Epigenetics during Pregnancy Can Influence Obesity

Obesity has become prevalent all across the world, yet what is to blame for the condition, genetics or the environment? Recently, a third factor has been linked to obesity: epigenetics. Studies have found that the connection between skinny mothers and obese children is partly due to epigenetics in the womb that causes the child to have an increase in appetite. The mothers must have felt a little relieved after finding this out!

Rat studies at the University of Auckland in New Zealand showed that undernourished rats during pregnancy produced overweight offspring. In a later study in 2005 they were able to show that the offspring turned out normal when the methyl tags were removed.

As for humans, two studies have been performed in the United Kingdom. The studies analyzed the diets of pregnant women, extracted the DNA from the child’s umbilical cord, then measured the body fat of the child to look for specific epigenetic marks correlated with obesity. The first test analyzed children at nine and the second test analyzed children at six. Both of the tests gave similar results, showing that epigenetics can be seen early in a child’s development. Seventy-eight genes were analyzed for epigenetic marks and only the methylation at RXRα gene was correlated with obesity. The genetic changes in RXRα had no correlation with fat levels, which indicates that epigenetics, not genetics, explains the differences in RXRα expression. The researchers also found a link between a low carbohydrate diet early in pregnancy and methylation levels of RXRα. Methylation of RXRα is thought to contribute 25% of the differences in fat levels. The statistics of the studies show that “as the percentage of the RXRα genes that were methylated went from 40% to 80%, the children’s percentage of body fat went up from 17% to 21%”. Obesity is classified as being greater than 30% BMI, so 4% can make a difference in a person’s preset conditions for obesity.

The RXRα gene is called Retinoid X Receptor-α and codes for a protein involved in the fat cell and fat metabolism pathway. Researchers think that the reason for RXRα gene methylation in mothers with a low carb diet is that somehow the mom programs the child to live in a world with scarce food resources by increasing the child’s appetite and food storage capacities. Since many of us do not live in a food-scarce world, however, these children overeat and become obese compared to children with less RXRα methylation. Fortunately, there are preventative measures in treating RXRα methylation. Mothers can add carbs to their diet to prevent methylation of the RXRα gene, and treatments for altering epigenetic tags are available. One type of treatment would be to administer micronutrients to the child. While these results have not yet been proven to be considered true, the take home message here is that pregnant women should not try to diet but should eat a healthy amount of carbs just to be safe.

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"Obesity and Overweight for Professionals: Defining | DNPAO | CDC." Centers for Disease Control and Prevention. Centers of Disease Control and Prevention, 10 June 2010. Web. 27 May 2011. .