green tea Archives | Misha Blagosklonny

In 2019, researchers conducted the first study to explore the effects of habitual tea drinking on system-level brain networks.

Figure 3. Brain regions exhibiting significant differences in structural nodal efficiency between the tea drinking group and the non-tea drinking group at the significance level of 0.01 (uncorrected) statistical evaluated by a permutation test.

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After water, tea is the most popular beverage in the world. While many people enjoy tea for the flavor, aroma and caffeine boost, research suggests that there may be another reason to regularly drink this beverage: its effects on the brain. In 2019, researchers from Wuyi University, University of Essex, University of Cambridge, and the National University of Singapore conducted the first study exploring the effects of tea on system-level brain networks. Their paper was published in Aging (Aging-US) Volume 11, Issue 11, and entitled, “Habitual tea drinking modulates brain efficiency: evidence from brain connectivity evaluation.”

“In this study, we comprehensively explored brain connectivity with both global and regional metrics derived from structural and functional imaging to unveil putative differential connectivity organizations between tea drinking group and non-tea drinking group.”

The Study

The subjects enrolled in this study were older adults (mean ≈ 70 years old) from residential communities in Singapore, without conditions or terminal illnesses (see Materials and Methods). Researchers initially recruited 93 participants, however, only 36 total participants (male = 6; female = 30) remained after adjusting for the strict study inclusion criteria. Researchers classified the remaining participants as “non-tea drinkers” or “tea drinkers” using complex composite test scores. The composite score included self-reports of multiple decades of weekly green tea, oolong tea, black tea, and coffee intake (see Materials and Methods). After screening, 15 participants were assigned to the tea-drinking group and 21 were assigned to the non-tea drinking group. (Coffee intake did not differ significantly between the two groups.)

Next, structural brain connectivity was compared between tea drinkers and non-tea drinkers. All 36 participants underwent MRI brain scans and both functional and structural networks were investigated from global and regional perspectives. The researchers found that participants in the tea-drinking group had more efficient structural organization. However, tea did not seem to have a significantly beneficial effect on global functional organization. As a result of tea drinking, hemispheric asymmetry in the structural connectivity network was observed, although it was not observed in the functional connectivity network.

“In addition, functional connectivity strength within the default mode network (DMN) was greater for the tea-drinking group, and coexistence of increasing and decreasing connective strengths was observed in the structural connectivity of the DMN.”

Conclusion

The researchers found that tea drinkers had more efficient brain structure organization than non-tea drinkers. Studies have previously demonstrated that tea drinkers are less likely to develop dementia, and tea consumption has also been linked with better cognitive performance. The researchers note that these effects are due to tea’s contents of caffeine, L-theanine and polyphenols (catechins). Polyphenols are compounds found in plants, including tea leaves, and may help protect against oxidative damage. Previous studies have shown that tea polyphenols can cross the blood-brain barrier and may help improve brain function.

While this study’s findings suggest that habitual tea drinking leads to better brain connectivity and efficiency in old age, the researchers were forthcoming about the limitations of their study. The sample size was limited and other substances, behaviors, habits, and environmental factors may have impacted the outcome of the study.

“Our study offers the first evidence of the positive contribution of tea drinking to brain structure and suggests a protective effect on age-related decline in brain organisation.”

Click here to read the full research paper published by Aging (Aging-US).

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The mechanisms and pathways involved in the health and aging benefits conveyed by green tea were investigated in C. elegans.

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Boiled or iced with water or milk, blended in smoothies, condensed into shots or even baked into pastries—humans are infatuated with green tea. Today, green tea is one of the most widely consumed beverages in the world. Molecules found in this plant, named catechins, are known to have numerous evidence-based health benefits, including weight loss and age delaying properties. However, the mechanism by which these effects take place have yet to be fully elucidated.

“The popularity of green tea makes it crucial to study its impact on health and aging.”

Researchers from Friedrich Schiller University Jena, Huazhong Agricultural University, ETH Zurich, and the Medical University of Graz investigated green tea catechins and their effects in roundworms, known as Caenorhabditis elegans (C. elegans), and isolated rodent mitochondria. Their trending paper was published in October of 2021 by Aging (Aging-US), and entitled, “Green tea catechins EGCG and ECG enhance the fitness and lifespan of Caenorhabditis elegans by complex I inhibition.”

“We have designed the current study to investigate the impact and to unveil the target of the most abundant green tea catechins, epigallocatechin gallate (EGCG) and epicatechin gallate (ECG).”

The Study

In this study, the researchers focused on testing two of the most common green tea catechins, epigallocatechin gallate (EGCG) and epicatechin gallate (ECG), in isolated mitochondria from murine liver and C. elegans. C. elegans are approximately one millimeter long nematodes, or roundworms, and have been used in a variety of biomedical studies. The reason C. elegans were chosen for this study is likely due to the fact that many genes in C. elegans have functional counterparts in humans. (C. elegans also have the ability to “smell” cancer.)

Over the course of 24 hours or seven days, C. elegans and rodent mitochondria were treated with 2.5 μM of EGCG and/or ECG compounds. To analyze the green tea catechins’ effects on cellular metabolism, reactive oxygen species (ROS) homeostasis, stress resistance, physical exercise capacity, health- and lifespan, and on the underlying signaling pathways, the researchers conducted lifespan analyses, locomotion assay, paraquat stress resistance assay, basal oxygen consumption rate, ROS quantification, glucose oxidation assay, ATP quantification, activity assays for catalase and superoxide dismutase, fat content analysis, quantification of complex I activity in mitochondria, quantification of oxygen consumption rate in mitochondria, and statistical analyses.

“We conclude that applying the green tea catechins EGCG and ECG at a low dose extends the lifespan of C. elegans via inducing a mitohormetic response.”

They found that the catechins hindered mitochondrial respiration in C. elegans after 6–12 hours, the activity of complex I in isolated rodent mitochondria and temporarily increased ROS levels. Then, after 24 hours and through adaptive responses, catechins reduced fat content, enhanced ROS defense and, in the long term, improved healthspan in C. elegans.

Conclusion

Mechanisms and pathways observed to be involved in this process of C. elegans fitness and lifespan extension by green tea were further described in the paper. The researchers note that additional studies will be required to determine the best timing and dosage for administering catechins. They also acknowledge that the low bioavailability of green tea catechins may limit the lifespan extending effects of green tea in humans, despite the promising effects demonstrated in C. elegans.

“Despite the promising results obtained in animal experiments, the low bioavailability of EGCG [7] still raises the question of whether green tea catechins can reliably provoke beneficial effects in humans. Consequently, additional efforts might be needed to identify complex I inhibitors with increased bioavailability.”

Click here to read the full priority research paper published by Aging (Aging-US).

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