August 16, 2013
Four Cups Of Coffee Per Day Could Be Bad For The Younger Generation
April Flowers for redOrbit.com - Your Universe Online
Every day in the US, approximately 400 million cups of coffee are consumed. For people under 55 years of age, drinking large amounts of coffee could be bad for your health. The study, published in Mayo Clinic Proceedings, examined more than 40,000 individuals to find a statistically significant 21 percent increase in mortality risk for those drinking more than 28 cups of coffee a week and death from all causes, with a greater than 50 percent increased mortality risk in both men and women younger than 55 years of age. The researchers note younger people in particular need to avoid heavy coffee consumption as no adverse effects were found in heavy coffee drinkers over the age of 55.
Scientists have long suspected coffee contributes to a variety of chronic health conditions. Previous studies on coffee consumption in relation to deaths from all causes and deaths from coronary heart disease, however, have been limited and the results are often controversial.
The current study employed a multicenter research team to investigate the effect of coffee consumption on death from all causes and deaths from cardiovascular disease in the Aerobics Center Longitudinal Study (ACLS) cohort. The cohort had a relatively large sample size, over 40,000 men and women, with an average follow-up period of 16 years.
Almost 45,000 participants between 20 and 87 years of age returned a medical history questionnaire between 1979 and 1998. The questionnaire assessed lifestyle habits (including coffee consumption) and personal and family medical history. In the final analysis, the investigators examined a total of 43,727 participants (33,900 men and 9,827 women).
During the follow-up period, 2,512 participants died – 87.5 percent were men, 12.5 percent women. Cardiovascular disease caused 32 percent of the overall deaths. The analysis found those who consumed higher amounts of coffee, regardless of gender, were more likely to smoke and had lower levels of cardiorespiratory fitness.
The entire cohort was followed from the baseline date of examination until the date of death, or December 31, 2003. The researchers identified deaths from all causes using the National Death Index or by accessing death certificates.
The team found younger men had a trend towards higher mortality even at lower coffee consumption levels. This trend became significant at about 28 cups per week with a 56 percent increase in death from all causes. Younger women consuming more than 28 cups of coffee a week had a greater than 2-fold higher risk of all-cause mortality than those who did not drink coffee.
Steven H. Blair, PED, of the Department of Biostatistics and Epidemiology, Arnold School of Public Health, University of South Carolina, states, "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."
A complex mixture of chemicals consisting of thousands of components, coffee has been found to be one of the major sources of antioxidants in the diet and has potential beneficial effects on inflammation and cognitive function. It is also well-known, however, coffee has potential adverse effects because of the potential of caffeine to stimulate the release of epinephrine, inhibit insulin activity, and increase blood pressure and levels of homocysteine.
"Thus, all of these mechanisms could counterbalance one another. 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," say lead authors, Junxiu Liu, MD, Department of Biostatistics and Epidemiology, and Xuemei Sui, MD, MPH, PhD, 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."
The research team suggests younger people in particular should avoid heavy coffee consumption of more than 28 cups a week, or four cups a day. They note, however, further research is necessary in different populations to assess the effects of long-term coffee consumption and changes in coffee consumption over time on all-cause and cardiovascular disease mortality in greater detail.
Carl J. Lavie, MD, of the Department of Cardiovascular Diseases, Ochsner Medical Center, New Orleans, explains, "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."