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Maternal diet vital to offspring

1 August 2003: Scientists have produced startling evidence of just how profound the effect a mother's diet is on her offspring.

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They were able to change the coat colour of baby mice simply by feeding their mothers four common nutritional supplements before and during pregnancy.

The supplements also lowered the offspring's susceptibility to obesity, diabetes and cancer.

The researchers gave some pregnant mice dietary supplements containing vitamin B12, folic acid, choline and betaine.

They gave birth to babies predominantly with brown coats.

But another group of pregnant mice given no supplements gave birth predominantly to mice with yellow coats.

Analysis showed the extra nutrients caused the coat colour change by reducing activity of a specific gene called Agouti.

The structure of the gene itself was unchanged, but the nutrients triggered a process called DNA methylation which suppressed its activity.

The researchers, from Duke University, North Carolina, believe the same process could potentially affect dozens of other genes that make humans and animals susceptible to cancer, obesity, diabetes, and even autism.

Huge implications

Lead researcher Dr Rob Waterland said: "Our study demonstrates how early environmental factors can alter gene expression without mutating the gene itself.

"The implications for humans are huge because methylation is a common event in the human genome, and it is clearly a malleable effect that is subject to subtle changes in utero."

The researchers found evidence of DNA methylation in many different types of cell throughout the bodies of the baby mice - indicating that the process was triggered at an early stage of gestation.

Professor Randy Jirtle, head of the lab which carried out the research, said: "Our data suggest these changes occur early in embryonic development, before one would even be aware of the pregnancy.

"Any environmental condition that impacts these windows in early development can result in developmental changes that are life-long, some of them beneficial and others detrimental."

Prof Jirtle said it was possible if the same changes occur in the developing sperm or eggs of the baby mice, then they could be passed down the generations, and potentially become a permanent change in the family line.

Fighting viruses

DNA methylation is caused by additional groups of atoms attaching themselves to genes.

Cells use the mechanism as a way to inactivate DNA fragments from viruses which sometimes lodge themselves in the genetic material.

But when the process goes awry the activity of the gene may be suppressed at the same time.

Dr Waterland said the fact that maternal diet seems, in some instances, to trigger the process may explain differences between individuals.

"It could, for example, explain the differences between genetically identical twins, or the disparities in the incidence of stroke between the South and the North," he said.

"The possibilities are endless."

Amanda Wynne, of the British Dietetic Association, told BBC News Online that it wasn't possible to draw direct conclusions about humans from studies on animals.

But she said: "It is well known that a well-nourished mother is likely to have a better pregnancy outcome than a malnourished mother.

"It is important to have a good healthy balanced diet during pregnancy and it may be beneficial to also have a good multi-vitamin and mineral supplement that provides levels of nutrients in line with recommended daily intakes."

The research is published in the journal Molecular and Cellular Biology.