Nutrigenomics is the study of effects of nutrition, nourishment or lack of nutrition on the genetic expression and anatomical or physiological changes of a living entity. Nutrigenomics aims to look at the holistic effect of diet and lifestyle on genome and on our state of health. It covers the overview of nutrigenomics and how it is associated with the prevention of diseases. The four basic tenets of nutrigenomics are, i) Improper diets are risk factors for diseases ii) Dietary chemicals alter gene expressions and change genome structure iii) The degree to which diet influences the balance between healthy and disease states may depend on an individual’s genetic makeup iv) Some diet regulated genes are likely to play a role in onset, incidence, progression, and severity of chronic diseases. Genes express themselves through proteins. But dietary protein influence gene in many ways. Enzymes are special proteins designed to influence gene expression. Some foods such as cauliflower, broccoli and Brussels and sprouts contain chemicals that instruct our gene to direct biosynthesis. In some individuals,their gene give unclear instructions for making an enzyme that metabolizes the amino acids. As a result, this amino acid causes brain damage. So, restriction of this amino acid through dietary intake will stop the damage if detected in early infancy.So, nutrigenomics plays a major role for prevention of healthproblems in humans.