A large “umbrella” review of 218 studies on coffee and health found that people who drink 3 to 4 cups a day are at lower risk of a range of diseases and conditions, says a study in The BMJ. The umbrella review combined the results of 218 meta-analyses, each of which combined findings from multiple studies. These “studies of studies” included 17 with randomized clinical trials, which—compared to observational studies—produce stronger evidence that coffee may directly reduce the risk of certain diseases.
The umbrella review found that coffee drinking is associated with lower risk of cancer and cardiovascular disease or death from any cause. That’s consistent with two large observational studies published in August 2017 in the Annals of Internal Medicine. (See October 2017 issue of HNL.) The latest review identified some potential harms associated with drinking 3 to 4 cups a day, namely small increased risks for low birth weight, premature birth and miscarriage, as well as a slightly higher risk of fracture in women.
Collectively, authors say, research has shown that coffee consumption is “more likely to benefit health than harm.” But to establish coffee as effective for preventing diseases, more clinical trials are needed. But the authors caution that women at risk of fracture, or pregnant or could become pregnant, should probably be excluded from such trials.