Comparative Efficacy of New and Aged White Tea on Age-Related Cognitive Impairment: Insights from the Gut-Brain Axis

Long-term storage is widely believed to increase the medicinal value of white tea, but experimental support for this view remains limited. We compared new white tea (NWT) with aged white tea (AWT) in mice with D-galactose-induced cognitive impairment using chemical profiling, gut microbiota analysis, serum metabolomics, biochemical assays and behavioral tests. Compared with model mice, AWT and NWT increased spontaneous alternation by 115% and 159% and shortened escape latency by 61% and 57%, respectively. Brain superoxide dismutase (SOD) activity increased by 64% with AWT and 100% with NWT, whereas malondialdehyde (MDA) levels decreased by 51% and 79%. AWT also increased the abundance of the Lachnospiraceae NK4A136 group and lowered serum lipopolysaccharide (LPS) by approximately 36%. The abundance of this bacterial group correlated negatively with brain MDA and positively with SOD activity. NWT contained more catechin monomers and showed larger changes in brain antioxidant markers and several measures of spatial memory. In contrast, AWT contained more oxidized and polymerized catechin products, accompanied by more marked changes in gut microbiota and circulating LPS. Both treatments increased serum histidine and brain histamine, suggesting a shared association with histidine and histamine metabolism. Together, coordinated changes in gut bacteria, circulating LPS and histidine, brain histamine and oxidative status, and behavior support a response associated with the gut-brain axis. These findings suggest that storage alters the biological profile of white tea rather than simply increasing its activity.