How much coffee is safe to drink?

  Published to Latest News on May 10, 2018

Coffee is one of the most commonly consumed beverages worldwide. Over recent years it has increasingly won the approval of researchers with studies suggesting coffee may have some beneficial effects on health. An analysis, published in November in the BMJ  http://www.bmj.com/content/359/bmj.j5024 scanned nearly 220 studies on coffee and found that overall coffee drinkers may enjoy health benefits over people who don’t drink it.

Some of the reviewed studies linked coffee drinking to lower rates of heart disease, Parkinson’s and Alzheimer’s disease. The researchers from the University of Southampton  learned that people who drank coffee were 17% less likely to die early during the study period from any cause, 19% less likely to die of heart disease and 18% less likely to develop cancer, compared to people who didn’t drink coffee. However, it was noted that the studies each had different designs and not all of them may have adjusted for potential confounding effects that could skew the connection between coffee and health outcomes. Coffee drinkers, for example, were generally found to be more likely to smoke more than non-drinkers.

Dr. Eliseo Guallar, professor of epidemiology and medicine at Johns Hopkins Bloomberg School of Public Health, who wrote an editorial accompanying the study, said “I think now we can be reasonably reassured that overall, coffee drinking is a safe habit”.

Other studies have tried to determine which ingredients in coffee contribute to its health benefits. Those might include antioxidants and anti-inflammatory compounds, concluding coffee may have protective effects against cancer, heart conditions and neurodegenerative disorders, as well as the risk of liver diseases such as cirrhosis.

The University of Southampton group found the most significant benefit occurred among people who had a daily intake of around three to four cups of coffee. While the researchers concluded the results support moderate coffee drinking, they say the findings don’t go far enough to prompt anyone to change their coffee-drinking habits in the hopes of improving their health. For example, the study did not confirm that people who don’t currently drink coffee should start adding it in order to lower their risk of developing the chronic conditions studied. Neither was there evidence to support the idea that current coffee drinkers should drink even more coffee to enhance whatever benefits they might be receiving. Too much coffee, the data suggest, starts to bend the benefit curve back down.

The study concluded that whilst future randomised controlled trials are needed, coffee drinking seems generally safe within usual patterns of consumption, namely three or four cups daily. The only negative health effects the review determined were among women, who were at slightly higher risk of developing fractures if they drank more coffee, and pregnant women. The study found that pregnant women who drank more coffee tended to have higher rates of miscarriage, more premature births and more babies born with low birth weight than women who drank less coffee.

Tags: health