Study: Heavy Coffee Consumption Endangers Health

ROCHESTER, Minn.The United States' coffee obsession has led to a significant surge in coffee sales, but new research shows the younger population should take caution when considering a fourth or fifth cup in a given day. Drinking more than 28 cups of coffee per week may increase mortality in people younger than 55 years, according to a new study published in Mayo Clinic Proceedings.

A multicenter research team investigated the effect of coffee consumption on death from all causes and deaths from cardiovascular disease. The team used data from more than 40,000 men and women through the Aerobics Center Longitudinal Study (ACLS) cohort, which required participants to complete medical history and lifestyle questionnaires (including information on coffee consumption).

The study showed a 21% increased mortality in those drinking more than 28 cups of coffee per week, with a greater than 50% increased mortality in both men and women younger than 55 years. No adverse effects were found in heavy coffee drinkers over age 55.

During the 17-year median follow-up period, there were 2,512 deaths (87.5% men and 12.5% women), and 32% were caused by cardiovascular disease. Those who consumed higher amounts of coffee (both men and women) were more likely to smoke and had lower levels of cardiorespiratory fitness.

Younger men had a trend toward higher mortality even at lower consumption, but this became significant at about 28 cups per week, where there was a 56% increase in mortality from all causes. Younger women who consumed more than 28 cups of coffee per week also doubled their risk of all-cause mortality compared to those who did not drink coffee.

Significantly, the results did not demonstrate any association between coffee consumption and all-cause mortality among older men and women," said senior investigator Steven Blair, PED, of the Department of Biostatistics and Epidemiology, Arnold School of Public Health, University of South Carolina. "It is also important to note that none of the doses of coffee in either men or women, whether younger or older, had any significant effects on cardiovascular mortality."

According to the latest National Coffee Drinking Study from the National Coffee Association, more than 60% of American adults drink coffee every day, consuming more than three cups per day on average. Coffee has been suspected to contribute to a variety of chronic health conditions, but results from research studies are often controversial.

Coffee is a complex mixture of chemicals containing thousands of components. Previous research shows coffee is a major source of antioxidants in the diet, and drinking coffee may provide health benefits such as a lower risk of autoimmune liver disease and prevention of breast cancer reoccurrence. However, coffee has possible adverse effects because of caffeines potential to stimulate the release of epinephrine, inhibit insulin activity and increase blood pressure and levels of homocysteine.

"Research also suggests that heavy coffee drinkers may experience additional risk through potential genetic mechanisms, or because of confounding through the deleterious effects of other risk factors with which coffee drinking is associated," said lead authors, Junxiu Liu, M.D., department of biostatistics and epidemiology, and Xuemei Sui, M.D., M.P.H., Ph.D., department of exercise science, both at the Arnold School of Public Health, University of South Carolina. Therefore, we hypothesize that the positive association between coffee and mortality may be due to the interaction of age and coffee consumption, combined with a component of genetic coffee addiction."