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Evidence-Based Supplement Research
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Red Grape

What does the research say about Red Grape?

4 health outcomes synthesised

Red Grape (primarily studied as grape seed extract) has been investigated across 4 health outcomes in clinical research. The strongest evidence is for reducing diastolic blood pressure, where 4 studies consistently showed small but beneficial effects, typically in adults with elevated blood pressure or metabolic conditions at doses around 520 mg/day. Research also suggests potential benefits for liver enzyme levels, though the evidence is more preliminary.

Strongest evidence

  • Reduced Diastolic Blood Pressure: 4 of 4 studies reported beneficial effects with moderate evidence strength, all showing a small effect size. Studies lasted a median of 34 days, and the most common dose was 520 mg/day of grape seed extract, tested in adults with hypertension, metabolic syndrome, or NAFLD.
  • Reduced Aspartate Aminotransferase (AST) Level: 3 of 4 studies showed benefits (small to moderate effect sizes) with moderate evidence, primarily in patients with NAFLD or β-thalassemia. Doses ranged from 100–520 mg/day over 4–8 weeks.
  • Reduced Alanine Aminotransferase (ALT) Level: 2 of 3 studies reported beneficial effects (small to moderate) in people with NAFLD, with moderate evidence. One study used grape seed extract 520 mg/day for 60 days.

Mixed or weaker evidence

  • Reduced Systolic Blood Pressure: Low evidence strength; only 2 of 4 studies found small benefits, while 2 found no effect. Results were inconsistent, and one meta-analysis showed high heterogeneity. A 60-day study showed benefit, but a 7-day study did not, suggesting duration may matter.

Effective dose patterns The most commonly used dose across multiple outcomes was 520 mg/day of grape seed extract, typically for 4–8 weeks. A lower dose of 100 mg/day was also effective for AST reduction in one study. No single effective dose was consistently identified across all outcomes, and many studies did not report dosage.

Population insights Beneficial effects were most consistently observed in clinical populations—adults with elevated blood pressure, metabolic syndrome, or NAFLD. Limited data exist for healthy individuals, and one neutral study for AST involved quercetin/curcumin rather than grape extract, suggesting form-specific effects.

Notable caveats

  • All studies used grape seed extract, not whole red grape, so effects may not generalize to other forms.
  • The evidence base is small (3–4 studies per outcome), and conclusions are preliminary.
  • Publication bias is a concern: null-result studies are less likely to be published.
  • Doses and durations varied widely across studies, limiting comparability.

Frequently asked

  • What is Red Grape good for according to research?
    Research on red grape (mainly grape seed extract) shows the strongest evidence for reducing diastolic blood pressure in adults with hypertension or metabolic conditions. There is also moderate evidence for reducing liver enzymes (AST and ALT) in people with NAFLD. Effects on systolic blood pressure are inconsistent.
  • What dose of Red Grape is typically used in studies?
    The most commonly reported dose in studies was 520 mg/day of grape seed extract, taken for 4 to 8 weeks. One study used a lower dose of 100 mg/day for AST reduction. However, many studies did not specify a dose, so these ranges are based on limited data.
  • Who benefits most from Red Grape?
    Most studies were conducted in specific clinical populations—adults with elevated blood pressure, metabolic syndrome, or non-alcoholic fatty liver disease (NAFLD). Evidence for benefits in healthy individuals is limited, and results may not generalize.
  • Are there caveats or limitations in the research on Red Grape?
    Yes, several caveats apply. All studies used grape seed extract, not whole red grape, so effects may differ for other forms. The number of studies per outcome is small (3–4), and publication bias is possible—null-result studies are less likely to be published. Doses and durations were inconsistent across studies.
  • Does Red Grape help reduce blood pressure?
    Research shows moderate evidence for a small reduction in diastolic blood pressure, with all 4 studies reporting benefits. For systolic blood pressure, evidence is weaker—only 2 of 4 studies found a small effect, and results were inconsistent, suggesting duration of supplementation may matter.
  • Can Red Grape lower liver enzymes?
    Moderate evidence from 4 studies indicates red grape (grape seed extract) may reduce aspartate aminotransferase (AST) levels, with 3 of 4 studies showing benefit. For alanine aminotransferase (ALT), 2 of 3 studies reported small to moderate reductions. Effects were primarily seen in people with NAFLD.

Most-studied combinations with Red Grape

most supplement research is combination research
Also studied with:Turmeric (2), Ginkgo (2), Thistle (2)
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