Written by Taylor Woosley, Staff Writer. Findings of the study show that, compared to non-green tea drinkers, participants with long-term green tea consumption had improved sleep, increased estradiol, a lower inflammatory index, and reduced depression levels.
Statistics show that there is an increasing number of postmenopausal women globally, and the number is expected to reach 1.1 billion by 20251. The risk of depression has been reported to increase in women during the postmenopausal stages and the development of depression symptoms is approximately 1.8 and 2.0 times higher in the menopausal and postmenopausal stages compared to pre-menopausal women2. Differences in depression levels among pre- and postmenopausal women may be related to differences in inflammation, with various studies finding higher levels of inflammatory biomarkers in postmenopausal women3.
Green tea, one of the most popular beverages consumed around the world, is suggested to exert protective effects against depression4. The major components of green tea are EGCG, caffeine, theanine, and arginine, which are shown to possess potent antioxidant and anti-inflammatory activities5. The catechins in green tea have been shown to increase serum levels of noradrenaline and dopamine, which are believed to play a major role in combatting depression6.
Wan et al. conducted a study to investigate if the effects of long-term green tea consumption can improve endocrine and inflammation in postmenopausal women and reduce depression risk. The study took place in a tea-growing village where a large majority of the population started drinking green tea in adulthood. Subjects completed questionnaires with information regarding basic sociodemographic information, green tea consumption, sleep quality, and depression incidence. Participants in the tea drinking group were defined as drinking at least 1 cup (500 mL) of green tea 6-7 days per week for at least 20 years. Subjects who barely or never drank tea were placed in the control group.
Sleep patterns were assessed using the insomnia severity index scale. Depression severity was analyzed using the PHQ-9 (Patient Health Questionnaire). Fasted blood samples were obtained to measure estradiol, testosterone, TSH, FT3, FT4, and inflammation markers via ELISA. The Systemic Immune Inflammation Index was utilized to assess inflammation levels. The Chi-square test and non-parametric tests were used to measure differences between groups.
386 participants completed the study and 57.3% were long-term green tea drinkers. No significant differences were noted regarding differences in sleep duration, blood pressure, TSH, FT3, FT4, and testosterone between the two groups. There were significant differences in insomnia degree (p = 0.003), degree of depression (p = 0.002), BMI (p < 0.001), SII (p = 0.033) and estradiol (p < 0.001) between groups. Significant findings of the study are as follows:
- Results of an ordered logistic regression model shows that participants in the green tea group had a lower degree of depression (p = 0.038). Furthermore, the concentration of SII (p = 0.003) and estradiol (p = 0.029) were also highly correlated with depression degree.
- A significant indirect effect was noted between SII, estradiol, and insomnia on the relationship between green tea consumption and the degree of depression. The total indirect effect of green tea consumption on depression degree was -0.094 (p < 0.001), accounting for 45.2% of the total effect.
Results of the study suggest that long term green tea consumption is associated with a reduced degree of depression. These findings may be due to green tea’s effects on increasing estradiol, improving insomnia, and decreasing inflammation. Study limitations include the lack of information regarding the frequency and concentration of the green tea consumed and the lack of generalizability of results due to subjects being postmenopausal women.
Source: Wan, Zhenyu, Xucong Qin, Yuling Tian, Fangcheng Ouyang, Gaohua Wang, and Qirong Wan. “Long-Term Consumption of Green Tea Can Reduce the Degree of Depression in Postmenopausal Women by Increasing Estradiol.” Nutrients 15, no. 21 (2023): 4514.
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Posted December 12, 2023.
Taylor Woosley studied biology at Purdue University before becoming a 2016 graduate of Columbia College Chicago with a major in Writing. She currently resides in Glen Ellyn, IL.
References:
- Hashemian SS, Masom-Alipour S, Najimi A. Improving menopausal symptoms and reducing depression in postmenopausal women: Effectiveness of transferring experiences in group education. J Educ Health Promot. 2020;9:318. doi:10.4103/jehp.jehp_342_20
- Wu YT, Huang WY, Kor CT, et al. Relationships between depression and anxiety symptoms and adipocyte-derived proteins in postmenopausal women. PLoS One. 2021;16(3):e0248314. doi:10.1371/journal.pone.0248314
- Azarmanesh D, Bertone-Johnson ER, Pearlman J, Liu Z, Carbone ET. Association of the Dietary Inflammatory Index with Depressive Symptoms among Pre- and Post-Menopausal Women: Findings from the National Health and Nutrition Examination Survey (NHANES) 2005-2010. Nutrients. May 9 2022;14(9)doi:10.3390/nu14091980
- Nanri A, Eguchi M, Kochi T, Kabe I, Mizoue T. Green Tea Consumption and Depressive Symptoms among Japanese Workers: The Furukawa Nutrition and Health Study. Nutrients. Dec 30 2021;14(1)doi:10.3390/nu14010167
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- Yaegashi A, Kimura T, Hirata T, Tamakoshi A. Green Tea Consumption and Risk of Depression Symptoms: A Systematic Review and Meta-Analysis of Observational Studies. J Nutr Sci Vitaminol (Tokyo). 2022;68(3):155-161. doi:10.3177/jnsv.68.155
