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Nutritional Genomics

Nutritional Genomics

Welcome to the Nutritional Genomics Systematic Review
 

Registered Dietitian Nutritionists (RDNs) deliver personalized nutrition counseling and care by tailoring dietary guidance to an individual’s health status, physical environment, diet history and beliefs and values, among other factors. Many methods of determining individual nutrition needs are well established and accepted, such as through assessment of body mass index, body composition or HbA1c. Other methods of nutrition assessment, and the interventions that follow, are relatively new to dietetics practice, such as assessment of genetics, microbiome or metabolome, and it is unclear if or how these nutrition assessment technologies should be utilized in practice. 

Nutritional genomics is an umbrella term that refers to the inter-relationships between genetics, diet, and disease or dysfunction. Considerable evidence suggests significant associations between genetic variants and phenotype and/or response to a specific dietary interventions. However, it is unclear how this knowledge can be applied in dietetics practice to improve dietary intake or intermediate or health outcomes. In addition, it is unclear if utilizing genetic results to inform nutrition practice offers added benefits beyond those of “traditional” personalized nutrition provided by RDNs. Thus, the Academy of Nutrition and Dietetics’ Evidence Analysis Center sought to determine if there was enough high-quality evidence examining incorporation of genetic testing results into nutrition counseling and care to inform practitioners about utilizing this technology in practice. 

Scoping Review
This project began in 2018 with a thorough evidence scoping review designed to examine the extent, range and nature of the available research of the topic. The results of the scoping review were used to guide the focus of the systematic review, including the development of the research question.

Systematic Review
The aim of this systematic review project was to examine: In children and adults, what is the effect of incorporating results of genetic testing into nutrition counseling and care, compared to an alternative intervention or control group, on nutrition-related outcomes?

Systematic Review Key Findings

  • In the past decade, several randomized controlled trials have investigated the effect of incorporating results of genetic testing into nutrition counseling or care. However, these studies are heterogeneous, particularly in terms of how the intervention was delivered (ex: one contact online vs. 6 months of care from an RDN) and the genes/genotypes/SNPs targeted. 
  • Researchers reported very few health outcomes such as disease incidence or prevention of disease progression. When health outcomes were reported, evidence quality was low. 
  • Generally, there were no differences in anthropometric measures, lipid profiles or glucose homeostasis measures according to if genetic test results were incorporated into nutrition counseling and care compared to standard care and evidence quality was graded as Limited-Fair. 
  • For the total study populations, incorporating results of genetic testing into nutrition counseling and care generally did not result in significant changes in dietary intake compared to counseling and care that did not incorporate genetic testing results. There was some evidence that these findings may vary according to the genotype/SNP of the participant and, hence, if the participant received specific dietary guidance in regards to the genotype/SNP under investigation. Evidence quality was graded as Limited-Fair.

Use the left navigation to view the Nutritional Genomics systematic review. Expand the section below titled Project Team and Disclosures for a listing of individuals who contributed to the development of the project, disclosures and project funding information.

Manuscripts
Several articles based on this review have been published. Expand the section below titled Resources and Articles for the article abstracts and citations.

updated 9/17/2020

  • Systematic Review Project Team and Disclosures (2019)

    The following individuals contributed their valuable time and expertise to this project:
     

    Workgroup Members

    • Ashley J. Vargas, PhD, MPH, RDN, FAND, Chair
      Scientist, National Institutes of Health, North Bethesda, MD, USA
    • Andrea J. Braakhuis, PhD, RD
      Senior Lecturer, The University of Auckland, Auckland, New Zealand
    • Amy C. Ellis, PhD, MPH, RDN, LD
      Associate Professor, The University of Alabama, Tuscaloosa, AL, USA
    • Cathriona R. Monnard, PhD, RDN
      Postdoctoral Researcher, University of Fribourg, Fribourg, Switzerland
    • Katie N. Robinson, PhD, MPH, RD, LD
      Medical Science Liaison, Scientific and Medical Affairs, Abbott Nutrition, Columbus, OH, USA

    Project Leaders

    • Mary R. Rozga, PhD, RDN, Project Manager
      Nutrition Researcher, Academy of Nutrition and Dietetics, Chicago, IL
    • Rachel C. Sinley, PhD, RD, Lead Analyst
      Assistant Professor, Metropolitan State University of Denver, Denver, CO, USA
    • Amanda Wanner, MLIS, AHIP, Medical Librarian
      Consultant, Kelowna, British Columbia, Canada
    • Deepa Handu, PhD, RDN, Methodologist
      Senior Scientist, Academy of Nutrition and Dietetics, Chicago, IL, USA

