Green Tea: A Boost For Cognitive Function

In discussions with my patients at the Kahn Center for Cardiac Longevity, a routine question is asking about memory and cognitive function. It is surprising how often the response is one of concern over failing memory. Simple approaches to enhancing cognitive function are needed. 

Roasted green tea, also known as hojicha, is a type of Japanese green tea roasted over charcoal to give the tea a unique smoky flavor and dark brown color. Previous research has highlighted the cognitive benefits of green tea consumption. 

Now, a new study has examined the impact of even small amounts of green tea over a short period and the results are encouraging. 

STUDY

Participants included 20 healthy young men who performed a mental arithmetic task while 11 physiological responses were measured. The experiments were conducted twice under different beverage consumption conditions on separate days. The mental arithmetic task was executed six times in 1 day; participants ingested hot water, green tea, or roasted green tea (hojicha) before each task. Several subjective assessments: including subjective fatigue, stress, mental workload, and flow were evaluated after each task in addition to R–R intervals and heart rate variability.

By scrutinizing various indicators, we found that aromatic stimulation of Japanese tea beverages has the potential to induce positive effects, enhance mental task performance, promote refreshment, and alleviate feelings of fatigue.

These results suggest that drinking green tea or roasted green tea may have helped moderate the participants’ physiological stress responses.

Aromatic compounds present in green tea, known to have relaxation effects, appeared to play a significant role in these positive outcomes.

“By scrutinizing various indicators, we found that aromatic stimulation of Japanese tea beverages has the potential to induce positive effects, enhance mental task performance, promote refreshment, and alleviate feelings of fatigue,” wrote the study authors.

Throughout all sessions, task performance was significantly higher with tea consumption than water.

Only the roasted green tea seemed to have anti-fatigue properties despite being lower in caffeine content than regular green tea.

Particularly in the sessions where roasted tea was used, a higher number of task repetitions also led to a greater improvement in response rate and task performance.

Importantly, these benefits were observed with small amounts of tea and within a short time frame, which aligns with typical daily tea consumption habits.

IMPLICATIONS

While hojicha green tea may not be a household word, it is available at stores and online vendors in loose and bag versions. 

An aging expert at Rush University said, "Considering that green tea is abundant in flavan-3-ols — comprising multiple catechins among other flavonoids — and flavanols both of which have been linked to enhanced brain health, it is not only reasonable but also advisable to include green tea in one’s diet.”