Obese parents who eat a high-kilojoule diet around the time of conception could be responsible for making their child more susceptible to diabetes and obesity during the course of their life, an international study has shown.
New research from Germany, published online this week in Nature Genetics, has found that obese mice can pass on their overeating tendencies to their offspring through both the sperm and egg.
Scientists planted embryos from obese parents into healthy-weight surrogate mothers and found that offspring with two obese parents gained more weight than expected.
They reasoned that although the offspring’s hard-wired genes hadn't changed, the parents' obesity and overeating activities during conception and gestation had re-programmed their child’s gene-reading 'software' to make them more susceptible to obesity and diabetes.
This process is known as epigenetics: a series of reversible alterations that modify your genetic material but do not change your DNA.
“We show that a parental high-fat diet renders offspring more susceptible to developing obesity and diabetes…” the study reads.
Past human evidence has also shown that the food mum eats during pregnancy and in the postnatal period influences the future health of her baby.
“The epigenetic inheritance of acquired metabolic disorders may contribute to the current obesity and diabetes pandemic.”
“This study shows that by feeding obese mice a high fat diet, you can essentially change the sperm and the eggs,” says Prof Collins.
“Past human evidence has also shown that the food mum eats during pregnancy and in the postnatal period influences the future health of her baby.
“But what this study adds is the information saying that what the father eats is also important. We know much less about how what a father eats influences a child’s weight.”
Prof Collins explains that although a person’s genes determine if you will have green or blue eyes, epigenetics can affect the way the gene controls a certain characteristic.
“It can be altered based on the environment: the food that you eat, what’s in the mother’s blood, her nutrients based on diet or lifestyle.
“So in some way, it’s like genes are the TV channel and epigenetics are the TV’s volume control.
“While we may have thought that obesity was just due to a mother’s genes, this mice study says dad’s lifestyle also matters because the volume of the genes comes from dad. We are not sure about whether this is true in humans yet but it is true in mice.”
During the research, the scientists fed genetically identical mice a high-fat, low-fat or normal diet for six weeks.
The mice which were fed a high-fat diet developed obesity and glucose intolerance, as expected.
The authors then produced embryos using combinations of sperm and eggs from the parent mice, which had been fed different diets and implanted the embryos into healthy surrogate mothers.
This allowed the authors to separate environmental factors from epigenetic factors present only within the sperm or eggs. The adult offspring were then fed a high-fat diet.
Offspring with two obese parents gained significantly more weight on a high-fat diet than those with only one obese parent.
Offspring with two obese parents gained significantly more weight on a high-fat diet than those with only one obese parent. Offspring of two lean parents gained the least weight on a high-fat diet. The authors observed similar patterns for glucose intolerance.
They conclude that epigenetic factors in gametes have an important role in the transmission of obesity and diabetes risk from parents to offspring.
Prof Collins believes the study demonstrates the need to help and support adults to live a healthy lifestyle: for themselves and their children.
“So if you are planning a pregnancy, this is a call to get on board with a healthy lifestyle before you have a child, so there is a clear pathway to bring up a child with a healthy lifestyle.”
Studies on humans are yet to be conducted to determine whether the high-fat diets of obese parents would yield the same effect on children.