Green Tea Supports Learning and Memory

The constituent in green tea, epigallocatechin gallate (EGCG), was recently shown to enhance learning and memory in rats with suboptimal blood sugar metabolism. Previous research indicates that green tea has significant antioxidant and free-radical scavenging activity as well as blood sugar balancing properties.

Healthy rats and rats with suboptimal blood sugar metabolism were supplemented with EGCG or nothing to serve as the control groups for 7 weeks. The rats received either 20 mg per kg per day or 40 mg per kg per day of EGCG. The rats were evaluated for learning and memory using several tests including the Y maze, the radial 8-arm maze and passive avoidance tasks. The rats were also assessed for markers of oxidative stress and nitrogen products in the nitric oxide system.

The study showed that the rats with suboptimal blood sugar metabolism had lower scores on the memory and learning tasks including the Y-maze, radial 8-arm maze and passive avoidance test compared to the healthy rats. Supplementation of EGCG at a dose of 40 mg per kg per day in the rats with suboptimal blood sugar metabolism resulted in mitigation of these changes. EGCG also significantly reduced levels of malondialdehyde, a marker of oxidative stress, and nitrite, which is involved in the nitric oxide system. In addition, supplementation with the nitric oxide precursor L-arginine inhibited the changes with EGCG, while the addition of the nitric oxide enzyme inhibitor 7-nitroindazole potentiated the effect of EGCG. Thus, the nitric oxide pathway may play a role in the mechanisms in which EGCG affects learning and memory.

The study authors concluded that green tea EGCG dose-dependently could enhance cognitive health in rats with suboptimal blood sugar metabolism through attenuation of oxidative stress and modulation of nitric oxide.

Reference:

Baluchnejadmojarad T, Roghani M. Chronic epigallocatechin-3-gallate ameliorates learning and memory deficits in diabetic rats via modulation of nitric oxide and oxidative stress. Behav Brain Res. 2011 Jun 14. Published Online Ahead of Print.