Table 2.
Main meta-analyses investigating the correlation between vitamin C intake or its plasma levels and cardiovascular disease (CVD).
| Meta-Analysis Topic | Number of Studies | Total Participants (n) | Trial Duration | Vitamin C Supplement Dosage | Outcome | Ref. |
|---|---|---|---|---|---|---|
| Coronary Heart Disease | 14 cohorts | 374,488 | mean duration: 10 y. | Not reported | Dietary Vitamin C had an inverse association with CHD risk, but supplement intake of Vitamin C had no significant association with CHD risk. | [154] |
| Hypertension | 29 trials | 1407 | mean duration: 8 wks. | 60 to 4000 mg/day (median 500 mg/day) | Daily supplementation of Vitamin C in hypertensive participants reduced systolic BP by 3.84 mm Hg and DBP by 1.48 mm Hg. | [159] |
| Coronary Heart Disease | 15 trials | 188,209 | from 1.4 y. to 12 y. | 120 to 1000 mg/day | Vitamin C in association with Vitamin E and beta-carotene had no effect on CHD or other major cardiovascular events. Vitamin C in association with Vitamin E and beta-carotene had no effect on stroke risk compared to placebo. |
[156] |
| Stroke | 16 cohorts | 217,454 participants for studies on Vitamin C intake 29,648 participants for studies on circulating Vitamin C |
from 6.1 y. to 30 y. | 45 to 1167 mg/day | 19% lower risk of stroke (pooled analysis of 2 studies) comparing the highest to the lowest dietary Vitamin C intakes. 38% lower risk of stroke (pooled analysis of 6 studies) with the highest versus lowest circulating Vitamin C concentrations. |
[160] |
| Endothelial function | 44 trials | 1324 | from 1 d. to 8 wks. | 500 to 2000 mg/day | A significant positive effect of Vitamin C supplementation on endothelial function measured by flow-mediated dilation (19 trials), evaluating pulse-wave (5 trials) and forearm blood flow (20 trials). | [161] |
| Arterial stiffness | 22 trials | 1909 | from 1 d. to 7 y. (mean duration: 56 d.) | 120 to 4000 mg/day (mean 2000 mg/day) | Association of Vitamin C with Vitamin E and β–carotene improved arterial stiffness irrespective of the age group | [161] |
| Cardiovascular events | 8 trials | 15,445 | mean duration: 8 y. |
– | Inconsistent or low-quality (downgraded) evidence for the correlation between Vitamin C supplementation and major cardiovascular events or cardiovascular mortality | [157] |
| Hypertension | 11 cross-sectional studies and 7 case-control studies | 22,200 | – | – | Serum Vitamin C level was significantly lower in hypertensive compared to normotensive subjects. Inverse correlation between serum Vitamin C concentration and SBP or DBP. |
[162] |
| Hypertension | 8 trials | 614 | from 4 wks. to 24 wks. | 300 to 1000 mg/day | Significantly reduced SBP and DBP in the subgroups of age ≥35 and ≥60 years with Vitamin C supplementation ≥500 mg/day for 6 weeks or more. | [163] |
| Cardiovascular mortality | 15 trials | 320,548 | from 4 to 22y. | 50 to 450 mg/day | Higher Vitamin C intake is associated with a lower risk of cardiovascular mortality | [164] |