    Evidence Analysts

    • Lyanne Chin, PhD candidate, RDN
      University of Wisconsin, Madison, WI, USA
    • Alanna Clark, MPH
      Public Health Nutritionist (WIC), Mecklenburg County, Carolinas Healthcare Systems, Charlotte, NC, USA
    • Courtney T. Luecking, MPH, MS, RDN
      Doctoral Candidate, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
    • Telma Moreira, MS, RDN, LD, CNSC
      Clinical Dietitian, MD Anderson Cancer Center, Houston, TX, USA
    • Laurie Inacio, MS, RD
      Consultant, Brunswick, ME, USA
    • Melanie M. Mott, PhD, RD
      Clinical Writer, Dynamed Plus, Ipswich, MA, USA
    • Alexandra MacMillan Uribe, MS, RD (resigned 5/31/19)
      Graduate Research Assistant, University of Wisconsin, Madison, WI, USA

    Financial Contributors

    • Academy of Nutrition and Dietetics
    • Academy of Nutrition and Dietetics Foundation
    • Dietitians in Integrative and Functional Medicine Dietetic Practice Group

    The views or interests of the funding bodies did not influence the development of this systematic review.

    Disclosures of Potential Conflicts of Interest: In the interest of full disclosure, the Academy has adopted the policy of revealing relationships workgroup members have with companies that sell products or services that are relevant to this topic. Workgroup members are required to disclose potential conflicts of interest by completing the Academy Conflict of Interest Form. It should not be assumed that these financial interests will have an adverse impact on the content, but they are noted here to fully inform readers.

    • Ellis A: Received grant funding from American Heart Association; registered as an authorized provider of Nutrigenomix® services (no compensation).

     

  • Resources and Articles (2020)

    The following resources are available:

