Drinking moderate amounts of coffee—about three or four cups a day—is more likely to benefit our health than harm it, our latest research shows. This is important to know because around the world over two billion cups of coffee are consumed every day.
Earlier studies have suggested beneficial links between coffee drinking and liver disease. Our research group has an interest in liver conditions. As such, we had previously conducted two meta-analyses, one looking for links between coffee drinking and cirrhosis and another for coffee drinking and cancer of the liver. We found that there was a lower risk of both conditions in people who drank more coffee.
Most of the evidence, however, is from observational studies, which can only find probable associations but can’t prove cause and effect. To overcome these limitations, we plan to conduct a randomized controlled trial in patients with non-alcoholic fatty liver disease to see if coffee works as a treatment to reduce the risk of the disease progressing.
But before we can start giving coffee to patients, we needed to know whether coffee drinking had any recognized harms, so we decided to conduct an umbrella review to capture as much important information about coffee drinking and health as we could. Umbrella reviews combine previous meta-analyses and give a high level summary of research findings.
Overall, our umbrella analysis showed that drinking coffee is more often linked with benefits than harms. For some conditions, the largest benefit appeared to be associated with drinking three to four cups of coffee each day. This included lower risk of death from any causes, or getting heart disease. Drinking coffee beyond these amounts was not associated with harm, but the benefits were less pronounced.
Drinking coffee was also associated with a lower risk of developing type 2 diabetes, metabolic syndrome, gallstones, renal stones and gout. We also found that it was associated with a lower risk of getting some types of cancer, Parkinson’s disease, depression and Alzheimer’s disease. But liver disease stood out as having the greatest benefit compared with other conditions.
Read more at Quartz.