[Paleopsych] NS: The food you eat may change your genes for life
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Fri Nov 25 02:11:27 UTC 2005
The food you eat may change your genes for life
17 November 2005
IT SOUNDS like science fiction: simply swallowing a pill, or eating a specific
food supplement, could permanently change your behaviour for the better, or
reverse diseases such as schizophrenia, Huntington's or cancer.
Yet such treatments are looking increasingly plausible. In the latest
development, normal rats have been made to behave differently just by injecting
them with a specific amino acid. The change to their behaviour was permanent.
The amino acid altered the way the rat's genes were expressed, raising the idea
that drugs or dietary supplements might permanently halt the genetic effects
that predispose people to mental or physical illness.
It is not yet clear whether such interventions could work in humans. But there
is good reason to believe they could, as evidence mounts that a range of simple
nutrients might have such effects.
Two years ago, researchers led by Randy Jirtle of Duke University Medical
Center in Durham, North Carolina, showed that the activity of a mouse's genes
can be influenced by food supplements eaten by its mother just prior to, or
during, very early pregnancy (New Scientist, 9 August 2003, p 14). Then last
year, Moshe Szyf, Michael Meaney and colleagues at McGill University in
Montreal, Canada, showed that mothers could influence the way a rat's genes are
expressed after it has been born. If a rat is not licked, groomed and nursed
enough by its mother, chemical tags known as methyl groups are added to the DNA
of a particular gene.
The affected gene codes for the glucocorticoid receptor gene, expressed in the
hippocampus of the brain. The gene helps mediate the animal's response to
stress, and in poorly raised rats, the methylation damped down the gene's
activity. Such pups produced higher levels of stress hormones and were less
confident exploring new environments. The effect lasted for life (Nature
Neuroscience, vol 7, p 847).
Now the team has shown that a food supplement can have the same effect on
well-reared rats at 90 days old - well into adulthood. The researchers injected
L-methionine, a common amino acid and food supplement, into the brains of
well-reared rats. The amino acid methylated the glucocorticoid gene, and the
animals' behaviour changed. "They were almost exactly like the poorly raised
group," says Szyf, who announced his findings at a small meeting on
environmental epigenomics earlier this month in Durham, North Carolina.
"This opens up new ways of thinking about treating and preventing diseases
caused by how our DNA is expressed"Though the experiment impaired well-adjusted
animals, the opposite should be possible, and Szyf has already shown that a
chemical called TSA that is designed to strip away methyl groups can turn a
badly raised rat into a more normal one.
No one is envisaging injecting supplements into people's brains, but Szyf says
his study shows how important subtle nutrients and supplements can be. "Food
has a dramatic effect," he says. "But it can go both ways," he cautions.
Methionine, for instance, the supplement he used to make healthy rats stressed,
is widely available in capsule form online or in health-food stores - and the
molecules are small enough to get into the brain via the bloodstream.
Rob Waterland from Baylor College of Medicine in Houston, Texas, who attended
the meeting, says Szyf's ideas are creating a buzz, as they suggest that
methylation can influence our DNA well into adulthood. A huge number of
diseases are caused by changes to how our DNA is expressed, and this opens up
new ways of thinking about how to prevent and treat them, he says.
But Waterland points out there is still much work to be done. Substances like
methionine and TSA are, he says, a "sledgehammer approach", in that they are
likely to demethylate lots of genes, and we don't even know which they will
affect. But he speculates that techniques such as "RNA-directed DNA
methylation", so far tested only in plants but theoretically possible in
mammals, may allow us to target such methylation much more precisely.
>From issue 2526 of New Scientist magazine, 17 November 2005, page 12
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