The Promising Link Between Green Tea & Alzheimer's, Explained

According to the authors of a 2022 study published in Nature Communications, Alzheimer's disease occurs when tau protein clumps into fibrous tangles that spread between brain cells, leading to their death. However, they found that a molecule found in green tea, epigallocatechin gallate (EGCG), could help break apart the protein tangles associated with Alzheimer's disease.

To study the actions of EGCG on these proteins, the team analyzed tau tangles from the brains of people who had Alzheimer's. Using cryogenic electron microscopy, they demonstrated that EGCG is capable of binding to small openings in tau fibers, destabilizing and pulling them apart.  

However, the researchers said that EGCG is not able to penetrate the brain very well, and it interacts with other proteins besides tau. They felt that if they could identify other molecules with similar action to EGCG that are able to pass into the brain more effectively, this could lead to promising new Alzheimer's medications. They used computer modeling to look for molecules that might act in a similar manner while also being more effective at entering the brain. In both lab and tissue tests, several of these candidates untangled tau and limited new tau formation.

While the 2022 study states that the EGCG present in green tea is not good at making its way into the brain where it's needed, a 2025 study found in npj Science of Food suggests that drinking green tea may still be helpful when it comes to reducing your chances of developing dementia.

This study examined whether there was any link between green tea or coffee drinking and cerebral white matter lesions and hippocampal and total brain volumes. The scientists used people's own self-reported consumption of these beverages and performed magnetic resonance imaging (MRI) to investigate cerebral white matter lesions, hippocampal volume, and total brain volume. After analyzing the data, they found that there was a correlation between higher green tea intake and fewer cerebral white matter lesions. Coffee, however, did not produce the same result.

Given the quality of the evidence and high potential for benefit, as well as its good safety profile, green tea appears to be a worthwhile addition to your diet if you're looking to preserve cognitive function and prevent dementia. 

According to the experts at Cognitive Vitality, there are multiple studies showing that drinking green tea is linked with a lower risk of dementia and cognitive decline. Studies have also found that moderate green tea consumption, which they define as three to five cups per day, is safe with only mild side effects. 

Green tea supplements at high doses, however, may lead to gastrointestinal problems, elevated liver enzymes, and sleep issues. Additionally, there are certain medications that may interact with green tea, including warfarin, anisindione, and dicumarol. Green tea can also deplete folic acid and interfere with iron absorption.