Big effect
In an open-label 12-week trial, 150 mg of grape seed extract twice daily significantly reduced venous reflux time in both superficial and deep veins — but the lack of blinding means belief in the result should be tempered.
This is among the first controlled trials to show grape seed extract can meaningfully improve a physical measure of vein function in people with varicose veins, but because both researchers and participants knew who was getting the supplement, the placebo effect and observer bias can't be ruled out.
The study found that people with varicose veins who took 150 mg of grape seed extract twice daily for 12 weeks had a measurable decrease in how long blood pooled in their leg veins — an objective sign of improved vein function. They also reported fewer symptoms and better quality of life. However, the trial was open-label (no placebo control), so the symptom improvements in particular could partly reflect wishful thinking, and this is a new area of research with few supporting studies yet.
Where this fits in the evidence
This is among the first studies we've indexed on Grape for Reduced Venous Reflux Time — treat it as an early signal until more research accumulates.
The study
- Randomized Controlled Trial (RCT)
- n = 176
- 2026-01
- Journal of vascular surgery. Venous and lymphatic disorders
This is a plain-language summary of a research finding, not medical advice. Pillser surfaces research signals to help you decide what's worth investigating — always consult a qualified professional before changing what you take.