Coffee drinkers rejoice: your liver and skin thank you
By John Timmer
| Published: August 01, 2007 – 05:20PM CT
We tend to view habits that are referred to as addictions as
necessarily bad things. In recent years, however, there has been good
news for those who consider themselves hooked on things like red wine,
green tea and chocolate: these complex substances appear to contain
some chemicals that actually enhance human health. Two recent
publications suggest that we may be able to add coffee to that list.
The first comes from the June issue of Hepatology,
a journal devoted to the study of the liver. Some researchers
(primarily from espresso-mad Italy) performed a meta-analysis of
studies that tracked liver cancer, the third most common cause of
cancer deaths globally, and pulled out data related to coffee
consumption. Overall, this happy addiction appeared to correlate with a
41 percent reduction in the risk for cancer.
The benefit held up well across a variety of studies, including both
case-controlled and cohort designs. It also persisted across geographic
regions, with the frequent drinkers of Southern Europe and the rare
sippers in Japan seeing a protective effect. There was also a dose
effect, with heavy drinkers seeing even more protection, and
consumption even benefitted those with signs of liver damage, which is
often a precursor to cancers of the organ. It was one of the more
convincing data sets I’ve seen in this sort of analysis.
At PNAS, a study
skipped the coffee, and headed straight for putting caffeine in the
drinking water of some mice. Nevertheless, they suggested that the mice
dosed themselves in a manner typical of us humans: “The plasma
concentration of caffeine in mice ingesting caffeine (0.1–0.4
mg/ml drinking water) is similar to that in the plasma of most coffee
drinkers (one to four cups per day).” This caffeine was coupled with
the mouse equivalent of a voluntary exercise program, which involved
placing a running wheel in the cage.
The researchers looked at how the combination of exercise and
caffeine affected a potential path to cancer, the response of cells to
ultraviolet light exposure (something that often accompanies exercise).
Cells exposed to UV have two choices: suffer the damage, or commit an
organized form of cell suicide called apoptosis. It’s thought that the
apoptotic response prevents cancer by killing off anything that may
have picked up DNA damage, and hence a propensity to cancerous growth.
Either the exercise or caffeine alone caused a slight uptick in the
number of cells undergoing apoptosis following UV exposure. Combining
the two, however, caused a far more dramatic increase, over 400 percent
compared to the sedentary, uncaffeinated controls. This was more than
simply adding the two separate effects, suggesting that caffeine and
exercise acted synergistically. As an added benefit, the subdermal fat
layer in the mice shrank dramatically in these animals. These results
suggest that making caffeine part of your exercise program may give it
an extra boost, and help limit the damage caused by any of the exercise
you pursue outdoors.
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