- Vitamin–Genome Interactions
Vitamins are nutrients that are synthesized by plants and bacteria and are essential dietary components for mammals and other organisms. Vitamins function as enzyme substrates, cofactors, and prosthetic groups that enable enzyme-catalyzed reactions that otherwise could not be achieved by the apo-forms of enzymes. Vitamins also play key roles as signaling molecules. They can participate directly or indirectly in the regulation of gene expression as ligands for nuclear receptors (see Chapter 1, “Vitamin A: Nutritional Aspects of Retinoids and Carotenoids,” and Chapter 2, “Vitamin D”) or affect chromatin methylation patterns and thereby enable the genome to respond to its extracellular environment and changes in metabolism by adapting biological networks for survival or to maintain homeostasis. Vitamins are essential environmental factors for many forms of life, and therefore the evolution and survival of mammalian genomes have been inuenced by the availability and functionality of vitamins; organisms adapted to their nutritional environment through the process of selection (Figure 16.1). As a consequence of this dependence, the human genome has evolved sophisticated mechanisms to sense and regulate intracellular vitamin concentrations. Vitamins inuence key processes that are required for the evolution of the human genome, including DNA mutation, Darwinian selection, and epigenetic modications (Figure 16.1). Evolution has generated the modern human genome and its associated variation, shaping human traits including nutrient requirements and food tolerances and intolerances (Figure 16.1). This chapter highlights our understanding of vitamin-genome interactions in the evolution of the human genome and the functional consequences of human genetic variation on mammalian physiology and vitamin nutrition.