Researchers surveyed 171,616 UK participants up to five times over the course of a year about their lifestyle, including their coffee drinking habits. The scientists then looked up death certificates to see who had died, on average, seven years later.
Participants ranged in age from 37 to 73 years and said they had no cardiovascular disease or cancer at the time of the survey.
The results showed that for people who drank a moderate amount of coffee, defined as 1.5 to 3.5 cups per day, those who sweetened their coffee had about a 30% lower risk of death than non-coffee drinkers, according to Dr . Christina Wee, associate professor of medicine at Harvard Medical School, who was not involved in the study. She is also Associate Editor of the Annals of Internal Medicine.
Unsweetened coffee drinkers have between 16% and 29% lower risk of death compared to non-coffee drinkers, she added.
Results were adjusted for sociodemographic, lifestyle, and clinical factors to eliminate their impact on results. For example, the research team asked questions about smoking levels, amount of physical activity, level of education and dietary habits, Wee said.
There’s a limit to the researchers’ adjustments because they didn’t ask about other factors that might affect the results, such as income level and occupation, she said.
Watch out for added sugar
If you’re drinking sugar-laden lattes and caramel macchiatos, you’re out of luck.
The average coffee drinker who reported sweetening their coffee put in an average of 1 teaspoon, according to the study.
“If you add just about 1 teaspoon of sugar to your coffee, the benefits of coffee that we believe are there aren’t completely negated by that 1 teaspoon,” Wee said.
The results were less clear for people who used artificial sweeteners in coffee, so the researchers couldn’t draw any conclusions about people who preferred sugar substitutes.
“Based on this study, clinicians can tell their patients that while most coffee drinkers do not need to eliminate the beverage from their diet, they should be cautious about higher-calorie specialty coffees,” wrote the study’s lead author, Dr. Dan Liu, in an email. She is from the Department of Epidemiology at Southern Medical University in Guangzhou, China.
How does coffee affect the body?
Coffee also has different health profiles depending on how it’s made, said Gunter Kuhnle, a professor of nutrition and food science at the University of Reading in the UK. He was not involved in the study.
Some species contain phenolic compounds that are thought to be beneficial, he said.
Unroasted green coffee beans contain high levels of phenolic compounds, but the bad flavor when brewed causes people to roast them. Depending on the degree of roasting, some of the phenolic compounds can be broken down.
And depending on how you brew it, coffee can be high in diterpenes, which are chemical compounds that can increase your risk of cardiovascular disease, Kuhnle said.
Mocha and espresso coffees contained moderate amounts of diterpenes, while instant or filtration coffees had the least.