Is obesity caused by what you eat or what you inherit? In a March 2016 study published in Taylor & Francis Group, “Nutrition has a pervasive impact on cardiac microRNA expression in isogenic mice”, it seems that the former holds true.
Prenatal vs. Postnatal Exposure to Obesity
As of 2015, almost 40% of the American adult population is obese. This growing disorder seems to have an effect on children as well, with 20.5% of teenagers and 17.7% of children aged 6-11 considered obese as of 2012 (Centers for Disease Control and Prevention). The source of a person’s obesity can stem from the genes acquired from an obese parent or from the choices made in his or her diet. As mentioned in this recent study, offspring of obese parents may have obesity prenatally programmed in their DNA, leaving them susceptible to develop the disease. Nonetheless, the postnatal consumption of the popular Western diet has more harmful repercussions.
What is microRNA, and What Does it Have to do with Obesity?
MicroRNA (or miRNA) are small, noncoding RNA molecules, many of which are capable of altering gene expression. For example, miRNA in the heart have the ability to hormonally control metabolism and are dysregulated by metabolic disorders such as obesity. Based on this knowledge, scientists sought to discover the different ways prenatal and postnatal causes of obesity can alter the expression of cardiac miRNA.
Nutrition’s Impact on miRNA Expression
In this particular study, scientists separated mice into two groups: a high-fat Western diet experimental group, and a low-fat diet control group. They sequenced RNA from the cardiac tissue of mice from both lean and obese parents. They discovered changes in the expression of 8 types of cardiac miRNA in mice that were exposed to maternal obesity and a high-fat Western diet. In response to exposure to a postnatal Western diet alone, offspring of lean parents showed changes in expressions of 33 types of cardiac miRNA, and offspring of obese parents showed changes in expressions of 46 types of cardiac miRNA.
Evidently, changes were much more common in postnatal exposure to nutrition than in prenatal exposure to obesity, despite the higher number of miRNA changes in offspring from obese parents. The results of this study show that prenatal exposure to obesity can indeed have a genetic impact, but the dominant contributing factor is a postnatal diet.
From Mice to Humans
While this experiment was done on mice, the majority of changes in cardiac miRNA were caused by the Western diet that is commonly consumed by humans. Cardiac miRNA expression plays a significant role in the body’s control on metabolism, and diet has a strong effect on miRNA alteration. The results of this study correlate with the statistics mentioned earlier; percentages of Americans with obesity grow higher with age, implying that it is developed throughout life rather than being present at birth. When questioning whether metabolic disorders such as obesity are the fault of genes or food, think twice about the nutrition of the common diet.