“Unlike previous investigations, we were able to assess association of consumption of caffeinated and non-caffeinated beverages, and we identify caffeine as the most likely candidate of any putative protective effect of coffee,” said lead researcher Michel Lucas, research fellow in the Department of Nutrition at HSPH.
But a caveat: The study authors don’t go as far as to recommend that depressed people increase caffeine consumption, “because most individuals adjust their caffeine intake to an optimal level for them and an increase could result in unpleasant side effects.”
The author added: “Overall, our results suggest that there is little further benefit for consumption above two to three cups/day or 400 mg of caffeine/day.”
A study by Harvard in 2011 reported those who drink two or three cups a day have a 15 per cent lower incidence of depression than those who rarely do so.
Earlier studies and reports have concluded the opposite, writing, “Caffeine tends to increase the release of insulin in the blood, and insulin lowers the blood sugar level. When you have low blood sugar levels, you begin to feel less sure of yourself, and have low energy levels, which can lead to the blues or depression.”
On the flip side, depression is more common in people who drink diet soda and other artificially-sweetened drinks, as a Digital Journal report explains.