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Address correspondence to: Justine R. Horne, PhD, RD, Centre Nutrition, Santé et Société, Institut sur la nutrition et les aliments fonctionnels, Université Laval, 2440 Hochelaga Blvd, Quebec, QC, Canada G1V 0A6.
Address correspondence to: David M. Mutch, PhD, Human Health and Nutritional Sciences, University of Guelph, Guelph, 50 Stone Rd E, Guelph, ON, Canada N1G 2W1.
Health care providers (HCPs) globally, including dietitians, are encountering genetic testing for personalized nutrition (ie, nutrigenomics) in their clinical practice. Although considerable basic research examining diet–gene interactions exists in the literature, comparatively less knowledge is available regarding the use of nutrigenomics in clinical practice to alter dietary outcomes. Despite this, patients are bringing direct-to-consumer nutrigenomics reports to HCPs for interpretation, and more HCPs are now offering nutrigenomics tests to their patients. However, HCPs currently lack clinical guidance documents in nutrigenomics and several steps are needed before full clinical practice guidelines are developed. As a first step in these efforts, our objective was to develop a care map to provide HCPs with a tool for considering nutrigenomics in clinical practice based on the current state of knowledge. An Expert Advisory Panel consisting of 6 nutrigenomics researchers, 3 of whom are also registered dietitians (RDs), developed a care map draft while consulting nutrigenomics literature and incorporating the 3 key pillars of personalized nutrition. To optimize generalizability, the draft was reviewed by 12 HCPs with representation from 6 continents (Africa, Asia, Australia, Europe, North America, and South America) who have experience using nutrigenomics in their clinical practice. The Expert Advisory Panel revised the care map based on HCP feedback and all members of the Expert Advisory Panel approved the final version. A 4-step care map was developed, with sections related to HCP training in nutrigenomics (Step 1), patient screening, assessment and informed consent (Step 2), providing nutrigenomics in clinical practice (Step 3), and patient follow-up (Step 4). Continuing education was incorporated throughout the care map. A nutrigenomics care map was successfully developed and should be used as a starting point to guide clinical practice. This care map is generalizable to dietetics practice globally.
The National Institutes of Health defines precision (personalized) nutrition as a framework that is focused on a number of features relevant to individual and population health including genetics, dietary habits, socioeconomic status, and the microbiome, among others.
The concept of personalized nutrition in the scientific community can encompass the use of blood biomarkers, genetics, epigenetics, protein abundance, metabolites, and the gut microbiome to tailor nutrition recommendations with the aim of improving an individual’s health. The increasing availability and affordability of genetic testing has prompted many consumers to purchase direct-to-consumer (DTC) genetic tests and bring these reports to their HCPs for interpretation. Furthermore, this has prompted several HCPs to incorporate genetic testing into their practice.
and the Academy of Nutrition and Dietetics’ (Academy) 2017 Visioning Report stated that, with respect to personalized nutrition, RDs “can assume an increasingly important role in the emerging health care system that focuses on a genetic predisposition model of health and disease, disease prevention, and integrative health care.”
More recently. The Academy’s consensus statement indicated that “registered dietitian nutritionists are in a position to establish themselves as objective experts in utilizing [nutrigenomics] to individualize care by remaining transparent about existing evidence, applying clinical expertise and training, and participating in research where possible.”
However, the practical use of nutrigenomics as a tool to optimize diet and health outcomes remains a topic of debate due, in part, to a lack of established clinical guideline documents.
For example, the Academy’s consensus statement indicated that there is currently insufficient evidence, particularly from randomized controlled trials, regarding the effectiveness of incorporating nutrigenomic testing into nutrition care.
However, a recent systematic review of randomized controlled trials concluded that personalized nutrition interventions (including those that are based on genetics) can enhance dietary behavior changes to a greater extent than standard population-based advice.
Despite this ongoing debate, nutrigenomics is becoming more common in clinical practice, with research suggesting generally positive attitudes toward this area of nutrition by HCPs and patients alike.
Exploring knowledge and attitudes of personal nutrigenomics testing among dietetic students and its value as a component of dietetic education and practice.
The application of genetics and nutritional genomics in practice: An international survey of knowledge, involvement and confidence among dietitians in the US, Australia and the UK.
