Groene thee tegen depressies*
Uit een Japanse studie onder ruim duizend vrouwen van 70 jaar en ouder blijkt dat het drinken van
groene thee de kans op een depressie duidelijk kan doen afnemen. Ruim 54% van de deelnemende vrouwen had een milde of ernstige vorm van depressie. Zij die 4
of meer koppen groene thee per dag dronken bleken ruim 40% minder kans te hebben op een depressie dan zij die minder of geen groene thee dronken.
Green Tea Drinking in Elderly Linked to Lower Risk for Depression
More frequent consumption of green tea is associated with a lower prevalence of depressive symptoms in the community-dwelling older population, according to the results of a cross-sectional study reported in the American Journal of Clinical Nutrition.
"Green tea is reported to have various beneficial effects (e.g., anti–stress response and anti-inflammatory effects) on human health," write Hideko Takahashi, from Tohoku University Graduate School of Biomedical Engineering in Sendai, Japan, and colleagues. "Although these functions might be associated with the development and progression of depressive symptoms, no studies have investigated the relation between green tea consumption and depressive symptoms in a community-dwelling population."
The objective of the study was to evaluate the association between green tea drinking and depressive symptoms in 1058, community-dwelling, elderly Japanese subjects 70 years or older who widely consumed green tea. A self-administered questionnaire was used to determine green tea intake. The 30-item Geriatric Depression Scale was used to evaluate depressive symptoms, with a cutoff point of 11 indicating mild and severe depressive symptoms and a cutoff value of 14 indicating severe depressive symptoms. Antidepressant use was also considered to indicate depressive symptoms.
In this cohort, 34.1% had mild and severe depressive symptoms, and 20.2% had severe depressive symptoms. Compared with green tea consumption of 1 or less cup per day, odds ratios for mild and severe depressive symptoms were 0.96 for 2 to 3 cups (95% confidence interval [CI], 0.66 - 1.42) and 0.56 for 4 or more cups of green tea per day (95% CI, 0.39 - 0.81; P for trend = .001), after adjustment for confounding factors. Similar associations were seen for severe depressive symptoms.
"A more frequent consumption of green tea was associated with a lower prevalence of depressive symptoms in the community-dwelling older population," the study authors write.
Limitations of this study include cross-sectional design, preventing causal inferences; possible confounding factors; and lack of data on other psychiatric conditions, symptoms, or treatments. In addition, participants were more active and healthy than those who did not undergo the assessment, and the Geriatric Depression Scale is not designed for making a clinical diagnosis of depressive episodes.
"In the present study, higher green tea consumption (as measured by self-administered questionnaires) was significantly associated with a lower prevalence of depressive symptoms in community-dwelling elderly individuals," the study authors conclude. "This finding suggested that the consumption of green tea may have a potentially beneficial effect on the prevention of depressive symptoms. A prospective study or randomized trials are required to clarify the causality."
The Ministry of Education, Culture, Sports, Science and Technology of Japan; the Japan Atherosclerosis Prevention Fund; and the Ministry of Health, Labor, and Welfare of Japan supported this study. The study authors have disclosed no relevant financial relationships.
Am J Clin Nutr.;90:1615-1622. Abstract
Clinical Context
Drinking green tea is a common social practice in Japan, and many people believe that this tea has salutary effects on the mind and spirit. However, a previous study by Shimbo and colleagues questions this possibility. They examined the effects of green tea consumption on self-perceptions of mental health among 600 Japanese adults. Their results, which were published in the December 2005 issue of Public Health Nutrition, failed to demonstrate a significant independent effect of green tea consumption on the mental health status of men or women. However, greater caffeine intake was associated with higher rates of poor mental health among women.
The current study focuses on older adults and the effects of green tea consumption on the risk for depressive symptoms specifically. The results of this research are summarized below.
Study Highlights
· Study participants were community-dwelling adults 70 years or older in 1 city in Japan. Individuals with cognitive dysfunction were excluded from study participation.
· Participants completed a thorough history and physical examination, which included laboratory assessment of serum C-reactive protein levels and evaluation of healthy lifestyle habits.
· Depressive symptoms were assessed with the Geriatric Depression Scale. Higher scores on the scale of 0 to 30 indicate increasing depression on this scale. The cutoff scores chosen for mild and severe depression and severe depression in the current study were 11 and 14, respectively. The use of antidepressant medications was also used to define depression.
· Participants also completed a 75-item diet questionnaire, which queried their consumption of green tea, black or oolong tea, and coffee.
· The main outcome of the study was the relationship between green tea consumption and depressive symptoms. This result was adjusted to account for sociodemographic, health habit, medical, and psychological variables.
· 1058 individuals provided data for study analysis. The average age of participants was 76 years, and slightly more than half of the study cohort consisted of women.
· 286 participants drank less than 1 cup of green tea daily, whereas 284 individuals drank 2 to 3 cups per day, and 488 participants consumed 4 or more cups of green tea daily.
· Higher green tea consumption was positively associated with female sex, a history of cancer, nonsmoking status, and more social interaction with friends.
· C-reactive protein levels were unrelated to green tea consumption.
· Compared with drinking less than 1 cup of green tea per day, the adjusted odds ratio for mild and severe depression associated with drinking 2 to 3 cups per day was 0.96, a nonsignificant result. However, the same adjusted odds ratio was significant at 0.56 in comparing older adults who drank 4 or more cups of green tea daily vs those who drank less than 1 cup daily.
· The odds ratios were similar when evaluating the effects of green tea consumption on the risks for severe depression or the use of antidepressants. High levels of green tea intake were associated with significant reductions in these outcomes.
· Subgroup analysis based on participants' sex failed to alter the main study conclusion.
· There was a less-pronounced association between higher levels of consumption of black and oolong tea, and coffee as well, and reduced depressive symptoms.
Clinical Implications
· A previous study failed to demonstrate any effect of green tea consumption on the mental health of men and women. However, higher caffeine consumption was associated with worse mental health among women.
· In the current study, high levels, but not moderate levels, of green tea consumption were associated with a reduction in depressive symptoms in older
adults. (Maart 2010)
