Pregnant moms' diet may affect obesity risk of offspring

The offspring of mothers who eat a high fat diet are more likely to have a higher risk of obesity later in life, a study released Friday shows. The study by researchers at Baylor College of Medicine, in Houston, says that it does not matter if the mother is obese or of normal weight, and what matters is if the mother eats a low fat diet during pregnancy. In the study, scientists find that SIRT1, a member of the sirtuin family, responds to excess levels of fat calories in the pregnant mom's diet by chemically modifying key locations on the histone protein. The levels and activity of SIRT1 are diminished in the offspring of mothers who ate the high fat diet, the study shows. Histones are proteins that aid in packaging DNA into chromosomes and making it possible for the DNA to be transcribed into the RNA that begins the process of making a protein. The addition or deletion of molecules to the histones so-called epigenetic changes that occur after the genetic code is written - affect how genes are expressed. "Because SIRT1 levels were unchanged in the mothers on the low fat diet, and only decreased with high fat diet, we are confident that a high fat diet, but not maternal obesity, is responsible for this change," said Melissa Suter, the first author of the study. Researchers found the infants whose mothers ate the high fat diet during pregnancy had less SIRT1 than those in the other groups. Infants whose mothers ate a healthy diet during pregnancy - whether the moms were obese or not - had normal levels of SIRT1 and its activity. "As a practicing obstetrician, I can confidently advise my patients that we have evidence today that taking steps to change your diet in pregnancy to one of moderate fat intake will be of at least early benefit to your infant - whether you are obese, overweight, or fortunate enough to be a healthy weight," said Kjersti Aagaard, associate professor of obstetrics and gynecology at Baylor College of Medicine.