The HNRCA Series: How Nutrigenomics will tell you which diet is best for you

The HNRCA is where I will be spending the next five to six years of my life, along with 12 other Friedman students. This series of articles will explore the cutting-edge research that’s currently taking place at the Center.

by Hassan Dashti

The term “nutrigenomics” merges two separate but important terms we are all very familiar with at Friedman: nutrition and genetics. Yet, defining the term can be confusing. Nutrigenomics is a new field of study that examines the relationship between nutrition and genetics. It is a two-way street: food you ingest affects gene expression in your body, and the genes expressed in your body affects the food you ingest.

What facilitated the emergence of this new science is recent breakthroughs in the field of genetics and nutrition alike. Dr. Jose Ordovas is a senior scientist and the director of the Nutrition and Genomics Laboratory at the HNRCA, and has worked in the field since the 1980s. Discussing this emerging phenomenon, Dr. Ordovas noted that “when you merge two areas that are very complex, then the development of the combined science has to be slow.”

In order to conduct research in nutrigenomics, you have to be able to determine and analyze the genes of an individual. That was difficult to do until the completion of the Human Genome Project in 2001. And in its early years, it was extremely expensive and time-consuming. Dr. Ordovas explained, “When I started back in the early ‘80s, you had to spend an entire week, if you were lucky, to process 20 samples to look at one polymorphism [a region in the DNA that is highly variable in a population]. Now, with the development of gene-chips, one million polymorphisms can be processed in a matter of hours.” Along the same lines, although nutrition science got started in the 1920s, only in the late 20th century has the field really become widespread. As scientists gained interest in this field, there emerged newer findings as well. Scientists now supplement their cell biology research with nutrigenomics research in order to better disclose possible causation of certain diseases or relationships between traits.

Numerous recent findings in the field of nutrigenomics have improved our understanding of complex diseases. Recent investigations have identified correlations between genetic polymorphisms, which are variations at one site of a gene, and important widespread diseases including diabetes and cancer. For example, a genetic variation on one gene has been identified to be closely associated with lactose intolerance. Individuals with a different form of this gene caused by a single nucleotide change become lactose intolerant and therefore cannot metabolize lactose in their diet. Likewise, individuals with an inability to metabolize folate, which could lead to artery stiffness, have been identified to have a different form of the gene MTHFR which is critical for proper folate metabolism.

Although some of these polymorphisms might seem rare, the field is growing at an unprecedented rate, resulting in the identification of thousands of critical disease-related polymorphisms. And with this information, nutrition scientists can suggest a diet that is best suited for a person based on his or her genotype. Dr. Ordovas explained, “when people go to the gas station, they know which is the right gas to use for their car. Nutrigenomics works similarly by selecting the right diet based on a person’s genes.” By doing so, we can reduce the risk of diseases and unwanted rates in a population.

At the HNRCA, Dr. Ordovas is investigating numerous lipid-related traits including obesity. The lab is primarily focused on identifying polymorphisms and genes that are better suited for diets with varying dietary fats. That is, they are identifying genes involved in lipid metabolism. By identifying those genes, they can identify individuals who are predisposed to obesity by identifying the variant of the gene they have.

In addition, Dr. Ordovas is using a newer, more extensive approach for identifying disease-associated genes. Genome-wide association studies, or GWAS, compare the entire genetic content of thousands of individuals with and without a trait in order to identify which genes are more likely associated with a trait of interest. It is a hypothesis-free approach that does not restrict the investigation of a researcher to any region of the DNA. Dr. Ordovas was able to identify some obesity- and lipid-associated genes using this approach by comparing genes of normal and obese individuals. In addition, Dr. Ordovas is considering how circadian rhythms could be associated with different diet-related diseases.

Although the current primary focus of nutrigenomics is only identifying genes and polymorphisms associated with dietary traits, all of this information will eventually be put into use. It will be used to revert the effect of unwanted traits and diseases. By identifying which genes are involved in a trait, and by understanding the pathways a gene is involved in, we can modulate the expression of the gene to eliminate unwanted effects. This can and will be done through changes in the diet where food will have the ability to attenuate unwanted traits. It’s true that the field is only at its primary stage, but its future is certainly very promising.

Hassan Dashti is a student in the Biochemical and Molecular Nutrition program. He is an international student from Kuwait, and completed his undergraduate studies at the University of Pennsylvania. Even since he started learning about nutrition science at Penn, he has been excited by the research taking place in this field.

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