Pregnant women have long been counseled to maintain proper nutrition. What you eat during those nine months can have lasting effects on your baby.
But what about before you are pregnant? Can what you eat — or don’t — affect your future offspring?
Animal studies show the pregnant mother’s diet can switch fetal genes off and on, which may help explain why certain genetic diseases are passed down through generations.
A new study may be the canary in the coal mine. It shows for the first time that an environmental factor during the first few days of human development can change DNA indefinitely.
Nutritional deficiencies at the time of conception can alter your baby's genes permanently, an international team of researchers at the London School of Hygiene & Tropical Medicine reported in Nature Communications.
The researchers didn’t look at how these genetic changes affect overall fetal development and the study was too short to look at the long term health of the baby. But it provides more evidence from a growing number of studies that suggest similar genetic changes may determine a child’s risk for diseases like diabetes, some mental disorders and autism.
"Can diet affect other genes? What's the biological impact of those [DNA] modifications? At the moment we don't know the answer to those questions," said Andrew Prentice, a nutritionist who contributed to the study. "But subsequent research we have — and haven't [yet] published — says it does matter."
Just as in previous animal studies, the London study showed a human mother’s diet at the earliest stage of embryonic development — conception — determines if certain genes get turned on or off.
This genetic on-and-off switch is controlled by methylation, a biochemical process where human building blocks, known as DNA, are tagged for certain biological functions.
Prentice and his team found that how much the developing embryo’s genes were tagged depended on the levels of a few micronutrients in the mom's blood at the time of conception.
“This is the first demonstration in humans that a mother's nutrition at the time of conception can change how her child's genes will be interpreted for life,” Dr. Branwen Hennig, the study’s lead scientist told BBC News.
"Our results have shown that maternal nutrition pre-conception and in early pregnancy is important and may have implications for health outcomes of the next generation,” she said. “Women should have a well-balanced diet prior to conception and during pregnancy."
The team focused their research on several B vitamins and nutrients associated with them. While the study was too limited to pinpoint exactly which ones were most important, overall they concluded that when several of these nutrients, including vitamin B12, were at lower levels in mom's blood, the genes experienced less methylation.
But here’s the thing: Prentice says the vitamin levels of women in the study were close to a normal range. Too close in fact to detect that they might actually be deficient.
"If you took the blood to your doctor, he would say they were normal," he told NPR News.
And it’s not just vitamin consumption. Mom's body mass index at the time of conception has a role to play in DNA tagging, too. The heavier the mother, the less methylation.
Keep in mind we’re not talking about women in the study packing around excess body weight. This research followed slender women in rural Gambia, where seasonal climate leads to big differences in diet between rainy and dry periods.
Scientists followed 84 pregnant women who conceived at the peak of the rainy season, and about the same number who conceived at the peak of the dry season.
Prentice said Gambian families rely on their gardens for most of their food so weather patterns "completely change the foods eaten throughout the year."
In the rainy season, the families get fewer calories but eat more nutrient-rich vegetables. In the dry season, their eatables are the equivalent of fast food — more calories but fewer vitamins.
Infants from rainy season conceptions had consistently higher rates of methylation in all genes studied which "can leave permanent marks on the child's genome on all the cells of the body," Dr. Rob Waterland of Baylor College of Medicine in Houston said of the findings.
“Our ultimate goal is to define an optimal diet for mothers-to-be that would prevent defects in the methylation process," Prentice told BBC News.
Lynette Summerill is an award-winning writer and watersports junkie who lives in San Diego with her husband and two beach loving dogs. In addition to writing about cancer-related issues for EmpowHER, her work has been seen in publications internationally.
Maternal nutrition at conception modulates DNA methylation of human metastable epialleles. Branwen J. Hennig et al. Nature Communications. Published 29 April 2014 doi:10.1038/ncomms4746
Mom’s diet before pregnancy can alter baby’s genes. Michaeleen Doucleff. NPR blog. 29 April 2014
Prepregnancy diet permanently influences DNA. Helen Briggs. BCC News. 29 April 2014
Reviewed May 1, 2014
by Michele Blacksberg RN
Edited by Jody Smith