“We observed an inverse association for coffee drinking with mortality, including those drinking filtered, instant, and decaffeinated coffee,” says lead author Erikka Loftfield, PhD, a research fellow with the Division of Cancer Epidemiology and Genetics at the National Cancer Institute in Rockville, Maryland. Based on data on nearly half a million British people, the study, published in the July 2 edition of JAMA Internal Medicine, reported that those who enjoyed one cup of coffee a day had an 8 percent lower risk of early death, while those who drank eight or more cups a day cut their risk by 14 percent, compared with those who didn’t drink coffee. RELATED: 9 Healthy Reasons to Indulge Your Coffee Cravings
Mounting Evidence That Coffee May Be Healthful
While the study is limited by being strictly observational and not a clinical trial based on randomly selected participants, Dr. Loftfield says the research contributes to a growing number of scientific investigations showing that coffee may have beneficial health effects. “Research over the past 10 years or so has found good evidence that coffee drinking in moderation lowers the risk for heart disease, [type 2] diabetes, stroke, and Parkinson’s disease, among other conditions,” says Sarah Samaan, MD, a cardiologist at the Baylor Scott & White Legacy Heart Center in Plano, Texas, and the author of Best Practices for a Healthy Heart. “This study is particularly strong because it includes over 500,000 participants.” Samaan, who was not involved with the study, notes that one surprising finding here is that even heavy coffee drinkers appear to have a lower risk of death from heart disease and cancer, whereas some smaller studies have suggested that drinking more than three cups per day may be counterproductive to heart health. Subjects in the current observational investigation had an average age of 57 and were followed over the course of 10 years. During that time, 14,255 died. Loftfield and her colleagues based their findings on demographic, lifestyle, and genetic data. They assessed potential confounding factors, including smoking, alcohol use, tea consumption, race, education level, physical activity, and body mass index (BMI). RELATED: How Does Unfiltered Coffee Affect Your Heart?
How Does Caffeine Figure Into the Findings?
Loftfield says she was somewhat surprised to find that genetic differences affecting caffeine metabolism did not vary the results. Some people process caffeine in their bodies slower or faster depending on their genes. The authors noted that several prior studies have suggested that coffee drinkers with genes that affect caffeine metabolism may be at increased risk of cardiovascular disease. This new research, however, found that genetic variants for caffeine metabolism made no difference as far as longevity was concerned. Samaan stresses it’s not the caffeine that appears to be lowering mortality risk. “There is no evidence here that going out and buying energy drinks or caffeine pills is either safe or beneficial,” she says. Samaan also maintains concerns about the effects of drinking eight or more cups a day. “Most people would not feel well drinking that much, and I definitely would not recommend it,” she says. “Jitteriness, anxiety, insomnia and GERD (gastroesophageal reflux disease) may not kill you but could have a significant effect on quality of life.” RELATED: Is Coffee a Stimulant or a Stressor When It Comes to Heart Health?
What Is It About Coffee That Appears to Increase Longevity?
Study authors indicate that noncaffeine components may be behind the inverse associations between coffee and mortality. “There are more than a thousand chemical compounds in coffee, including various antioxidants as well as substances that may affect inflammation and energy metabolism,” says Loftfield. Antioxidants in coffee may not only reduce inflammation, according to Samaan, but also improve sensitivity to insulin and help to normalize the function of blood vessels in the heart and other organs. The study authors concluded that their findings provide further reassurance that coffee drinking can be part of a healthy diet. “For people who enjoy a good cup of coffee, and who have no side effects such as acid reflux, rapid heart rate, or anxiety with coffee, you can enjoy your morning joe with a clear conscience,” says Samaan.
