Coffee and beer are polar opposites in the beverage world.
Coffee picks you up, and beer winds you down.
Now Prof Martin Kupiec and his team at Tel Aviv University's
Department of Molecular Microbiology and Biotechnology have discovered that the
beverages may also have opposite effects on your genome. Working with a kind of
yeast that shares many important genetic similarities with humans, the
researchers found that caffeine shortens and alcohol lengthens telomeres, the
end points of chromosomal DNA, implicated in ageing and cancer.
"For the first time we've identified a few
environmental factors that alter telomere length, and we've shown how they do
it," said Prof Kupiec. "What we learned may one day contribute to the
prevention and treatment of human diseases."
Researchers from TAU's Blavatnik School of Computer Science
and Columbia University's Department of Biological Sciences collaborated on the
research, published in PLOS Genetics.
Telomeres, made of DNA and proteins, mark the ends of the
strands of DNA in our chromosomes. They are essential to ensuring that the DNA
strands are repaired and copied correctly. Every time a cell duplicates, the
chromosomes are copied into the new cell with slightly shorter telomeres.
Eventually, the telomeres become too short, and the cell dies. Only foetal and
cancer cells have mechanisms to avoid this fate; they go on reproducing
The researchers set out to expand on a 2004 study by Nobel
Prize-winning molecular biologist Prof Elizabeth Blackburn, which suggested
that emotional stress causes the shortening of the telomeres characteristic of
ageing, presumably by generating free radicals in the cells. The researchers
grew yeast cells in conditions that generate free radicals to test the effect
on telomere length. They were surprised to find that the length did not change.
They went on to expose the yeast cells to 12 other
environmental stressors. Most of the stressors from temperature and pH changes to
various drugs and chemicals had no effect on telomere length. But a low
concentration of caffeine, similar to the amount found in a shot of espresso,
shortened telomeres, and exposure to a 5-to-7% ethanol solution lengthened
From yeasts to you
To understand these changes, the TAU researchers scanned 6 000
strains of the yeast, each with a different gene deactivated. They then
conducted genetic tests on the strains with the longest and shortest telomeres,
revealing that two genes, Rap1 and Rif1, are the main players mediating
environmental stressors and telomere length.
In total, some 400
genes interact to maintain telomere length, the TAU researchers note,
underscoring the importance of this gene network in maintaining the stability
of the genome. Strikingly, most of these yeast genes are also present in the
"This is the first time anyone has analysed a complex
system in which all of the genes affecting it are known," said Prof
Kupiec. "It turns out that telomere length is something that's very exact,
which suggests that precision is critical and should be protected from
More laboratory work is needed to prove a causal
relationship, not a mere correlation, between telomere length and ageing or
cancer, the researchers say. Only then will they know whether human telomeres
respond to the same signals as yeast, potentially leading to medical treatments
and dietary guidelines. For now, Prof Kupiec suggests, "Try to relax and
drink a little coffee and a little beer."