Across 3 studies, 2 reported beneficial effects of vitamin C on reducing diastolic blood pressure, with effect sizes ranging from small to large. The median study duration was 40 days, and the most-studied population was adults, including specific subgroups such as patients with diabetes and heat-exposed workers. Evidence is limited by the small number of studies and mixed findings, including one neutral result.
Caveats: Evidence base is small (only 3 studies) — conclusions should be considered preliminary. One study reported a large effect (7.93 mmHg reduction) in a specific population (heat-exposed workers), while another meta-analysis found a small but clinically important reduction in patients with diabetes; however, a third study in young healthy participants found no significant effect. The small sample sizes and lack of consistent dosing limit generalizability.
a clinically important reduction was observed in patients with diabetes (-2.27 mmHg)
There were no significant differences for any of the vascular outcomes between the three interventions groups.
diastolic BP (DBP) ... decreased by 7.93 mmHg