In exciting new research from the Friedman School's Jiantao Ma and Alice H. Lichtenstein, diet quality may affect our health by changing DNA methylation levels. This hypothesis has been tested using animal models but has not been well-studied in humans. The study found that diet quality was associated with methylation levels at 30 DNA sites, most of which were also associated with health outcomes. This finding provides strong evidence to support their hypothesis that diet quality affects our health through regulating DNA methylation levels.
In the study, they characterized diet quality using two commonly used diet quality scores and measured over 400,000 whole blood-derived DNA methylation markers (CpGs) in 9,724 individuals. They identified 30 CpGs associated with diet quality scores in individuals of European ancestry. Among these CpGs, the research found that 12 CpGs were associated with mortality. For example, this study found greater diet quality scores (i.e., healthier diet) were associated with increased DNA methylation levels at cg18181703 located at gene named SOCS3.
The research also found increased DNA methylation levels at cg18181703 was associated with lower mortality. In addition, they conducted Mendelian randomization (MR) analysis (a type of statistical analysis utilizing genetic information to test causal relations). The MR analysis revealed that 6 CpGs (of the 30 CpGs) were likely causal factors for cardiovascular risk factors (e.g., body mass index, triglycerides, and type 2 diabetes).