Women after the age of 18, are almost twice as likely to struggle with depression than men. Some studies also show that rates of recurrence and worsening of depression as well as new onset depression are a vulnerability in perimenopause.
Green tea consumption and supplementation has been the subject of many research studies in areas of cardiovascular health, cancers and metabolic health and some studies now demonstrate that it has antidepressant effects.
The hypothesis for the mechanism of action of green tea’s antidepressant effects may be in its ability to reduce oxidative stress and/or inflammation. Another possibility might be an influence on hormones and the gut microbiota. The current study evaluated the lifestyle habit of long-term green tea consumption on hormones, inflammation, and depression in postmenopausal women.
A total of 386 participants met the inclusion criteria for this study with 221 women assigned to the green tea group and 165 in the control group. The tea drinking group was characterized as having at least one cup (500 mL) of green tea daily at least six days per week for over 20 years.
Depression was determined using the patient health questionnaire (PHQ-9). Blood samples were collected following an overnight fast. Estradiol, testosterone, thyrotropin (TSH), free triiodothyronine (FT3), thyroxine (FT4), and inflammatory markers were measured. The systemic immune inflammation index (SII) was used to measure inflammation.
Both groups were similar in demographic parameters and there were no significant differences between the two groups for sleep duration, blood pressure, thyroid stimulating hormone (TSH), free T3 (FT3), free T 4 (FT4), and testosterone. Green tea drinkers had lower degrees of insomnia and depression compared to non-tea drinkers. Body mass index (BMI) and SII were significantly lower in the green tea group and estradiol was significantly higher in the tea drinking group. SII and estradiol were correlated with degree of depression.
The analysis showed significant indirect effects of SII (10.3%) , estradiol (6.7%), and degree of insomnia(28.2%) on the relationship between tea drinking and degree of depression. The indirect effect of tea drinking on depression accounted for 45.2% of the total effect.
Commentary: Relying on the memory of how much green tea you have accumulated in the last 20 years seems like a big ask. In addition, not all women consumed the same amount. Questions I have: how much did each woman consume per day/per week? How concentrated was the product? What was the quality of the green tea?
While this study was of postmenopausal women, I think a more ideal group would have been perimenopausal women, since that is a vulnerable time for recurrence, worsening of chronic depression and new onset depression.
One oddity is that serum estradiol was not even tested, so it is unclear to me that they could make any association with green tea affecting estradiol levels. Mechanistically, green tea actually increases sex hormone binding globulin – and this results in a slight lowering of estradiol. The effect of green tea on depression, hormones, metabolic activity, gut microbiota, neurotransmitters and inflammation would be desirable areas of research for the future. One other thought is that green tea contains caffeine, unless it has been decaffeinated, and caffeine as we know can improve mood. Coffee companies figured that out long ago.
Reference: Wan Z, Qin X, Tian Y, Ouyang F, Wang G, Wan Q. Long-term consumption of green tea can reduce the degree of depression in postmenopausal women by increasing estradiol. Nutrients. October 2023;15(21):4514.
