Nutritional Genomics—Preparing for the Future!
Prior to the completion of the Human Genome Project in April 2003, the healthcare practitioner’s efforts to include genotypic information in any health assessment relied on family history, except for rare single gene mutation conditions like phenylketonuria, or PKU.
For example, for a client with a family history of several siblings, parents or grandparents diagnosed with celiac disease, one could identify increased risk of celiac and proceed with assessment by ruling out gastrointestinal tract issues, ruling out dermatitis herpatiforme during a nutrition physical exam and requesting a celiac panel blood test from their physician.
In 1956, Roger J. Williams, the discoverer of pantothenic acid, catapulted the concept of biochemical individuality regarding nutrients and metabolism into the nutrition science community. His insight provided early hints of today’s nutritional genomics science.
“Genetics is central to nutrition therapy, because genetic factors influence metabolism for all individuals.”
-What Dietitians Need to Know about Genetics : http://www.nchpeg.org/nutrition/index.php?option=com_content&view=article&id=398
With the fast-paced emergence of the science of nutritional genomics, new evidence is becoming strong enough to be used in some clinical applications. It is especially valuable for healthcare practitioners practicing integrative and functional medicine with an emphasis on biochemical individuality. It must be recognized that in order to develop the skills to incorporate genomic data into a nutrition assessment and to understand the clinical implications of a patient’s genomic testing results (their genotype), one must obtain post-graduate nutritional genomics training and refresh their understanding of nutritional biochemistry. This is a new science for all of healthcare. Educational programs for health professionals are beginning to add nutritional genomics to their curricula, but currently healthcare practitioners need to self-initiate additional study and/or mentorship in the topic to enable them to practice with the necessary level of expertise.
The application of nutritional genomics in clinical practice is currently structured around some important principles so as to help ensure ethical and evidence-based practice. The following principles have been suggested by a few U.S. practitioners that have practice-based experience in clinical nutritional genomics, such as Dr. Ben Lynch, Dr. Amy Yasko, Colleen Draper, MS, RDN, Deanna Minich, PhD, CNS, Jeff Bland, PhD, CNS and others. These nutritional genomics practitioners acknowledge that the client is the most effective teacher of each individual’s genotype and phenotype during the hearing of the patient’s story.
1) Use of tests: Nutritional Genomic test results are not diagnostic.
Genomic testing is new to healthcare. It is performed by a growing number of labs and is available direct-to-consumer. These factors present a challenge to healthcare professionals as they interact with clients who already have their tests, possibly without correct interpretation and clinical relevance, as well as assess the validity of testing methods.
It is important for practitioners to keep the genomic testing in perspective.1-3 These tests are not diagnostic for the nutritionist scope of practice.4 Genomic testing results are valuable additions to nutrition data as antecedents that are collected during the initial assessment to enhance the entire patient’s story; they help illuminate the client’s biochemical capabilities.
“The knowledge gained from nutritional genomics requires an evidence-based approach to validate that personalized recommendations result in health benefits to individuals and do not cause harm. Whether or not the knowledge gained from nutritional genomics can be integrated into the everyday lives of consumers is yet unknown.”
Academy of Nutrition and Dietetics 2014 Position Paper: Nutrigenomics2
2) Biochemistry: Nutritional biochemistry and knowledge of biochemical pathways is required to clinically apply genomics.
Simply described, genes direct associated enzymes. Thanks to today’s pharmaceutical industry, we have descriptions of a large number of biochemical pathways, especially biotransformation, as the body detoxifies waste molecules. The nutritional biochemistry content taught in a typical nutrition and dietetics program requires supplementation in the area of the gene-enzyme-nutrient co-factor association to be able to comprehend the genomics world.
3) Start simple: Start with learning one family of genes.
The genomics science is accelerating; so month-by-month, the dietitian interested in nutritional genomics must have a system of keeping abreast of the new evidence. To begin training in nutritional genomics, learn one biochemical and gene pathway until comfortable identifying gene-enzyme-nutrient-diet intake relationships. By learning one pathway at a time, one’s dietitian toolbox will soon include nutritional genomics.
Some gene groups to consider when beginning to study nutritional genomics: methylation, including Vitamin D Receptor (VDR); detoxification genes (which interact with some methylation genes), like Glutathione-S-Transferase genes; Cytochrome P450 genes; and Catechol-O-methyltransferase (COMT).
4) Find a mentor: Study and seek mentors experienced in clinical nutritional genomics to aid learning skills of assessment and interventions, including genomic testing.
Although the hands-on experience of working with clients builds practical skills, nothing tops working with a mentor who can impart experience and expertise in this advanced field of dietetics. For example, working with a mentor to study client cases can accelerate the learning curve in incorporating single nucleotide polymorphism (SNP) information with biochemical, medical and patient history information.
