The study, which could not draw conclusions to artificial sweetener use, suggests those who drank 1.5-3.5 cups per day were 29-31% less likely to die than those who did not drink coffee.
“It appears that those who consumed unsweetened coffee did drink slightly more of other drinks with sweeteners (such as diet soft drinks) than those who added sweeteners to their coffee, which makes it harder to fully interpret the effect of sweeteners in this study,” says Dr Duane Mellor Senior Teaching Fellow, Aston Medical School, Aston University, who was not involved in the study.
“The suggestion that this may be due to antioxidant effects, as suggested in the journal is not completely correct.
“Although these effects have been seen in laboratory studies in test tubes, the available does of these compounds in 1-3.5 cups of coffee would not be enough to have that effect in a human.”
While it is possible that there may be a biological effect of some of the compounds in coffee, Dr Mellor pointed to interactions with the gut microbiome or by regulating enzyme activity in the liver, as the most likely explanation.
The team from Southern Medical University in Guangzhou, China drew from UK Biobank study data that followed more than 171,000 UK participants.
These subjects were questioned on their coffee consumption habits particularly consumption of sugar-sweetened, artificially sweetened, and unsweetened coffee and the link to all-cause and cause-specific mortality.
The authors found that during the seven-year follow up period, participants who drank any amount of unsweetened coffee were 16–21% less likely to die than participants who did not drink coffee.
They also found that participants who drank 1.5 to 3.5 daily cups of coffee sweetened with sugar were 29-31% less likely to die than participants who did not drink coffee.
The authors noted that adults who drank sugar-sweetened coffee added only about one teaspoon of sugar per cup of coffee on average. Results were inconclusive for participants who used artificial sweeteners in their coffee.
In an editorial written by the Annals of Internal Medicine editors it was acknowledged that coffee has qualities that could make health benefits possible.
However, variables including socioeconomic status, diet, and other lifestyle factors could impact findings.
They add: “The average amount of daily sugar per cup of coffee recorded in this analysis is much lower than specialty drinks at popular coffee chain restaurants.
“Many coffee consumers may drink it in place of other beverages that make comparisons to non-drinkers more difficult.
“Based on this data, clinicians can tell their patients that there is no need for most coffee drinkers to eliminate the beverage from their diet but to be cautious about higher calorie specialty coffees.”
Dr Annette Creedon, Nutrition Manager at the British Nutrition Foundation adds that the coffee consumption habits reported in the study are almost ten years old.
Coffee drinking habits may have changed since then, not only in relation to the types of coffee but also the average volume of coffee consumed.
This, she said may be relevant in terms of health and all-cause mortality associated with coffee drinking.
“However, Liu and colleagues acknowledge that respondents may have underestimated the volume of coffee they consumed.
“Other dietary factors that weren’t reported on may have also changed over the study period and this could have had an influence on the outcomes of the study,” she adds.
“It should be noted that the amount of added sugar reported in this study was very low and may not reflect the amount of sugar that people typically add to their coffee.”
Source: Annals of Internal Medicine
Published online: doi.org/10.7326/M21-2977
“Association of Sugar-Sweetened, Artificially Sweetened, and Unsweetened Coffee Consumption With All-Cause and Cause-Specific Mortality.”
Authors: Dan Liu et al.