Department of Food Science and Human Nutrition
Extension
Colorado State University
Fort Collins, CO 80523-1571
Healthy Heart Beats
July-September 2007
Vol 29, Issue 3
Did You Know?....
Q: I have recently heard that companies are offering genetic testing to determine the correct diet that I should be eating. Can you tell me more and if I should have these tests done?
A: We all have experience with a relative or friend that maintains low cholesterol levels despite eating meals laden with high-fat junk foods and other people whose cholesterol levels become elevated by merely looking at a bowl of ice cream. How are we to explain such dramatic variation between people? One answer is genetics. While we tend to look at the human genome as a single entity we must remember that it is diversity within the human genome that makes each of us unique. So unique in fact, that each of us has a personal chemical and metabolic profile as unique as our outward appearance. It is this diversity in genetic code between individuals which is forming the basis for the emerging discipline called nutrigenomics.
Nutrigenomics is a sub-field of nutrition which studies the interaction between nutrients and an individual's genetic code. By studying how an individual's genotype interacts with the nutrients in their diet, professionals in the field of nutrigenomics ultimately seek to be able to provide each of us with an unique dietary prescription that is based on our own set of genes. The basis for much of the work currently being performed in the field of nutrigenomics is the identification of single base-pair changes in a person's genetic code which are called single nucleotide polymorphisms (SNP's). Most of the time these changes in the genetic blueprint have no discernable health effects but in some cases these SNP's alter the way we can process or use nutrients leading to increased risk of chronic disease. The most extensively studied SNP, which occurs in 10-15% of the population, is that of an enzyme which participates in the pathway we use to metabolize vitamin folate. Studies have shown that people with this SNP may require more folate in their diets. Companies which use genetic testing to provide gene-specific personalized diets base their prescriptions on 15-20 currently discovered SNP's which are in some fashion related to nutrient metabolism. Unfortunately, current knowledge within the filed of nutrigenomics is unable to provide us with the detailed information as to the exact nutrient requirements required to counteract each specific SNP. This makes a dietary prescription nothing more than a shot in the dark for these companies. Furthermore, Americans already eating a well balanced diet full of fruits and vegetables consume micronutrients at a level which may overcome any currently discovered nutrient related SNP's.
In conclusion, the field of nutrigenomics is a new and exciting branch of nutrition that promises to answer many questions that have baffled researcher regarding the diversity individual responses on nutrient intake and chronic disease and in the future may offer us a pathway to optimum health by providing unique dietary prescriptions based on our individual genotype. However, current knowledge on gene-based dietary prescription is limited to the point that by following current dietary guidelines stressing a high intake of fresh fruits and vegetables we can reap similar health benefits without the $300-$500 price tag required for current gene-based dietary prescriptions.
Source: Dr. Mike Bizeau, Food Science and Human Nutrition, Colorado State University
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