Some excellent mentoring is currently available through the following links:
- Genetics and Nutrition: A Resource for Dietetic Faculty and Practitioners. http://www.nchpeg.org
- Institute for Functional Medicine www.functionalmedicine.org (free six-part series on genomics: Functional Medicine. and Genomics) http://www.functionalmedicine.org/listing.aspx?cid=124
- Dr. Amy Yasko, MD. www.dramyyasko.com
- Dr. Ben Lynch, ND. www.MTHFR.net; www.seekinghealth.org
- Genome: Your Health is Personal. Quarterly magazine that covers the personalized medicine stories of today and the breakthroughs of tomorrow, so that patients have information they need to get the care they deserve. Genomemag.com
5) Environmental influences on gene expression.
The science of epigenetics studies gene expression changes from environmental exposures without changing the DNA of a gene.6,7 It follows closely on the heels of nutritional genomics. This may be the most important aspect of how nutrient intake and environmental exposures direct gene expression. Randy Jirtle’s experiment on agouti mice demonstrated the profound influence nutrients play on genes.8,9
“Epigenetics exists at the intersection between genetics and the environment. The goal is to use epigenetics to anticipate health in the individual and, more importantly, the population.”
Majnik AV, Lane RH. Epigenomics. February 2014
6) KEY MESSAGE: “Don’t treat the test result, treat the whole client.”
Throughout integrative medicine, the common quote above emphasizes the importance of connecting every test result with clinically relevant factors. This is especially true in the use of genomic testing for a nutrition assessment. A good example of this is the MTHFR 677C and MTHFR 1298C. A homozygous positive SNP implies reduced efficiency of the conversion of folate precursors to the bioactive form of 5-MTHF. A responsible assessment would consider the genotype for MTHFR and then test functional markers related to the function of the MTHFR 677C/1298C genes. Some of these biomarkers would be: MCV/MCH (cofactors for RBC volume); homocysteine (5-MTHF dependent in the homocysteine metabolic pathway); the urine organic acid form Formiminoglutamic acid (FIGLU)—a specific cellular functional marker for adequate 5-MTHF; and signs and symptoms related to poor methylation (medical symptoms questionnaire (MSQ)). If the clinical biomarkers indicate inadequate or insufficient 5-MTHF, then there is reasonable indication the client may benefit from increased folate foods in addition to supplementation with the bioactive 5-MTHF. Following the nutrition care process steps, this intervention step would be monitored and evaluated for effective outcomes. Because methylation is ubiquitous to human metabolism, it can have broad beneficial effects in many conditions.
Hopefully, considering genomic data in assessments related to health / disease associations and the ability of diet to positively modulate metabolism will become the basis of more robust research portfolios that will strengthen the future evidence for clinical applications.
Keep your eye on the future!
- Ozdemir V, Kolker E. Precision Nutrition 4.0: a big data and ethics foresight analysis-convergence of agrigenomics, nutrigenomics, nutriproteomics and nutrimetabolomics. OMICS. 2016;20(2):69-75.
- Position and Practice Paper Update for 2014: Nutrigenomics. JAND. 2014;114:299-312.
- Pavlidis C, Lanara Z, Balasopoulou A, Nebel JC, Katsila T, Patrinos GP. Meta-Analysis of Genes in Commercially Available Nutrigenomic Tests Denotes Lack of Association with Dietary Intake and Nutrient-Related Pathologies. OMICS. 2015;19(9):512-520.
- Pavlidis C, Nebel JC, Katsila T, Patrinos GP. Nutrigenomics 2.0: The need for ongoing and independent evaluation and synthesis of commercial nutrigenomics tests’ scientific knowledge base for responsible innovation. OMICS. 2016;20:65-68.
- Yasko methylation pathway. Dr. Amy Asko Web site. www.dramyyasko.com. Accessed March 14, 2016.
- Burris HH, Baccarelli AA, Wright RO, Wright RJ. Epigenetics: linking social and environmental exposures to preterm birth. Pediatr Res. 2016;79:136-40.
- Epigenetics: linking social and environmental exposures to preterm birth. Ped Res. 2016;79:136-140.
- Jirtle, R. Epigenome: the program for human health and disease. Epigenomics. 2009;1(1):13-16.
- Waterland RA, Travisano M, Tahiliani AG. Diet-induced hypermethylation at agouti viable yellow is not inherited transgenerationally through the female. FASEB J. 2007;21(12):3380-3385.
- Salamon M. The Ultimate Selfie: what healthy people can learn from getting their genome sequenced. Genomemag.com. http://genomemag.com/ultimate-selfie/#.V17Hx641pPo [accessed June 13, 2016]
©2016 Nutritional Genomics—Current State of Clinical Application: EE: Noland
Diana Noland, MPH, RD, CCN
Diana Noland owns a busy functional nutrition therapy practice. She has been a speaker for the American Dietetic Association FNCE Conference and served as faculty and chair of the Nutrition Advisory Board of the Institute of Functional Medicine (IFM).