By Michèle Turcotte, MS, RD/LDN

Traditionally, nutritional research has concentrated on nutrient deficiencies and impaired health. Recently, though, a new field of study has emerged. Termed nutritional genomics—or nutrigenomics—this scientific research analyzes the relationship between human genomes and lifestyle choices. In other words, it asks the question: “How do dietary and lifestyle choices influence the functioning of living beings from their cells, to their whole bodies, to entire populations?”

Nutrigenomics may help people at-risk for chronic diseases

To understand this idea a little better, let’s first define the word “genome.” A genome is the sum total of all the genetic information in an organism; its instruction book; the blueprint that directs the development and functioning of living organisms. Thanks to scientific understanding of genomes, within a decade it’s likely that doctors will be able take patients’ genetic profiles and use them to identify specific diseases they are at-risk for developing.

After 20 years of human gene sequencing and state-of-the-art technologies, a new set of treatment and prevention paradigms are emerging. At the junction between health, diet, and genomes, nutrigenomics may lead to personalized diet prescriptions for restoring health and fitness, as well as for preventing diet-related disease. The information could create a demand for nutrition information among patients at-risk for developing chronic diseases.

5 Fundamentals of nutrigenomics

Essentially the study of the relationship between diet and food (how, together, they interact with specific genes to increase the risk of certain diseases), nutrigenomics has five fundamental ideas behind it:

1. Under certain circumstances—in some individuals—diet may seriously increase the risk factors for diseases.
2. Common dietary chemicals can act on the human genome and alter gene expression/structure.
3. The amount that diet influences the balance between a healthy and diseased state may depend on a person’s genetic makeup.
4. Some diet-modulated genes are likely to play a role in the onset, incidence, progression, and/or severity of chronic diseases.
5. Chronic disease can be prevented or cured with dietary intervention based on a personalized nutrition plan.

Nutrigenomics and the future

Here’s an example of the way nutrigenomics might work to help people with cardiovascular disease (CVD). Like many chronic diseases (e.g. diabetes, obesity, and cancer), CVD is caused by both genetic and environmental factors. Until now, most prevention and treatment plans have focused on modifying a patient’s lifestyle and environment. However, now that scientists understand that inflammation also has a role in heart disease—and that some individuals with normal cholesterol may still have an increased risk of CVD (due to pro-inflammatory gene variations)—nutrigenomics can make specific diet recommendations to reduce inflammation. Dietary recommendations like omega-3 fatty acid-rich foods (walnuts, salmon and avocado), vitamin E, and green tea may help to reduce inflammation. Further research is needed to evaluate the combined effect of anti-inflammatory dietary components on individuals with a genetic predisposition to inflammation.

Nutrigenomics could lead to food combinations that best suit a client’s genetic profile. One example involves the carcinogens that are in the crust that forms on barbequed or broiled meat. The crust itself is not harmful except in the first part of a two-step breakdown process. Some people have genetic variants that cause a build-up of carcinogens in step one of this breakdown process which may predispose them to developing cancer. The fact that certain nutrients in garlic slow down step one and other compounds (sulforaphane in broccoli) boost step two is important to communicate. Thus, the patient should be advised to eat more garlic and broccoli dishes. Scientific evidence like this helps a registered dietitian to make such specific diet recommendations.

Nutrigenomics Is Proven To Work

Nutrition is already being used to prevent genetic diseases and has shown remarkable success. One disease showing promise is Phenylketonuria, a genetic disorder that causes mental retardation and which is 100% the result of genetic factors. Thanks to newborn screening and early intervention, dietary treatment has prevented the disease. Unfortunately, most diseases won’t be this clear-cut. In most cases, diseases are caused by a combination of genetic predisposition and environmental factors. Genetic factors are things like taste preferences (which are genetically determined). As gene/diet interactions are better defined, it’s possible that more genetically-based diseases may be prevented through dietary intervention. How exciting to know that there is another tool for health care and dietetics professionals to use in helping people live healthier lives. Many in this community are very excited about the possibilities genomic research will bring to the future of dietetics and food science!