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Practice Applications Letter to the Editor| Volume 120, ISSUE 12, P1960-1961, December 2020

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Authors’ Response

Published:September 18, 2020DOI:https://doi.org/10.1016/j.jand.2020.07.030
      Thank you very much for your interest in and thoughtful analysis of “Incorporating Genetic Testing into Nutrition Care: Academy of Nutrition and Dietetics Consensus Report Based on Systematic Review” and the supporting systematic reviews.
      • Braakhuis A.
      • Monnard C.R.
      • Ellis A.
      • Rozga M.
      Consensus Report of the Academy of Nutrition and Dietetics: Incorporating genetic testing into nutrition care.
      • Robinson K.
      • Rozga M.
      • Braakhuis A.
      • et al.
      Effect of incorporating genetic testing results into nutrition counseling and care on dietary intake: An evidence analysis center systematic review-part I.
      • Ellis A.
      • Rozga M.
      • Braakhuis A.
      • et al.
      Effect of incorporating genetic testing results into nutrition counseling and care on health outcomes: An evidence analysis center systematic review-part II.
      Discussion of novel personalized nutrition technologies is necessary to improve understanding of how these tools can most effectively be used by registered dietitian nutritionists (RDNs).
      Thank you for the opportunity to address your methodological concerns, because these are likely questions that many RDNs have. The reader is correct that the Academy’s systematic review did use broad inclusion criteria to include 1) interventions that disclosed genetic information only, in addition to 2) those that tailored nutrition advice according to genetic information. The systematic review revealed a dearth of randomized controlled trials that actually tailored actionable nutrition advice based on genotype. Although this was disappointing to the authors as well, it is an important finding that is highlighted in the second systematic review: “Only the Food4Me study and Stachowska et al tailored diet advices according to individual genotype as part of the intervention.”.
      • Ellis A.
      • Rozga M.
      • Braakhuis A.
      • et al.
      Effect of incorporating genetic testing results into nutrition counseling and care on health outcomes: An evidence analysis center systematic review-part II.
      In the systematic reviews, although the interventions themselves were heterogeneous (eg, genes/single-nucleotide polymorphisms examined, intervention procedures), the results, both practically and statistically, had very little heterogeneity. For example, in the systematic review examining dietary intake,
      • Robinson K.
      • Rozga M.
      • Braakhuis A.
      • et al.
      Effect of incorporating genetic testing results into nutrition counseling and care on dietary intake: An evidence analysis center systematic review-part I.
      the forest plots (Figures 5 and 6) show that there were no differences between the intervention and control groups for each of the studies included; thus, there were not significant differences in some studies that were masked by a lack of effect in less intensive interventions. Similarly, in the systematic review for intermediate and health outcomes,
      • Ellis A.
      • Rozga M.
      • Braakhuis A.
      • et al.
      Effect of incorporating genetic testing results into nutrition counseling and care on health outcomes: An evidence analysis center systematic review-part II.
      Figures 2 and 3 show that there was no effect of the intervention in any of the included studies. The one exception to this was for the outcome of body composition, for which the conclusion was: “In participants with NAFLD, there was a greater reduction in percent body fat when results of genetic testing were incorporated into nutrition counseling or care compared with counseling or care that did not incorporate genetic results, but there was no difference in percent lean mass between groups.” This finding was, therefore, not masked with the inclusion of studies that disclosed genetic information only. Transparency in communicating exactly what the intervention entailed in the conclusion statements of the systematic reviews was a high priority during the writing of these statements.
      The supporting systematic reviews included a wide variety of intermediate and health outcomes, and several outcomes considered in the systematic reviews were reported in only one randomized controlled trial. The reader is correct that using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) system, each outcome is independently assessed for evidence quality.
      • Guyatt G.
      • Oxman A.D.
      • Sultan S.
      • et al.
      GRADE guidelines: 11. Making an overall rating of confidence in effect estimates for a single outcome and for all outcomes.
      The number of studies reporting an outcome, the samples sizes of the studies, and several other factors are considered when determining the quality of evidence. Therefore, many of the outcomes were graded as “low/weak” quality evidence. The authors ardently agree with the reader that “low/weak” or “moderate/fair” evidence “does not necessarily imply that nutrigenomics interventions cannot be effective at motivating dietary changes and optimizing nutrition-related health outcomes, but rather that more research is needed.” The authors attempted to communicate this as clearly as possible in the consensus statement, which begins, “There is insufficient evidence from randomized controlled trials regarding the effectiveness of incorporating nutrigenetic testing into nutrition counseling or care and reporting dietary or clinical outcomes at present.” This lack of evidence was also a driving reason behind the decision to write a Consensus Statement from the Academy, which conveys a low strength of evidence.
      • Handu D.
      • Moloney L.
      • Rozga M.R.
      • Cheng F.
      • Wickstrom D.
      • Acosta A.
      Evolving the Academy position paper process: Commitment to evidence-based practice.
      Although evidence at the time of the systematic review did not support an effect of incorporating genetic information on most dietary, intermediate, and health outcomes reported, the authors concluded that it was too soon to make firm conclusions about how genetic information should (or should not) be incorporated into nutrition care, particularly because of the rapid evolution of technologies and available research. As acknowledged in the Consensus Report, some RDNs are already early adopters who are incorporating nutritional genomics into their clinical practice. The goal of the Consensus Report was not to discourage this but rather to provide some practical guidelines to help RDNs evaluate genetic testing companies with whom they partner. The Consensus Report also implored the early adopters to document in Academy of Nutrition and Dietetics Health Informatics Infrastructure (ANDHII) to better establish the evidence base: “Current RDN practitioners using nutrition-related genetic information in their practice should be encouraged to record and document clinical cases in the ANDHII. The analysis of ANDHII data may assist future workgroups in proving an accurate picture of the effectiveness of nutritional genomics, which will only be possible with timely, accurate, and multiple case inputs.”
      Thank you for continuing a discussion on the responsibility of RDNs to remain abreast of current research on nutritional genomics. It may be possible that “health professionals often do not have the time, and some may lack the highly specialized competencies to accomplish this complex task.” One method of addressing this challenge is for practitioners to attend webinars and other trainings and to read systematic reviews and evidence-based practice guidelines on the topic, all of which attempt to translate primary research to inform practice. However, RDNs also should feel confident in their ability to read and understand primary research that applies to clinical practice. Although most RDNs will not be experts in genetics, they are trained to read publications reporting on clinical trials, understand how this research is conducted, and determine whether incorporating genetic information resulted in an improved outcome.
      The Consensus Report describes, “Genetic testing companies may be able to provide evidence regarding the strength of the gene–nutrition association and efficacy when used in practice. In addition, RDNs can rely on systematic reviews and high-quality research studies to determine whether the genes/genetic test in question has demonstrated efficacy in practice.” Possibly some genetic testing companies could be biased in the evidence they provide to support their tests, and RDNs should consider conflicts of interest when reviewing the evidence provided. However, this evidence can be used as a starting point to determine whether the company does have evidence to support efficacy in practice or whether the tests in question rely on association studies only, which may not be applicable for a practitioner.
      One additional element to highlight, and that was highlighted in the Consensus Report and supporting systematic reviews, is the rapid evolution of technology and research in the field of nutritional genomics. The systematic reviews supporting this Consensus Report were conducted with evidence published until December 2018. Thus, research using more advanced methods, such as consideration of the polygenic nature of many diseases, may already be changing the picture of what we know. Summarizing the evidence on this topic at regular intervals moving forward will be important.
      Thank you for your consideration of and insight on the discussed systematic reviews and Consensus Report.

