Epigenomics or epigenetics refers to the modification of DNA that can influence the phenotype through changing gene expression without altering the nucleotide sequence of the DNA. Two examples are methylation of DNA and acetylation of the histone DNA-binding proteins. Dietary components - both nutrients and nonnutrients - can influence these epigenetic events, altering genetic expression and potentially modifying disease risk. Some of these epigenetic changes appear to be heritable. Understanding the role that diet and nutrition play in modifying genetic expression is complex given the range of food choices, the diversity of nutrient intakes, the individual differences in genetic backgrounds and intestinal physiological environments where food is metabolized, as well as the impact on and acceptance of new technologies by consumers.