    • Consenus Report of the Academy of Nutrition and Dietetics: Incorporating Genetic Testing into Nutrition Care. Personalization of nutrition advice is a process already familiar to registered dietitian nutritionists, but it is not yet clear whether incorporating genetic results as an added layer of precision improves nutrition-related outcomes. Therefore, an independent workgroup of experts, supported by the Academy’s Evidence Analysis Center staff, conducted a systematic review to examine the level of evidence measuring the effect of incorporating genetic testing results into nutrition counseling and care, compared to an alternative intervention or control group, on nutrition-related outcomes. This systematic review revealed that only weak quality evidence is available in the scientific literature and observed that this field is still maturing. Therefore, at present, there is insufficient scientific evidence to determine whether there are effects of incorporating genetic testing into nutrition practice. The workgroup prepared this Consensus Report based on this systematic review to provide considerations for the practical application of incorporating genetic testing into the nutrition care process. Braakhuis A, Monnard CR, Ellis A, Rozga M. J Acad Nutr Diet. 2020; S2212-2672(20)30337-3. doi: 10.1016/j.jand.2020.04.002.
    • Effect of Incorporating Genetic Testing Results into Nutrition Counseling and Care on Dietary Intake: An Evidence Analysis Center Systematic Review - Part I. Consumer interest in personalized nutrition based on nutrigenetic testing is growing. Recently, multiple, randomized controlled trials have sought to understand whether incorporating genetic information into dietary counseling alters dietary outcomes. The objective of this systematic review was to examine how incorporating genetic information into nutrition counseling and care, compared to an alternative intervention or control group, impacts dietary outcomes. This is the first of a 2-part systematic review series. Part II reports anthropometric, biochemical, and disease-specific outcomes. Peer-reviewed randomized controlled trials were identified through a systematic literature search of multiple databases, screened for eligibility, and critically reviewed and synthesized. Conclusion statements were graded to determine quality of evidence for each dietary outcome reported. Reported outcomes include intake of total energy and macronutrients, micronutrients, foods, food groups, food components (added sugar, caffeine, and alcohol), and composite diet scores. Ten articles representing 8 unique randomized controlled trials met inclusion criteria. Of 15 conclusion statements (evidence grades: Weak to Moderate), 13 concluded there was no significant effect of incorporating genetic information into nutrition counseling/care on dietary outcomes. Limited data suggested that carriers of higher-risk gene variants were more likely than carriers of low-risk gene variants to significantly reduce intake of sodium and alcohol in response to nutrition counseling that incorporated genetic results. Included studies differed in quality, selected genetic variants, timing and intensity of intervention, sample size, dietary assessment tools, and population characteristics. Therefore, strong conclusions could not be drawn. Collaboration between the Academy of Nutrition and Dietetics and professional nutrigenetic societies would likely prove valuable in prioritizing which genetic variants and targeted nutrition messages have the most potential to alter dietary outcomes in a given patient subpopulation and, thus, should be the targets of future research. Robinson K, Rozga M, Braakhuis A, Ellis A, Monnard CR, Sinley R, Wanner A, Vargas AJ. J Acad Nutr Diet. 2020; S2212-2672(20)30336-1. doi: 10.1016/j.jand.2020.04.001   
    • Effect of Incorporating Genetic Testing Results into Nutrition Counseling and Care on Health Outcomes: An Evidence Analysis Center Systematic Review - Part II. In recent years, literature examining implementation of nutritional genomics into clinical practice has increased, including publication of several randomized controlled trials (RCTs). This systematic review addressed the following question: In children and adults, what is the effect of incorporating results of genetic testing into nutrition counseling and care compared with an alternative intervention or control group, on nutrition-related health outcomes? A literature search of MEDLINE, Embase, PsycINFO, CINAHL, and other databases was conducted for peer-reviewed RCTs published from January 2008 until December 2018. An international workgroup consisting of registered dietitian nutritionists, systematic review methodologists, and evidence analysts screened and reviewed articles, summarized data, conducted meta-analyses, and graded conclusion statements. The second in a two-part series, this article specifically summarizes evidence from RCTs that examined health outcomes (ie, quality of life, disease incidence and prevention of disease progression, or mortality), intermediate health outcomes (ie, anthropometric measures, body composition, or relevant laboratory measures routinely collected in practice), and adverse events as reported by study authors. Analysis of 11 articles from nine RCTs resulted in 16 graded conclusion statements. Among participants with nonalcoholic fatty liver disease, a diet tailored to genotype resulted in a greater reduction of percent body fat compared with a customary diet for nonalcoholic fatty liver disease. However, meta-analyses for the outcomes of total cholesterol, low-density lipoprotein cholesterol, body mass index, and weight yielded null results. Heterogeneity between studies and low certainty of evidence precluded development of strong conclusions about the incorporation of genetic information into nutrition practice. Although there are still relatively few well-designed RCTs to inform integration of genetic information into the Nutrition Care Process, the field of nutritional genomics is evolving rapidly, and gaps in the literature identified by this systematic review can inform future studies. Ellis A, Rozga M, Braakhuis A, Monnard CR, Robinson K, Sinley R, Wanner A, Vargas AJ. J Acad Nutr Diet. S2212-2672(20)30163-5. doi: 10.1016/j.jand.2020.02.009     
  • Scoping Review Project Team and Disclosures (2017-2018)

    The following individuals contributed their valuable time and expertise to the Nutritional Genomics Scoping Review:

    Project Team

    • Mary Rozga, PhD, RDN, Project Manager
      Nutrition Researcher, Academy of Nutrition and Dietetics, Chicago, IL, USA
    • Deepa Handu, PhD, RDN, Methodologist
      Senior Scientist, Academy of Nutrition and Dietetics, Chicago, IL, USA
    • Margaret J. Foster, MLIS, MPH, Medical Librarian
      Associate Professor, Texas A&M University, College Station, TX, USA


    Content Advisors

    • Ginger Hultin, MS, RDN, CSCO
      Registered Dietitian Coach and Team Lead, Arivale, Seattle, WA, USA
    • Catriona R. Monnard, PhD, RDN
      Postdoctoral Researcher, University of Fribourg, Fribourg, Switzerland
    • Ashley J. Vargas, PhD, MPH, RDN, FAND
      Scientist, National Institutes of Health, North Bethesda, MD, USA


    Financial Contributors

    •  Dietitians in Integrative and Functional Medicine Dietetic Practice Group
    • Academy of Nutrition and Dietetics Foundation
    • Academy of Nutrition and Dietetics

    Disclosures of Potential Conflicts of Interest: In the interest of full disclosure, the Academy has adopted the policy of revealing relationships workgroup members and content advisors have with companies that sell products or services that are relevant to this topic. Workgroup members and content advisors are required to disclose potential conflicts of interest by completing the Academy Conflict of Interest Form. It should not be assumed that these financial interests will have adverse impact on the content, but they are noted here to fully inform readers:

    • None of the content advisors listed above disclosed potential conflicts.