More than 46,000 people observed in a study took their coffee black. Here's what happened to them

Those who drink one to two cups of black coffee a day are at a lower risk of death, a new study suggests . Black coffee and coffee with small amounts of added sugar and saturated fat were linked to a 14 per cent lower risk of all-cause mortality (death from any cause) compared to no coffee consumption, according to the study from Tufts University’s Gerald J. and Dorothy R. Friedman School of Nutrition Science and Policy. Researchers of the study, published online in May in The Journal of Nutrition , observed the drinking habits of more than 46,000 people who were 20 years old or older between 1999 and 2018. Data was used from the National Health and Nutrition Examination Survey (NHANES), which collects health and dietary information from adults in the United States. While black coffee was linked to a lower risk of death from all causes, cardiovascular disease and cancer, per the study, coffee with high amounts of added sugar and saturated fat had no such benefits. The study’s findings suggest that adding more than 5 per cent of the daily value of sugar, saturated fat, or both, to coffee diminishes the mortality benefits associated with coffee consumption. Per the U.S. Food and Drug Administration, daily values are the recommended amounts of nutrients to consume or not to exceed each day. Researchers considered a low amount of added sugar (from granulated sugar, honey, and syrup) to be around 2.5 grams per 8-ounce cup or approximately half a teaspoon of sugar. Those amounts are under 5 per cent of the daily value. They considered low saturated fat (from milk, cream, and half-and-half) to be around 1 gram per 8-ounce cup or the equivalent of five tablespoons of 2 per cent milk, 1 tablespoon of light cream, or 1 tablespoon of half-and-half. Those amounts are also under 5 per cent of the daily value. “The health benefits of coffee might be attributable to its bioactive compounds, but our results suggest that the addition of sugar and saturated fat may reduce the mortality benefits,” the study’s senior author Dr. Fang Fang Zhang said in a news release . Bioactive compounds are types of chemicals found in small amounts in plants and certain foods that promote good health, and are being studied in the prevention of cancer, heart disease, and other diseases, according to the National Cancer Institute. The amount of coffee consumed per day also played a part in how the drink could potentially be beneficial. Drinking at least one cup a day was linked to a 16 per cent lower risk of death, whereas two to three cups were associated with the “greatest reduction,” at a 17 per cent lower risk of death. However, researchers observed that drinking more than three cups of coffee per day “was not associated with additional reductions in all-cause mortality.” Many studies have aimed to show the overall health benefits of coffee consumption, including a 2017 study published in research journal The BMJ indicating that it seems “generally safe within usual levels of intake.” More recently, a 2024 study by the Endocrine Society found that drinking three cups of coffee a day might help to reduce the risk of developing more than one cardiometabolic disease. However, coffee may not be beneficial for everyone. “Individuals drinking more than five cups of coffee per day can have an increased risk of myocardial infarction (heart attack) or unstable angina (heart problem causing sudden chest pain),” according to a 2022 study published in the Journal of Personalized Medicine . Researchers at the National Institutes of Health also noted in a 2021 study that “pregnant women who consumed the caffeine equivalent of as little as half a cup of coffee a day on average had slightly smaller babies than pregnant women who did not consume caffeinated beverages.” One of the limitations of the Tufts’ study is that the information used was based on self-reported recall data, which is “subject to measurement error due to day-to-day variations in food intake.” There was also a lack of significant associations between decaffeinated coffee and all-cause mortality, which could be due to the low consumption among the population studied, per the news release. Zhang, who is the Neely Family Professor at the Friedman School, said in an email to National Post on Tuesday that the driving force behind the research was to address concerns about how coffee additions such as sugars and creams “may counterbalance coffee’s health benefits.” “Our findings confirm our hypothesis that adding high levels of added sugar and saturated fat make the benefits of coffee consumption lowering mortality risk go away,” she said. She added: “The key take away is that we need to be mindful about the amount of sugars and saturated fat that we add to coffee when we drink it.” The study is one of the first to quantify the amount of added sugar and saturated fat in coffee. It concluded: “Although our findings support the health benefits of coffee consumption, the potential negative effects of adding excessive amounts of sugar or saturated fat to coffee warrant public attention.”

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