Red Grape

What does the research say about Red Grape?

2 health outcomes synthesised

Research on red grape extract has examined its effects on 2 health outcomes related to liver health, with the strongest evidence supporting a reduction in aspartate aminotransferase (AST) levels (4 studies, moderate evidence). Doses in clinical studies range from 100–520 mg/day, and effects have been observed in populations with non-alcoholic fatty liver disease (NAFLD) and thalassemia patients with iron overload.

Strongest evidence: The most robust finding is for reduced aspartate aminotransferase (AST) levels, supported by 3 beneficial studies out of 4 (moderate evidence). The predominant effect size was small, though one study showed a moderate effect. Doses varied from 100–520 mg/day, and the median study duration was about 44 days. Populations studied included people with NAFLD and thalassemia patients.

Mixed or weaker evidence: Evidence for reduced alanine aminotransferase (ALT) levels is weaker (low evidence). Of 3 studies, 2 showed beneficial effects (small to moderate magnitude), and 1 was neutral. The most studied population was NAFLD patients, and the only reported effective dose was 520 mg/day of grape seed extract. The clinical significance of the ALT reduction remains unclear.

Effective dose patterns: No single effective dose emerged across outcomes. For AST, doses ranged from 100–520 mg/day, while for ALT, the only active dose was 520 mg/day of grape seed extract. The variation in forms (whole red grape extract vs. grape seed extract vs. mixed flavonoids) makes dose comparisons difficult.

Population insights: Both outcomes were studied primarily in clinical populations — NAFLD and thalassemia patients. No data are available for general healthy populations, limiting generalizability. Effects may be population- or form-specific, as the neutral studies in each synthesis used different compounds (quercetin, curcumin) or different populations (thalassemia for ALT).

Notable caveats: The evidence base is small (4 and 3 studies), so conclusions are preliminary. Studies used different forms of red grape (extract, seed extract, mixed flavonoids), not always whole red grape. Sample sizes were small (n=30 and n=25 in some RCTs), and study durations were short (28–60 days). The neutral study in the AST synthesis evaluated quercetin and curcumin, which may not be comparable to red grape extract.

Frequently asked

What is red grape good for according to research?
Research on red grape extract has focused on two liver-related outcomes: reducing aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels. The strongest evidence is for AST reduction (3 of 4 studies beneficial, moderate evidence), while ALT reduction has weaker support (2 of 3 studies beneficial, low evidence).
What dose of red grape is typically used in studies?
Doses in the reviewed studies ranged from 100–520 mg/day, but forms varied (whole red grape extract, grape seed extract, mixed flavonoids). The only specific effective dose reported was 520 mg/day of grape seed extract for ALT reduction. No standardized effective dose has been established.
Who benefits most from red grape?
The studies were conducted in clinical populations — people with non-alcoholic fatty liver disease (NAFLD) and thalassemia patients with iron overload. Effects may be specific to these groups, and no data are available for healthy individuals. One neutral study in thalassemia patients using quercetin (not red grape) suggests effects may be population- and form-specific.
Are there caveats or limitations in the research on red grape?
The evidence base is small (3–4 studies per outcome) and considered preliminary. Study designs varied in form of extract, dose, and duration (28–60 days). Sample sizes were small, and some neutral studies used compounds not directly comparable to red grape extract. Clinical significance of the effects remains unclear.
Does red grape help reduce AST levels?
Yes, 3 out of 4 studies showed beneficial effects on reducing aspartate aminotransferase (AST) levels, with moderate evidence strength. The effect size was generally small, though one study reported a moderate effect. Effects were observed in NAFLD and thalassemia patients over a median of 44 days.
Does red grape help reduce ALT levels?
The evidence is weaker: 2 of 3 studies showed beneficial effects on alanine aminotransferase (ALT) levels, with low evidence strength. Effect sizes ranged from small to moderate. The only effective dose identified was 520 mg/day of grape seed extract in NAFLD patients. One neutral study used quercetin in a different population.

Most-studied combinations with Red Grape

most supplement research is combination research

Also studied with:Ginkgo (2)