Exploring the implications of nutrigenetics on dietetic practice: An Illustrative Case Study
Creators: name: Kelly, Nathaniel
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2011

description: A connection between food and health has been known to exist since the dawn of history. However, the advent of modern science refined this concept to an understanding that our health depends upon obtaining certain nutrients in specific quantities. This heralded the concept that improper nutrition may directly lead to disease states and spawned dozens of professions and fields of research that focus on the relationship between nutrition and health. This in turn has led to an exponential growth in our understanding of human nutrition and to the creation of dietary recommendations such as the Institute of Medicine’s Dietary Reference Intakes (DRI’s). Recently, advances in genetic technologies such as the sequencing of the human genome have begun to revolutionize the field of nutrition and radically altering the direction of research. Hundreds of genetic variants that predispose individuals to common diseases have been identified and as research continues the number of known disease-predisposing polymorphisms will multiply. However, human health does not solely depend on our genes but also on our environment. Understanding how these two factors interact is paramount to disease prevention and our diet has been identified as one of the most important factors to interact with our genes. Hence thecreation of a new field within nutrition, nutrigenetics. Nutrigenetics aims to understand how the genetic makeup of an individual coordinates their response to diet. Therefore, nutrigenetics considers the genetic polymorphisms of an individual and how these variations interact with disease risk and diet. As research progresses, nutrigenetics will produce information that will assist clinicians in identifying the optimal diet for a given individual, i.e., personalized nutrition. If these goals are to be realized the field of nutrition must move beyond epidemiological studies using genetically uncharacterized populations and incorporate more complex models that account for cellular and molecular biology coupled with biochemistry and genetics. The burgeoning field of nutrigenetics has already discovered dozens of “candidate gene variants” which may confer a heightened sensitivity to specific nutritional factors and are known to modulate disease risk. Some of these genes have functionally important variations that are highly prevalent in the population. Genetic variation within these genes may explain discrepancies in previous epidemiologic studies that sought to find interactions between disease risk and diet. These polymorphisms also have the potential to alter individual optimal nutrition based upon genotype and in time their characterization may become indispensable to the field of clinical nutrition and dietetics. Given the enormous potential of nutrigenetics to redefine optimal nutrition and to create truly personalized nutrition, the field of dietetics must find a way to incorporate these advances into nutrition therapy. Commercial nutrigenetic testing is rapidly rising in popularity and decreasing in price. However, these tests used by consumers on their own lack the credibility that validated genetic tools in the hands of licensed nutrition professionals such as registered dietitians (RDs) can provide. RDs may view commercial nutrigenetic tests as tools or as competitors depending upon point of view. However, if the use of genetic information is to be of practical value in clinical practice, dietitians must be familiar with genetic terminology and stay reasonably informed of current nutrigenetic research. Furthermore, dietitians who seek to utilize genetic testing in clinical practice must have a firm grasp upon the moral, ethical, and legal implications of inherent to genetic testing. This paper will examine the current research surrounding five “candidate gene variants” and discuss how particular polymorphisms in these genes may affect clinical nutrition therapy. To provide a context for this discussion the following case scenario was constructed: A woman comes to a private dietetic practice seeking help interpreting the results of a genetic test she took after seeing an advertisement online. She is particularly concerned about her risk of breast cancer. Her mother recently died of the disease and the results mention breast cancer risk. She would also like help losing a “few extra pounds” she has gained over the past several years. She is a healthy 35 year old female who is 177cm tall, weighs 82kg (BMI= 26.2), and who exercises moderately. Her genetic test results have revealed the following genetic polymorphisms: APOA2 -265 CC, DHFR -ND, MGMT -427 AG, CAT -262 CT APOA2 -265 CC, DHFR -ND, MGMT -427 AG, XRCC1 -26304 CT, CAT -262 CT.