[Paleopsych] NS: The food you eat may change your genes for life

[Premise Checker]

The food you eat may change your genes for life
http://www.newscientist.com/channel/health/mg18825264.800.html
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