Green tea keeps showing up in wellness advice, and the research does back some of the claims, though not all. A 2025 scientific review in the International Journal of Molecular Sciences summed up the current evidence on epigallocatechin gallate, or EGCG, the main active compound in green tea. It points to antioxidant, anti-inflammatory, cardiovascular and neuroprotective effects, most of them modest.
The clearest cardiovascular signal comes from a meta-analysis of 20 randomized controlled trials with 1,536 participants, published in Nutrition, Metabolism and Cardiovascular Diseases. Green tea intake produced a small drop in systolic blood pressure of 1.94 mmHg and a moderate reduction in LDL cholesterol of 0.19 mmol per liter compared with control groups.
The cardiovascular picture
The 2025 review notes that EGCG intake reduced LDL cholesterol in trials using doses of 107 to 856 mg daily over 4 to 14 weeks. It also flags mechanisms that go beyond cholesterol, including effects on platelet aggregation and inflammation.
None of this is on the scale of a statin. The authors of the 2014 meta-analysis themselves describe the blood pressure effect as small and the cholesterol effect as moderate. Green tea is a plausible add-on for people watching their heart risk, not a replacement for medication or diet changes.
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A modest edge against colds and flu
A separate meta-analysis, published in the European Journal of Nutrition in September 2021, pooled data from 3,748 subjects across six randomized trials and four prospective cohort studies. Tea catechin consumption and tea gargling were linked to a lower risk of upper respiratory tract infections, with a risk ratio of 0.74. For influenza specifically, the risk ratio was 0.69.
The authors called for more research before recommending tea as a public health measure, but the direction of the evidence is consistent.
What about the brain?
EGCG crosses the blood-brain barrier and, in laboratory and animal studies, reduces markers linked to Alzheimer's and other neurodegenerative diseases. The 2025 review describes these effects in cell and animal models, not settled human outcomes.
A separate 2025 review in Molecules concluded that catechins may have a role in alleviating neurodegenerative diseases such as Alzheimer's, Parkinson's and multiple sclerosis, based on in vivo and in vitro studies. Human trials on cognition are smaller and less conclusive than the cardiovascular data.
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The supplement warning most articles skip
Drinking brewed green tea is safe. According to the NIH LiverTox database, regular tea drinking has not been linked to liver injury, and users tend to show lower, not higher, liver enzyme levels.
Concentrated extracts are a different product. LiverTox has cataloged more than 100 published cases of clinically apparent liver injury linked to green tea extract supplements. The US Pharmacopeia's expert panel concluded that green tea extract can cause liver injury and should carry a warning label, particularly for people who take it on an empty stomach.
The European Food Safety Authority has set a specific threshold. As the 2025 EGCG review notes, consuming 800 mg or more of EGCG a day may raise liver enzymes. A typical cup of green tea contains 50 to 100 mg of EGCG, so reaching that dose from tea alone would be difficult. Pill-form extracts can hit it in a single capsule.
Anyone with liver disease, on medication, or considering high-dose green tea supplements should talk to a doctor before starting.
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