Overwhelming evidence indicates that diet is a key environmental factor affecting the incidence of many chronic diseases treated by medical practitioners on a daily basis. Information available in public gene databases, combined with advanced molecular technologies and nutrition research, provides the opportunity for the development of a new set of treatment and prevention strategies based partly on nutritional genomics. Nutrigenetics has been used for decades to prevent rare monogenic disorders such as phenylketonuria. Gene-diet interaction can now also be targeted to prevent or reduce the risk of many chronic conditions long before clinical manifestation. This multidisciplinary approach unites conventional medicine with genetics and lifestyle intervention for optimal health management.