Americans are big coffee drinkers, consuming more than 400 million cups each day. But new research has found that drinking four cups of coffee a day could lead to numerous health problems and an increased mortality risk, according to a study published in the journal Mayo Clinic Proceedings.
Researchers from the US conducted an analysis on the link between coffee consumption and causes of death, using data from the Aerobic Center Longitudinal Study (ACLS), The National Death Index, and by assessing death certificates.
Around 45,000 men and women between 20 and 87 years of age participated in the study between 1979 and 1998.
All participants were asked to complete a medical questionnaire disclosing lifestyle habits, including their coffee consumption, as well as personal and family medical history.
The study subjects were monitored over an average 17-year period from the first evaluation up until their death, or until December 31, 2003.
During this time, there were 2,512 deaths, with 32% of these caused by cardiovascular disease.
Researchers say four cups of coffee a day may lead to a 50% higher mortality risk for those under the age of 55.
The research showed that those who drank more that 28 cups of coffee a week had a 21% higher risk of mortality as a result of death from all causes, compared with participants who drank fewer than 28 cups a week.
For those under the age of 55 who drank more than 28 cups of coffee a week there was a 50% higher mortality risk.
Additionally, the researchers found that those who consumed higher amounts of coffee were more likely to smoke, and showed lower levels of cardiovascular fitness.
In men specifically, younger men showed signs of increased mortality even at lower consumption than 28 cups of coffee a week, showing a 56% increase from all causes.
Younger women who consumed more than 28 cups of coffee a week also revealed double the risk of mortality compared with women who drank less.
Steven Blair of the department of biostatistics and epidemiology at the Arnold School of Public Health at the University of South Carolina, says of the results:
"Significantly, the results did not demonstrate any association between coffee consumption and all-cause mortality among older men and women.
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."
The researchers warn that young people should avoid coffee consumption of more than four cups a day, but they add that further studies are required within different populations in order to analyze the effects of long-term coffee consumption linked to all-cause and cardiovascular disease mortality.
However, many studies have praised the consumption of coffee, saying it may have many health benefits. Recent research from the Harvard School of Public Health revealed that consuming between two and four cups of coffee a day may reduce the risk of suicide in adults by 50%.
Carl Lavie of the department of cardiovascular disease at the Ochsner Medical Center in New Orleans, and co-author of this most recent study, says:
"There continues to be considerable debate about the health effects of caffeine, and coffee specifically, with some reports suggesting toxicity and some even suggesting beneficial effects."