A new study highlights a risk of liver disease resulting from exposure to excess fat and calories during fetal development. Childhood obesity has been correlated with the dramatic rise in incidence of type 2 diabetes and nonalcoholic fatty liver disease among youth in the United States. Previous studies have shown that high-fat diets, obesity, and diabetes during pregnancy are associated with metabolic problems in the offspring. However, the mechanisms for these findings remain relatively unknown, and it can be difficult to distinguish between the effects of obesity and the effects of a diet that could lead to obesity. Current dietary guidelines for mothers with gestational diabetes include substituting fats for carbohydrates in the diet to help lower blood glucose levels. However, the results from this study suggest the importance of considering potential adverse effects of excess dietary fat when adjusting a diet.
Scientists recently explored the effects of a high-fat diet during pregnancy on liver disease in offspring, using an animal model in which some mothers were more susceptible to obesity and diabetes than others. These studies, done in non-human primates, suggest that a chronic high-fat diet results in a significantly increased risk of fetal fatty liver disease that persists after birth. This finding held true whether or not the mothers were themselves obese or had diabetes. Pregnant animals fed a high-fat, high-calorie diet produced offspring that had a three-fold increase in triglyceride fat in the liver. Furthermore, the offspring displayed evidence of increased liver stress during gestation, consistent with the development of fatty liver disease. Elevated levels of triglycerides persisted in the offspring following birth. Additionally, as the offspring grew, those from mothers fed a high-fat diet had a two-fold increase in percent body fat compared to offspring of mothers who ate a standard diet. Importantly, after female animals were consistently fed a high-fat diet for four years, switching them to a lower calorie, low-fat diet reduced fetal liver abnormalities in their subsequent offspring, even though some of the mothers remained obese and insulin resistant. These studies suggest that a maternal high-fat diet may result in increased fat transfer to the fetus, and that unhealthy levels of fats in maternal blood (rather than diabetes or obesity) could potentially be the predominant cause of some future metabolic disorders in offspring. However, it is also possible that the health effects observed in offspring were the result of the high total calories fed to their mothers, rather than the percentage of calories from fat.
Fatty liver disease is an increasingly important cause of liver failure. Recognition of the role of the prenatal environment in the genesis of fatty liver provides a potential intervention to prevent the disorder. By shedding new light on dietary contributors to adverse health conditions, this study can direct future research efforts toward developing strategies to preempt disease.