During my time as an undergraduate, I had many different interests that I was not sure I could integrate into one career. However, genetic counseling continued to appeal to me because of the opportunity to create new roles in a variety of healthcare areas. Although most are familiar with the few core specialties (prenatal, cancer, and pediatrics), I was surprised to learn about opportunities in disciplines like cardiology, neurology, industry, and ophthalmology. Something that particularly caught my attention was the development of nutritional genomics.
Nutritional genomics has two main branches: nutrigenetics and nutrigenomics. Nutrigenetics is a field that explores how our bodies respond to what we consume. Understanding these genetic impacts may help practitioners recommend specific workouts and supplements to clients. On the other hand, nutrigenomics describes how what we consume impacts gene expression. During my undergraduate career, I participated in nutrigenomic research that investigated how dietary bioactives can impact gene expression that play important roles in various metabolism pathways. I was fascinated by how the food we consume has the potential to change our genetic ecosystem.
In a NSGC Genetic Counselors and You Podcast episode titled “My Nutrition, My Genes,” registered dietician nutritionist Jill West described her experiences using genetic testing to adjust diet and maximize prevention strategies. For example, she shared that genetic testing can be used to understand how patients metabolize caffeine and sodium. If someone’s genetic testing reveals they are a slow metabolizer of these compounds, they may want to limit their consumption, as it poses a larger risk for heart disease for this individual as compared to someone who doesn’t have a genetically based sensitivity.
More recently, the DNA Today podcast hosted an episode with Dr. Yael Joffe, the founder of the company 3X4 Genetics. Her company allows healthcare providers to access genetic testing to inform diet and exercise plans for their patients. Dr. Joffe is passionate about educating practitioners about genetics so they could integrate testing and polygenic risk scores to work with individuals to change their daily lives. In this episode, she clarifies how her company differs from traditional medical genetics by studying “common gene changes … [that] do not cause disease. [These changes] interact with the choices we make in our life: the food we eat, the exercise we do, and therefore give us some control on how our genes express themselves for our lives.” She emphasized how, to get the most value from genes, there needs to be a population of healthcare providers trained in interpreting genetics.
More than 26 million individuals have done direct-to-consumer genetic testing (DTC-GT). According to research by Roosan et al. (2023), there are currently eighteen commercial laboratories in the United States and Europe offering DTC-GT. These companies promise information about personalized recommendations from diets, exercise performance, and fertility optimization. Some DTC-GT can be physician-mediated, meaning practitioners order testing kits from these companies for patients in their practice. While some DTC-GT base their results on monogenic gene changes, others base their results on RNA studies or polygenic risk scores. However, it can sometimes be difficult to know exactly where companies are extracting evidence from to provide health information.
There are many studies that show associations between specific genetic changes and different metabolism effects in individuals. Yet, the main question continues to be whether genetic testing can truly be a catalyst for individuals’ behavior change in relation to health. The hope is that if individuals learn more about their own bodies and get more personalized recommendations, then they will be willing to comply in the long-term with health-promoting behaviors. Even though there is an increased consumer interest in pursuing genetic testing for personalized recommendations, there is still no consensus on the evidence of nutritional genomic testing.
The Academy of Nutrition and Dietetics performed a two-part systematic review in 2021 (Robinson et al.). They looked at 10 articles describing randomized, controlled trials that looked at the impacts of using genetic testing for nutrition counseling. These trials analyzed a variety of nutritional measures from macronutrient distribution to fruit and vegetable intake. The only significant changes were seen with high-risk variant carriers, who were more likely than low-risk gene variant carriers to reduce their intake of sodium and alcohol in response to genetic results (Hendershot et al., Nielsen et al.). In all other studies, there were no significant differences in dietary intake of those that received nutrition-based genetic counseling compared to a control group. Therefore, the Academy concluded that there is insufficient evidence to suggest significant effects of nutrition-based genetic testing and it is not yet ready to be routinely incorporated into dietetics practices. Previous studies also found no changes in behavioral modifications in response to DTC-GT results of condition susceptibility (Bloss et al., Gray et al.).
