Women who drink two or more cups of coffee a day are less likely to get depressed, research suggests. The finding published in the Archives of Internal Medicine¹, come from a study of more than 50,000 U.S. female nurses. Researchers from the Harvard School of Public Health stressed that theirs was an observational study, and can only suggest the possibility of coffee’s protective effect, rather that prove that it reduces depression risk. M. Lucas and team set out to determine whether the consumption of coffee or some drinks containing caffeine might be linked to depression risk.
They gathered data on 50,737 women, average age 63 years; none of them had depression when the study began. They had all participated in the Nurses’ Health Study. They were prospectively followed up until June 2006. Questionnaires had asked them what their caffeine consumption was from 1980 to 2004. The researchers had data on how often they consumed caffeinated and non-caffeinated coffee, non-herbal tea, caffeinated soft drinks (sugared or low calorie), all types of caffeine-free soft drinks, and chocolate during a twelve month period before filling in each questionnaire. In this study, depression was defined as having a diagnosis of clinical depression and being prescribed regular antidepressants during the previous two years.
Below are some highlighted data from their findings:
- Women who consumed two to three cups of caffeinated coffee per day were 15% less likely to develop depression compared to those who drank a maximum of one cup of caffeinated coffee per week
- Women who drank at least 4 cups per day had a 20% lower risk than the maximum 1 cup per week females
- Those who consumed at least 550mg per day of caffeine had a 20% lower risk of developing depression compared to the women whose daily consumption was 100mg or less per day
- The consumption of decaffeinated coffee had no impact on depression risk
The authors wrote: “In this large prospective cohort of older women free of clinical depression or severe depressive symptoms at baseline, risk of depression decreased in a dose-dependent manner with increasing consumption of caffeinated coffee.” They added: “(this observational study) cannot prove that caffeine or caffeinated coffee reduces the risk of depression but only suggests the possibility of such a protective effect.”¹M Lucas et al, 2011. Coffee, Caffeine, and Risk of Depression Among Women, Archives of Internal Medicine, 171 (17). Source