1.71 to 1.26) | .76 | 55.8 | 0.11 (−0.58 to 0.80) | .75 | 28.7 |
| ≥6 months | 10 | 2,241 | −0.02 (−1.15 to 1.12) | .98 | 20.9 | 0.26 (−0.44 to 0.97) | .47 | 0.0 |
| Intervention typec | ||||||||
| Vitamin D alone | 18 | 2,774 | 0.16 (−0.69 to 1.00) | .72 | 0 | 0.25 (−0.30 to 0.80) | .38 | 6.0 |
| Vitamin D + calcium | 7 | 867 | −0.65 (−3.66 to 2.37) | .68 | 70.4 | −0.02 (−1.14 to 1.10) | .97 | 0 |
| Intervention amountd | ||||||||
| ≤800 IU/d | 6 | 619 | −1.91 (−4.24 to 0.42) | .15 | 57.9 | −0.66 (−1.75 to 0.43) | .51 | 0 |
| >800 IU/d | 12 | 1,434 | 0.87 (−0.30 to 2.05) | .15 | 30.1 | 0.69 (−0.05 to 1.42) | .07 | 33.1 |
| Risk of bias | ||||||||
| Low | 12 | 1,564 | −0.39 (−1.50 to 0.72) | .49 | 41.4 | 0.23 (−0.55 to 1.00) | .56 | 0 |
| High | 7 | 1,166 | 0.03 (−2.34 to 2.41) | .98 | 63.1 | −0.38 (−1.34 to 0.58) | .44 | 18.2 |
| Unclear | 8 | 1,080 | 0.74 (−0.49 to 1.97) | .24 | 7.0 | 0.53 (−0.26 to 1.32) | .19 | 8.2 |
Abbreviations: —, not applicable/not calculated; CI, confidence interval; DBP, diastolic blood pressure; SBP: systolic blood pressure; WMD, weighted mean difference.
a
“Not clear” is defined as articles that did not specify whether the subjects were overweight/obese or vitamin D insufficient/deficient.
b
Total number of studies in the subgroup is not equal to 27, because 2 trials supplemented vitamin D by single dose (49,54).
c
Total number of studies in the subgroup is not equal to 27, because 2 trials supplemented vitamin D with other mineral or multivitamin nutrient (44,45).
d
This subgroup restricted to trials with daily administration.