Green tea (Camelia sinensis) has long been considered a brain-boosting botanical. But exactly how it works is still being studied. One of the components of green tea, epigallocatechin gallate (EGCG) and epigallocatechin (EGC) are capable of crossing the blood-brain barrier to protect neuronal cells and promote their resilience.

But while those components, especially EGCG, along with caffeine inherent in the tea may spark greater brain cell connection and action, it may also create stress. That, in turn, could cause oxidation and inflammation in the very tissues that green tea components are simultaneously helping.

So how does green tea get its great reputation? Through its balance of compounds that help keep your brain young. It turns out that the relaxing, anti-stress effects of l-theanine and arginine, two amino acids in green tea help counteract any potential issues brought about by nerve cell activation from EGCG and caffeine.

The ratios of green tea components truly matter, so even though EGCG as a stand-alone compound can be highly beneficial, the other nutrients are also key to the positive effects of this amazing herbal medicine and popular drink.

Abstract:

Unno K, Nakamura Y. Green Tea Suppresses Brain Aging. Molecules. 2021 Aug 12;26(16):4897. doi: 10.3390/molecules26164897. PMID: 34443485; PMCID: PMC8401650.

Epidemiological studies have demonstrated that the intake of green tea is effective in reducing the risk of dementia. The most important component of green tea is epigallocatechin gallate (EGCG). Both EGCG and epigallocatechin (EGC) have been suggested to cross the blood-brain barrier to reach the brain parenchyma, but EGCG has been found to be more effective than EGC in promoting neuronal differentiation. It has also been suggested that the products of EGCG decomposition by the intestinal microbiota promote the differentiation of nerve cells and that both EGCG and its degradation products act on nerve cells with a time lag. On the other hand, the free amino acids theanine and arginine contained in green tea have stress-reducing effects. While long-term stress accelerates the aging of the brain, theanine and arginine suppress the aging of the brain due to their anti-stress effect. Since this effect is counteracted by EGCG and caffeine, the ratios between these green tea components are important for the anti-stress action. In this review, we describe how green tea suppresses brain aging, through the activation of nerve cells by both EGCG and its degradation products, and the reductions in stress achieved by theanine and arginine.

Here is the link to the complete article: Green Tea Suppresses Brain Aging