According to a new study published in March 2013, green tea and coffee intake decreases the risk of depression. An estimated 14.8 million American adults—or 6.7 percent—are affected by depression in a given year.
The subjects included 537 adults between 20-68 years of age. The subjects completed a dietary questionnaire to evaluate green tea and coffee intake, and researchers calculated the caffeine intake from the data collected. The researchers assessed depression symptoms using the Center for Epidemiologic Studies Depression Scale.
The investigators found that coffee or green tea consumption was associated with a lower likelihood of depressive symptoms. More specifically, the subjects who drank four or more cups of green tea per day had a 51 percent decrease in the likelihood of having depressive symptoms compared to the subjects that drank one cup of green tea or less per day.
Additionally, the subjects who drank two or more cups of coffee per day had a 39 percent decrease in the likelihood of developing depressive symptoms compared to the subjects that drank less than one cup of coffee per day. Furthermore, the researchers determined that the subjects with the highest caffeine consumption had a 43 percent decrease in the likelihood of having depressive symptoms compared to the subjects with the lowest caffeine intake.
The investigators concluded, "Results suggest that higher consumption of green tea, coffee and caffeine may confer protection against depression."