Among more than 170,000 people in the United Kingdom, those who drank about two to four cups of coffee a day, with or without sugar, had a lower rate of death than those who didn’t drink coffee, reported lead author Dan Liu, MD, of the department of epidemiology at Southern Medical University, Guangzhou, China.
“Previous observational studies have suggested an association between coffee intake and reduced risk for death, but they did not distinguish between coffee consumed with sugar or artificial sweeteners and coffee consumed without,” Dr. Liu, who is also of the department of public health and preventive medicine, Jinan University, Guangzhou, China, and colleagues wrote in Annals of Internal Medicine.
To learn more, the investigators turned to the UK Biobank, which recruited approximately half a million participants in the United Kingdom between 2006 and 2010 to undergo a variety of questionnaires, interviews, physical measurements, and medical tests. Out of this group, 171,616 participants completed at least one dietary questionnaire and met the criteria for the present study, including lack of cancer or cardiovascular disease upon enrollment.
Results from these questionnaires showed that 55.4% of participants drank coffee without any sweetener, 14.3% drank coffee with sugar, 6.1% drank coffee with artificial sweetener, and 24.2% did not drink coffee at all. Coffee drinkers were further sorted into groups based on how many cups of coffee they drank per day.
Coffee drinkers were significantly less likely to die from any cause
Over the course of about 7 years, 3,177 of the participants died, including 1,725 who died from cancer and 628 who died from cardiovascular disease.
After accounting for other factors that might impact risk of death, like lifestyle choices, the investigators found that coffee drinkers were significantly less likely to die from any cause, cardiovascular disease, or cancer, than those who didn’t drink coffee at all. This benefit was observed across types of coffee, including ground, instant, and decaffeinated varieties. The protective effects of coffee were most apparent in people who drank about two to four cups a day, among whom death was about 30% less likely, regardless of whether they added sugar to their coffee or not. Individuals who drank coffee with artificial sweetener did not live significantly longer than those who drank no coffee at all; however, the investigators suggested that this result may have been skewed by higher rates of negative health factors, such as obesity and hypertension, in the artificial sweetener group.
Dr. Liu and colleagues noted that their findings align with previous studies linking coffee consumption with survival. Like those other studies, the present data revealed a “U-shaped” benefit curve, in which moderate coffee consumption was associated with longer life, whereas low or no consumption and high consumption were not.
Experts caution against drinking sweetened beverages despite new findings
Although the present findings suggested that adding sugar did not eliminate the health benefits of coffee, Dr. Liu and colleagues still cautioned against sweetened beverages, citing widely known associations between sugar consumption and poor health.
In an accompanying editorial, Christina C. Wee, MD, MPH, deputy editor of Annals of Internal Medicine, pointed out a key detail from the data: the amount of sugar added to coffee in the U.K. study may be dwarfed by the amount consumed by some coffee drinkers across the pond.
“The average dose of added sugar per cup of sweetened coffee [in the study] was only a little over a teaspoon, or about 4 grams,” Dr. Wee wrote. “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.”
Still, Dr. Wee, an associate professor of medicine at Harvard Medical School, Boston, and director of the obesity research program in the division of general medicine at Beth Israel Deaconess Medical Center, Boston, suggested that your typical coffee drinker can feel safe in their daily habit.
“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,” she wrote. “So drink up – but it would be prudent to avoid too many caramel macchiatos while more evidence brews.”
Estefanía Toledo, MD, MPH, PhD, of the department of preventive medicine and public health at the University of Navarra, Pamplona, Spain, offered a similar takeaway.
“For those who enjoy drinking coffee, are not pregnant or lactating, and do not have special health conditions, coffee consumption could be considered part of a healthy lifestyle,” Dr. Toledo said in a written comment. “I would recommend adding as little sugar as possible to coffee until more evidence has been accrued.”
Dr. Toledo, who previously published a study showing a link between coffee and extended survival, noted that moderate coffee consumption has “repeatedly” been associated with lower rates of “several chronic diseases” and death, but there still isn’t enough evidence to recommend coffee for those who don’t already drink it.
More long-term research is needed, Dr. Toledo said, ideally with studies comparing changes in coffee consumption and health outcomes over time. These may not be forthcoming, however, as such trials are “not easy and feasible to conduct.”
David Kao, MD, assistant professor of medicine-cardiology and medical director of the school of medicine at the University of Colorado at Denver, Aurora, said that the study conducted by Dr. Liu and colleagues is a “very well-executed analysis” that strengthens our confidence in the safety of long-term coffee consumption, even for patients with heart disease.
Dr. Kao, who recently published an analysis showing that higher coffee intake is associated with a lower risk of heart failure, refrained from advising anyone to up their coffee quota.
“I remain cautious about stating too strongly that people should increase coffee intake purely to improve survival,” Dr. Kao said in a written comment. “That said, it does not appear harmful to increase it some, until you drink consistently more than six to seven cups per day.”
The study was supported by the National Natural Science Foundation of China, the Young Elite Scientist Sponsorship Program by CAST, the Guangdong Basic and Applied Basic Research Foundation, and others. Dr. Toledo and Dr. Kao disclosed no relevant conflicts of interest.