Supplement analysis backed by scientific evidence · PT

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Limited evidenceGeneral health

Matcha Green Tea

Powdered whole green tea leaf, so you swallow the leaf rather than an infusion. It reliably delivers caffeine and L-theanine; the trials on cognition, mood and metabolism are small and their results are inconsistent.

Evidence last reviewed: August 2026

What the science says

  • Cognition in older adults Limited evidence

    A 12-month randomised trial in older adults with cognitive decline found improvement in social cognition and sleep quality but not in general cognitive scores, and an earlier randomised study in community-dwelling elderly found no clear cognitive benefit. The picture across trials is mixed.

  • Attention under mild stress Limited evidence

    Several small randomised placebo-controlled studies by one Japanese group reported that daily matcha helped maintain attention after a mild psychological stressor. Effects were small, measured on task batteries, and largely attributable to caffeine plus theanine.

  • Weight and metabolic effects of green tea catechins Moderate evidence

    A systematic review and meta-analysis of randomised trials found that green tea catechins add a small amount to weight loss achieved with exercise in people with overweight or obesity. The effect is real but of little practical size, and the trials used catechin doses higher than a cup of matcha provides.

Dosage & safety

Studied doseTrials used roughly 2–4 g of matcha powder per day (about one to two teaspoons), providing perhaps 40–80 mg of caffeine and 20–40 mg of L-theanine.
SafetyContains caffeine, so it can disturb sleep and worsen anxiety or palpitations. Because you consume the whole leaf, matcha delivers more lead and other leaf-bound contaminants than brewed tea; choose tested sources. Concentrated green tea extracts (not the powder itself) have been linked to rare liver injury. Green tea reduces non-heme iron absorption when taken with meals.

Scientific references

Where to buy

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