Supplement analysis backed by scientific evidence · PT

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Limited evidenceHeart & metabolic

Guava Leaf Extract

Guava leaf tea, approved in Japan as a food for specified health use for post-meal blood sugar. The supporting trials are small, old and largely from the manufacturer, so the effect on glucose is plausible but weakly established.

Evidence last reviewed: August 2026

What the science says

  • Post-meal blood glucose Limited evidence

    A published account of guava leaf extract tea describes human studies in which drinking it with a meal blunted the rise in blood glucose, attributed to inhibition of alpha-glucosidase and intestinal glucose transport. The trials were small and conducted by the product developer.

  • Mechanism of glucose absorption Limited evidence

    A functional assessment of Psidium guajava leaf extract confirmed inhibition of postprandial glucose absorption in laboratory and short-term testing, consistent with earlier in vitro and in vivo work on intestinal glucose transport. These are mechanistic findings, not long-term glycaemic outcomes.

Dosage & safety

Studied doseJapanese studies used guava leaf tea providing roughly 200 mg of extract taken with each meal. Capsules are commonly sold at 250–500 mg, taken with food.
SafetyGenerally well tolerated; nausea and constipation are occasionally reported. Because it can lower post-meal glucose, watch for hypoglycaemia if combined with insulin, sulfonylureas or acarbose. Not studied in pregnancy. No evidence it lowers HbA1c over time.

Scientific references

Where to buy

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