It’s important to keep in mind that there are many lifestyle changes that people can make to improve health with genetic testing. Genetic advice may help motivate some but may only be more significant than common advice for sub-populations of people who respond to environmental factors uniquely. However, we can also appreciate that this field is very young and gene-lifestyle interactions for polygenic traits need to be further investigated so we can determine if nutrition-based genetic testing can be translated into clinical recommendations and public health initiatives.
From a quick Google search, you can find PhD programs in Nutrigenomics from institutions like University of the Balearic Islands and University of Cape Town. Besides these specialized programs, many dietetic programs do not have coursework in genetics. While individuals, like Dr. Yael Joffe, have tried to respond to these gaps in genetic education, I am interested if there is also a space for genetic counselors. Roosan et al. (2023), conducted a systematic literature review on nutrigenomics counseling and identified that interested practitioners report lacking genetic counseling skills and opportunities to integrate them in clinical practice. Genetic counselors may be best trained to interpret nutritional genetic testing results and help clients adopt personalized plans. Genetic counselors already have roles with psychiatric genetic counseling, which similarly conveys information about multifactorial conditions and potential management strategies.
It’s exciting to me to think that genetic
counselors can continue to have new roles within and beyond the healthcare
system. While the effectiveness of clinically used nutritional-based genetic
testing still seems uncertain, we cannot deny that this field has a future.
Genetic tests have already been used by healthcare providers to inform health
interventions. The question remains to what extent this service will be
beneficial to public health and clinical practice. Do you feel nutrigenomics
has a basis for growth? Do genetic counselors have a responsibility to support
and be involved in the development of this field?
Dineen, K. (Host). (2022, May). #185 Nutrigenomics with Yael Joffe. [Audio podcast]. Retrieved from https://www.youtube.com/watch?v=7SABJeGUwVQ
Guasch-Ferré, M., Dashti, H. S., & Merino, J. (2018). Nutritional Genomics and Direct-to-Consumer Genetic Testing: An Overview. Advances in nutrition (Bethesda, Md.), 9(2), 128–135. https://doi.org/10.1093/advances/nmy001
Hendershot, C. S., Otto, J. M., Collins, S. E., Liang, T., & Wall, T. L. (2010). Evaluation of a brief web-based genetic feedback intervention for reducing alcohol-related health risks associated with ALDH2. Annals of behavioral medicine : a publication of the Society of Behavioral Medicine, 40(1), 77–88. https://doi.org/10.1007/s12160-010-9207-3
Nielsen, D. E., & El-Sohemy, A. (2014). Disclosure of genetic information and change in dietary intake: a randomized controlled trial. PloS one, 9(11), e112665. https://doi.org/10.1371/journal.pone.0112665
Regalado A. More than 26 million people have taken an at-home ancestry test. MIT Technology Review. https://www. technologyreview.com/s/612880/morethan-26-million-people-have-taken-an-athome-ancestry-test/. Published February 11, 2019. Accessed July 10, 2023.
Robinson, K., Rozga, M., Braakhuis, A., Ellis, A., Monnard, C. R., Sinley, R., Wanner, A., & Vargas, A. J. (2021). Effect of Incorporating Genetic Testing Results into Nutrition Counseling and Care on Dietary Intake: An Evidence Analysis Center Systematic Review-Part I. Journal of the Academy of Nutrition and Dietetics, 121(3), 553–581.e3. https://doi.org/10.1016/j.jand.2020.04.001
Roosan, D., Wu, Y., Tran, M., Huang, Y., Baskys, A., & Roosan, M. R. (2023). Opportunities to integrate nutrigenomics into clinical practice and patient counseling. European journal of clinical nutrition, 77(1), 36–44. https://doi.org/10.1038/s41430-022-01146-x
Wong, K. (Host). My Nutrition, My Genes. [Audio podcast]. Retrieved from https://open.spotify.com/episode/2dx96ucyQtT0e9evVyENmD?si=50b9eb41866746f2
