In a cohort study published Monday in the Annals of Internal Medicine, researchers found that individuals who drank a moderate amount of coffee, either unsweetened or sweetened with about a teaspoon of sugar, were roughly 30% less likely to die during a seven-year period than non-coffee drinkers.

Study details and key findings

For the study, researchers from Southern Medical University in Guangzhou, China, analyzed behavioral data from 171,616 individuals enrolled in the U.K. Biobank cohort, an ongoing study of health information in the United Kingdom.

On average, participants were 55.6 years old, with no signs of cardiovascular disease or cancer when the study began.

The researchers invited participants to complete an online 24-hour dietary recall questionnaire five times over the course of a year from April 2009 to June 2012. The questionnaire asked participants how often they drank coffee and how many teaspoons of sweetener, if any, they added. Researchers gathered mortality data from death certificates through Feb. 25, 2018.

Overall, around 76% of participants were coffee drinkers. Most participants (55.4%) said they drank unsweetened coffee, while 14.3% said they added an average of one teaspoon of sugar to their coffee, and 6.1% said they used artificial sweeteners.

Over the median follow-up period of seven years, 3,177 participants died, with a total of 1,725 cancer deaths and 628 cardiovascular deaths.

Participants who drank any amount of unsweetened coffee were less likely to die from any cause during the seven-year follow-up period than people who didn't drink coffee.

In particular, participants who drank 1.5 to 3.5 cups of coffee each day, either unsweetened or sweetened with sugar, were between 29% and 31% less likely to die than those who didn't drink coffee. Notably, results were "less consistent" among those who used artificial sweeteners in their coffee, according to MedPage Today.

Commentary

According to Chen Mao of Southern Medical University, and co-authors, there were a few limitations with the study, including how participant data was collected at least 10 years ago in a country where tea is just as popular as coffee.

The benefits of coffee are regularly debated, noted Christina Wee, deputy editor of Annals of Internal Medicine, and this study doesn't answer some of the key questions surrounding the debate.

"The average dose of added sugar per cup of sweetened coffee was only a little over a teaspoon, or about 4 grams," Wee said. "This is a far cry from the 15 grams of sugar in an 8-ounce cup of caramel macchiato at a popular U.S. coffee chain."

"The authors defined moderate levels of coffee drinking as drinking one and a half to three and a half cups of coffee," she noted. "They found that drinking moderate levels of coffee regularly was associated with a lower risk of dying from any cause, dying from cancer, and dying from heart disease."

"The lower risk of dying associated with moderate levels of coffee drinking was true regardless of whether you drank decaffeinated coffee, instant coffee, or ground coffee," Wee added.

"Although we cannot definitively conclude that drinking coffee reduces mortality risk, the totality of the evidence does not suggest a need for most coffee drinkers – particularly those who drink it with no or modest amounts of sugar – to eliminate coffee," Wee wrote.

"So drink up," she added, "but it would be prudent to avoid too many caramel macchiatos while more evidence brews." (Reed, Axios, 5/31; George, MedPage Today, 5/30)