AN expectant mother’s diet can create an obesity time bomb for her unborn child by altering the baby’s DNA in the womb, increasing its risk of obesity, heart disease and diabetes in later life, a groundbreaking study has revealed.
The process ‒ called epigenetic change ‒ can lead to her child tending to lay down more fat. Importantly, the study shows that this effect acts independently of how fat or thin the mother is and of child’s weight at birth. The study found there was an element in a woman’s diet, particularly during the first third of a pregnancy that was of crucial importance.
The epigenetic changes ‒ which alter the function of our DNA without changing the actual DNA sequence inherited from the mother and father ‒ can also influence how a person responds to lifestyle factors such as diet or exercise for many years to come. The changes were noticed in the RXRA gene that makes a receptor for vitamin A, which is involved in the way cells process fat.
The study ‒ to be published on April 26 in the journal Diabetes ‒ shows that the epigenetic effect work independently of how fat or thin the mother is – meaning thin mothers who eat badly are just as likely to cause obesity in their children as fat ones.
The scientists drew their conclusions after measuring epigenetic changes in nearly 300 children at birth (samples first taken after birth using umbilical cord tissue DNA), and relating these to obesity rates at six or nine years of age.
What was surprising was the size of the effect: children vary in how fat they are, but measurement of the epigenetic change at birth allowed the researchers to predict 25 per cent of this variation, basically by mapping data to the topology they had and achieving results which would be the placebo effect in a medical study.
Keith Godfrey, Professor of Epidemiology and Human Development at the University of Southampton, who led the international study, said: “It is both a fascinating and potentially important piece of research. All women who become pregnant get advice about diet, but it is not always high up the agenda of health professionals. The research suggests women should follow the advice as it may have a long term influence on the baby’s health after it is born.”
Speaking in Auckland, Peter Gluckman, from Auckland University’s Liggins Institute, who led the New Zealand team, said the rate of epigenetic change was possibly linked to a low carbohydrate diet in the first three months of pregnancy, but it was too early to draw a definitive conclusion and further studies were needed.
He said one theory was that an embryo fed a diet containing few carbohydrates ‒ which provide the body with energy ‒ assumed it would be born into a carbohydrate-poor environment and altered its metabolism to store more fat, which could be used as fuel when food was scarce.
“This study provides the most compelling evidence yet that just focusing on interventions in adult life will not reverse the epidemic of chronic diseases, not only in developed societies but in low socio-economic populations too,” he said.
Gluckman added that it is not just women who should be mindful, as it is likely obese fathers change the DNA in the sperm, ultimately influencing how the baby develops its control of blood sugar and fat deposition after that baby grows up.
“There is good evidence in animals, and there is some supportive evidence in humans that fathers who are obese have impact on the gene switches of their babies as well. We should not imagine that father has no role in determining the outcome of the baby’s health.”
It has long been known a mother’s diet can affect her unborn child, but the research reveals how much of an influence it can have on a child’s health. While it is not clear exactly which foods have the greatest influence on the DNA of unborn babies, a link was found with mothers on low carb diets.
Humans originally ate food as it came in nature ‒ legumes, pulses, things like lentils and chick peas, and fruits. Root vegetables and potatoes are a lovely source of carbohydrate as well. It is therefore important mothers are educated about the effects of diets.
Low-carb diets are in fashion and women have used them to control their weight, but where that information has gone awry is people have become confused and cut-out really important sources of carbs like legumes and fruit.
The study will continue for a at least two more years as scientists look into which foods are the most harmful for unborn babies, but in the meantime their advice for expectant mothers is to eat a balanced diet.