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Evidence-Based Supplement Research
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Gardenia and Reduced Fasting Blood Glucose Levels

Research synthesisModerate evidenceModerate effect4 studies · 3 beneficial · 1 neutral · 0 harmful

Across 4 studies, 3 reported beneficial effects of crocin (a constituent of Gardenia) on reducing fasting blood glucose (FBG) in clinical populations, with moderate effect sizes in two meta-analyses and a small effect in one review. One small RCT found no significant benefit. The median study duration was 56 days (reported in only 1 study), and the most studied population includes individuals with type 2 diabetes or metabolic syndrome. Evidence suggests a moderate beneficial effect, but the number of studies is small and the neutral RCT highlights potential heterogeneity.

  • Studied populations: individuals with type 2 diabetes, metabolic syndrome

Caveats: Evidence base is small (only 4 studies) — conclusions should be considered preliminary. The evidence comes primarily from meta-analyses of RCTs, but one small RCT (n=28) found no significant effect, suggesting possible heterogeneity or small-study bias. All studies investigated crocin (a constituent of Gardenia), not whole Gardenia extract — direct evidence for whole Gardenia is lacking. Only one study reported a dose (15 mg/day crocin) and duration (56 days), so effective dose range and typical treatment length cannot be reliably established.

Generated Jul 10, 2026
Doses used in studies
  • mg/day: 15 (median 15, IQR 15–15) — 1 study
Time to effect
Median: 8 weeks · IQR 8 weeks–8 weeks · Range 8 weeks–8 weeks — Reported in 1 of 4 studies
Safety in these studies
4 of 4 papers
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