Genetics' new frontier: What mom eats, weighs in pregnancy can set child up for obesity, diabetes

Cracking the human genome is already old news for those riding the next wave of genetic research. The rising field of epigenetics is revealing how diet, behavior and the environment are reprogramming the genes we're dealt at conception.

Although your DNA was locked in the moment your parents' egg and sperm met, how those genes get expressed depends on what happened next. "Most chronic diseases that occur in adulthood have their origins in the first 1,000 days after conception," said Kent Thornburg, an epigenetics researcher at Oregon Health and Science University.

What's more, the epigenetic changes that happen in the womb get passed on to future generations.

Sorry, moms. That means once again, the pressure is on you.

"If your mom was obese while she was pregnant with you, you're marked," said Philip Wood, professor at Sanford Burnham Research Institute in Lake Nona. You will have an uphill battle fighting off excess weight and its ill effects, including diabetes and heart disease, even if you're adopted and raised by slim parents, he said.

The findings are significant as medical science works to identify causes and cures for the two most serious and costly epidemics facing America: obesity and diabetes.

We don't understand all of the mechanisms, but they likely involve maternal circulating hormones, such as leptin and insulin, and glucose levels that can alter how the placenta develops and what nutrients cross it, said Tracy Bale, associate professor of neuroscience at the University of Pennsylvania School of Veterinary Medicine, who has done epigenetic studies on animals.

Studies have shown that these effects can be handed down to the next generation, she added.

Rewriting the script

Epigenetics can silence or draw out the expression of genes.

"If DNA is the hardware, epigenetics is the software that tells genes what to do," said Randy Jirtle, an epigenetics researcher at Duke University Medical Center.

A study conducted on mice, and published in 2003 in Molecular Cell Biology, illustrated the effects of diet on genes. The mice in the study carried the agouti gene, which humans also have.

When scientists fed pregnant mice a certain diet that silenced the gene, the baby mice came out yellow, fat and prone to diabetes and cancer. When they fed the mice diets that activated the gene — a diet rich in folic acid, B vitamins and choline — mice came out skinny, brown and not susceptible to disease.

"The mice were genetically identical," said Jirtle, who was part of the study. "The only difference was what the mothers ate."

Granted these are mice, not humans, he added, "but the experiment showed that a mother's diet can shape the epigenome of her offspring."...