Diet-coffee-danger under 55s-more than 28 cups a week
More Than 28 Cups of Coffee a Week May Endanger Health
in Under 55s
Aug. 15, 2013 — Nearly 400 million
cups of coffee are consumed every day in America. Drinking large amounts of
coffee may be bad for under-55s, according to a new study published in Mayo
Clinic Proceedings. A study of more than 40,000 individuals found a statistically
significant 21% increased mortality in those drinking more than 28 cups of
coffee a week and death from all causes, with a greater than 50% increased mortality risk in both men and
women younger than 55 years of age. Investigators warn that younger people in particular may
need to avoid heavy coffee consumption. No adverse effects were found in
heavy coffee drinkers aged over 55.
Drinking coffee has become a normal
daily routine for large numbers of people worldwide. According to the latest
National Coffee Drinking Study from the National Coffee Association, more than 60% of American adults
drink coffee every day, consuming on average just over three cups a day.
Coffee has long been suspected to
contribute to a variety of chronic health conditions, although earlier studies
on coffee consumption in
relation to deaths from all causes and deaths from coronary heart disease are
limited, and the results are often controversial.
A multicenter research team
investigated the effect of coffee consumption on death from all causes and
deaths from cardiovascular disease in the Aerobics Center Longitudinal Study
(ACLS) cohort, with an average follow-up period of 16 years and a relatively
large sample size of over 40,000 men and women.
Between 1979 and 1998, nearly 45,000
individuals aged between 20 and 87 years old participated and returned a
medical history questionnaire assessing lifestyle habits (including coffee
consumption) and personal and family medical history. The investigators
examined a total of 43,727 participants (33,900 men and 9,827 women) in their
final analysis.
During the 17-year median follow-up
period there were 2,512
deaths (men: 87.5%; women: 12.5%), 32% of these 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.
All participants were followed from
the baseline examination to date of death or until December 31, 2003. Deaths
from all causes and deaths from cardiovascular disease were identified through
the National Death Index or by accessing death certificates.
Younger men had a trend towards
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 had a greater than 2-fold higher
risk of all-cause mortality than those who did not drink coffee.
Senior investigator Steven H. Blair,
PED, of the Department of Biostatistics and Epidemiology, Arnold School of
Public Health, University of South Carolina, emphasizes that
"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."
Coffee is a complex mixture of
chemicals consisting of thousands of components. Recent research has found that
coffee is one of the major
sources of antioxidants in the diet and has potential beneficial effects on inflammation and
cognitive function. However, it is also well-known that coffee has
potential adverse effects because of caffeine's potential 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 investigators suggest that
younger people in particular should avoid heavy coffee consumption of more than 28 cups a week or four cups
in a typical day. However, they emphasize that further studies are
needed in different populations to assess details regarding the effects of
long-term coffee consumption and changes in coffee consumption over time on
all-cause and cardiovascular disease mortality.
Leading expert Carl J. Lavie, MD, of
the Department of Cardiovascular Diseases, Ochsner Medical Center, New Orleans,
and a co-author of this study, explains that "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."
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