Does green tea reduce the risk of dementia?

Green Tea and Dementia Risk Reduction

Green tea consumption reduces the risk of dementia, with each additional cup per day associated with approximately a 4-5% risk reduction, and optimal benefits seen at 1-3 cups daily. 1, 2

Evidence for Protective Effects

Dose-Response Relationship

• A 12-year Japanese cohort study of 13,660 adults demonstrated that each cup (150 mL) of green tea per day was associated with a 4.8% reduction in dementia risk (adjusted HR = 0.952,95% CI: 0.92-0.99). 1
• The highest quartile of green tea consumers showed a 25% lower dementia risk compared to the lowest quartile (adjusted HR = 0.75). 1
• A 2024 meta-analysis of 38 cohort studies confirmed a linear dose-response relationship, with each additional cup per day decreasing dementia risk by 4% (RR = 0.96,95% CI: 0.94-0.99). 2

Magnitude of Benefit

• The pooled analysis of 6 cohort studies showed that highest category green tea consumers had a 16% lower dementia risk compared to lowest consumers (RR = 0.84,95% CI: 0.74-0.96). 2
• For Alzheimer's disease specifically, the highest green tea consumption category showed a borderline 7% risk reduction (RR = 0.93,95% CI: 0.87-1.00). 2

Mechanistic Basis from Guidelines

Neuroprotective Pathways

• Green tea contains the polyphenol EGCG (epigallocatechin gallate), which inhibits mTOR signaling—a pathway implicated in protein aggregation seen in Alzheimer's disease and other aging-related diseases. 3
• EGCG can directly reduce amyloid-beta oligomer formation and tau fibrillization, the pathological hallmarks of Alzheimer's disease. 3
• Both EGCG and its intestinal microbiota degradation products promote neuronal differentiation and suppress brain aging through activation of nerve cells. 4

Additional Components

• Green tea's theanine and arginine content provides stress-reducing effects, which indirectly protect against accelerated brain aging caused by chronic stress. 4

Clinical Recommendations

Optimal Consumption Pattern

• Aim for 1-3 cups (150-450 mL) of brewed green tea daily for dementia prevention. 1, 2
• This range provides cardiovascular benefits (5% reduction in cardiovascular mortality per cup) while avoiding excessive caffeine intake. 5

Important Caveats

• Excessive consumption of both green tea and coffee together is not recommended, as the Japanese cohort study found no additive benefit and a significant interaction (P = 0.0210), suggesting potential antagonism at very high combined intakes. 1
• Healthy adults should limit total caffeine intake to ≤400 mg daily (approximately 8-10 cups of tea maximum) to avoid adverse effects including agitation, anxiety, and sleep disturbance. 6
• Pregnant women should restrict green tea to 4-6 cups daily maximum (200-300 mg caffeine limit). 6

Population-Specific Considerations

• The protective effect appears stronger in men than women, though the mechanism for this sex difference remains unclear. 7
• Benefits may be more pronounced in the 60-69 age group compared to younger or older individuals. 7

Guideline Context

• The 2015 ESPEN Guidelines on Nutrition in Dementia do not recommend any specific nutritional product, including polyphenols from green tea, for correcting cognitive impairment due to insufficient high-level evidence at that time. 3
• However, more recent cohort data (2021-2025) provides substantially stronger evidence supporting green tea's protective role. 1, 2, 7

Practical Implementation

For dementia risk reduction in middle-aged and older adults, consume 2-3 cups of brewed green tea daily as part of a comprehensive dietary pattern. 1, 2 This recommendation balances the demonstrated dose-response benefit against the risk of excessive caffeine intake and aligns with cardiovascular health guidelines. 5