"These specific epigenetic marks on DNA are very stable — essentially permanent, as far as we know," Waterland said.
Past research suggested environmental influences could have epigenetic effects during development in humans as well. For instance, whether Dutch women suffered through post-World War II famines during pregnancy apparently influenced how skinny or fat their children were later in life.
However, there was little strong evidence that environmental factors could trigger permanent changes to DNA throughout the human body, Waterland said.
"It's also important to note that their diet wasn't the only thing that changed — there was more physical activity due to farm labor during the rainy season, which contributed to weight loss during the rainy season and regaining of weight during the dry season," Waterland said. "Such changes contribute to what nutrients are circulating within the women."
In the new study, a nearly identical epigenetic effect was found in both blood and hair-follicle DNA of the infants. "This suggests all the cells in these kids' bodies have the same mark associated with their season of conception," Waterland said.
The long-term consequences of these epigenetic effects in children remain unknown. "We want to develop a catalog of all regions in the human genome that can get altered epigenetically by diet," Waterland said. "This will help give us the ability to tell what the likely role such changes might have in disease, and what particular diseases might be most likely to have an epigenetic component."
"Our ultimate goal is to define an optimal diet for mothers-to-be that would prevent defects in the methylation process," study author Andrew Prentice, of the London School of Hygiene & Tropical Medicine, said in a statement. "Preconceptional folic acid is already used to prevent defects in embryos. Now our research is pointing towards the need for a cocktail of nutrients, which could come from the diet or from supplements."
The scientists detailed their findings online today (April 29) in the journal Nature Communications.
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