      References

        • Braakhuis A.
        • Monnard C.R.
        • Ellis A.
        • Rozga M.
        Consensus Report of the Academy of Nutrition and Dietetics: Incorporating genetic testing into nutrition care.
        J Acad Nutr Diet. 2020; https://doi.org/10.1016/j.jand.2020.04.002
        • Robinson K.
        • Rozga M.
        • Braakhuis A.
        • et al.
        Effect of incorporating genetic testing results into nutrition counseling and care on dietary intake: An evidence analysis center systematic review-part I.
        J Acad Nutr Diet. 2020; https://doi.org/10.1016/j.jand.2020.04.001
        • Ellis A.
        • Rozga M.
        • Braakhuis A.
        • et al.
        Effect of incorporating genetic testing results into nutrition counseling and care on health outcomes: An evidence analysis center systematic review-part II.
        J Acad Nutr Diet. 2020; https://doi.org/10.1016/j.jand.2020.02.009
        • Guyatt G.
        • Oxman A.D.
        • Sultan S.
        • et al.
        GRADE guidelines: 11. Making an overall rating of confidence in effect estimates for a single outcome and for all outcomes.
        J Clin Epidemiol. 2013; 66: 151-157
        • Handu D.
        • Moloney L.
        • Rozga M.R.
        • Cheng F.
        • Wickstrom D.
        • Acosta A.
        Evolving the Academy position paper process: Commitment to evidence-based practice.
        J Acad Nutr Diet. 2018; 118: 1743-1746

      Linked Article

      • Response to the Consensus Report of the Academy of Nutrition and Dietetics: Incorporating Genetic Testing into Nutrition Care
        Journal of the Academy of Nutrition and DieteticsVol. 120Issue 12
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          It is our pleasure to engage with the Academy of Nutrition and Dietetics in this important discussion on the impact of incorporating genetic testing into nutrition care. We reviewed, with interest, the Academy’s Consensus Report and companion papers detailing the conducted scoping and systematic reviews on the impact of genetic testing on dietary change and health outcomes.1-4 This work is of great importance, and we applaud the authors for encouraging registered dietitians to become involved in the research process1 in an effort to optimize pragmatic research in precision nutrition.
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