Caffeine
Consumption Associated with
Less Severe Liver Fibrosis
 Researchers
from the National Institute of Diabetes and
Digestive and Kidney Diseases (NIDDK) determined
that patients with chronic hepatitis C virus
(HCV) who consumed more than 308 mg of caffeine
daily had milder liver fibrosis. The daily
amount of caffeine intake found to be beneficial
is equivalent to 2.25 cups of regular coffee.
Other sources of caffeine beyond coffee did
not have the same therapeutic effect.
Liver fibrosis or scaring of the liver is
the second stage of liver disease and is characterized
by a degradation of liver function due to
accumulated connective tissue. Past studies
have looked at modifiable behaviors, such
as coffee consumption, that mitigate the progression
of liver disease.
A
number of studies have looked at the benefits
of higher coffee intake with results that include:
lower prevalence of chronic liver disease, reduced
risk of hepatocellular carcinoma (liver cancer),
and lower risk of death from cirrhosis complications.
"From data collected to date it remains
unclear whether coffee itself, or caffeine provides
the beneficial effect," said Apurva Modi,
MD, lead author of the current study that focuses
on caffeine intake and its impact on liver fibrosis.
From January 2006 to November 2008 all patients
evaluated in the Liver Disease Branch of the
National Institutes of Health were asked to
complete a questionnaire to determine caffeine
consumption. Questions were asked pertaining
to all sources of caffeine including regular
and diet soft drinks; regular and decaffeinated
coffee; black, green, Chinese and herbal teas;
cocoa and hot chocolate; caffeine-fortified
drinks; chocolate candy; caffeine pills; and
medications with caffeine. Participants were
asked about their frequency of caffeine consumption,
which was quantified as never; 1-3 times per
month; 1, 2-4, or 5-6 times per week; 1, 2-3,
4-5, and 6 or more times per day.
The analysis included 177 participants who were
undergoing liver biopsy with a mean age of 51
years and mean body mass index (BMI) of 27.5.
Of those in the cohort 56% were male, 59% Caucasian,
19% Black, 19% Asian, 3% Hispanic, and 68% had
chronic HCV.
Daily
consumption of caffeine from food and beverages
raged from none to 1028 mg/day with an average
of 195 mg/day, which is equivalent to 1.4 cups
of coffee daily. Most caffeine consumed came
from regular coffee (71%) followed by caffeinated
soda (13%), and black tea (4%). Repeated administration
of the questionnaire within a 6-month period
displayed consistent responses suggesting caffeine
intake does not significantly change over time.
Patients with an Ishak fibrosis score of less
than 3 had a mean caffeine intake of 212 mg/day
compared with 154 mg/day for those with more
advanced fibrosis. The Ishak fibrosis score
is the preferred system that measures degree
of liver scarring with 0 representing no fibrosis
through 6 indicating cirrhosis. For each 67
mg increase in caffeine consumption (about one
half cup of coffee) there was a 14% decrease
in the odds of advanced fibrosis for patients
with HCV.
"Our
data suggest that a beneficial effect requires
caffeine consumption above a threshold of approximately
2 coffee-cup equivalents daily," noted
Dr. Modi. The protective effects of consuming
more than 308 mg of caffeine daily persisted
after controlling for age, sex, race, liver
disease, BMI, and alcohol intake for all study
participants.
Researchers further evaluated caffeine and coffee
separately to determine the individual effect
of each on fibrosis. Results showed that consumption
of caffeinated soda, green or black tea was
not associated with reduced liver fibrosis.
However, a significant protective effect could
have been missed due to small numbers, as 71%
of total caffeine consumed came from coffee.
Caffeinated
coffee had the most pronounced effect on reduced
liver fibrosis. The authors suggest that further
research is needed to determine if the protective
benefits of coffee/caffeine intake plateau at
amounts beyond the daily consumption threshold.
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