Although attitudes toward nutrigenomics are generally positive and nutrigenomics is already a component of clinical practice for many practicing HCPs, concerns have been raised about the lack of industry regulation and scientific validity of some nutrigenomics tests.
A critical examination of legal and ethical considerations for nutrigenetic testing with recommendations for improving regulation in Canada: From science to consumer. J Law Biosci.
In addition, more research is needed to better assess the impact of incorporating genetic testing into nutrition counseling for improving dietary intake and health outcomes.
Effect of incorporating genetic testing results into nutrition counseling and care on dietary intake: An evidence analysis center systematic review—Part I. J Acad Nutri Diet.
Effect of incorporating genetic testing results into nutrition counseling and care on health outcomes: An evidence analysis center systematic review—Part II. J Acad Nutri Diet.
The application of genetics and nutritional genomics in practice: An international survey of knowledge, involvement and confidence among dietitians in the US, Australia and the UK.
The application of genetics and nutritional genomics in practice: An international survey of knowledge, involvement and confidence among dietitians in the US, Australia and the UK.
Success of a genetics educational intervention for nursing and dietetic students: A model for incorporating genetics into nursing and allied health curricula.
With the current reality of nutrigenomics being an increasingly more common component of dietetics practice (either through patients bringing DTC results to their consultations or through HCPs offering nutrigenomics testing in their practice), guiding HCPs toward ethical practice is essential. Therefore, clinical guidance documents for HCPs are needed.
Care maps are valuable starting points that provide useful templates and guidance
Although nutrigenomics is becoming more common in clinical practice, a care map has not been developed for nutrigenomics in health care settings. The purpose of this care map is to provide a tool for the nutrigenomics process in clinical practice for adult patients. Of note, the present care map builds directly on the Academy’s recent consensus statement on incorporating genetic testing into dietetics practice, as well as the position statement of the Academy on nutritional genomics.
The Expert Advisory Panel consisted of 6 nutrigenomics researchers, 3 of whom are also RDs. One of the RDs previously used nutrigenomics in her clinical practice. This Panel developed the draft of the care map based on brainstorming sessions of potential options at each decision point, consideration of health behavior change (see details below), personal clinical experience, and consideration of peer-reviewed literature deemed most relevant to the development of the care map. The key priority of this care map was to provide guidance to HCPs who choose to offer nutrigenomics in clinical practice and/or who are presented with DTC nutrigenomics reports from patients. In addition to consideration of nutrigenomics, which is 1 of the 3 key pillars of personalized nutrition,
based on factors such as age, sex, and social determinants of health, as well as individualized nutrition recommendations based on phenotypes. Therefore, all 3 pillars of personalized nutrition were accounted for during care map development. More specifically, according to the International Society of Nutrigenetics and Nutrigenomics, these pillars include the following: general nutrition recommendations based on population-based studies for various age groups, sex, and social determinants of health; individualized nutrition recommendations based on phenotype (eg, anthropometric, biochemical, clinical examination data); and genetic-based recommendations for personalized nutrition.
The Expert Advisory Panel provided additional feedback throughout revisions of the draft and approved the final version of the care map.
Consideration of Facilitating Health Behavior Change
Providing nutrition care in clinical practice should follow the Nutrition Care Process model, which includes the consideration of optimizing behavior change related to nutrition.
An assessment tool for evaluating the quality of nutrigenomics interventions, based on the format of the National Institutes of Health’s Study Quality Assessment Tools, was developed previously
A systematic review of genetic testing and lifestyle behaviour change: Are we using high-quality genetic interventions and considering behaviour change theory?.
and, to our knowledge, is the only tool that is currently available in this area. This assessment tool was established based on literature identifying strengths and limitations related to nutrigenomics, genetic testing, and health risk messages.
The 5 discrete components of this assessment tool were used to develop the core structure of the care map. These components considered the following: the involvement of HCPs in the interpretation of results, provision of actionable genetic results, providing a copy of reports for patients, ensuring patient comprehension, and patient follow-up.
A systematic review of genetic testing and lifestyle behaviour change: Are we using high-quality genetic interventions and considering behaviour change theory?.
Peer Review by HCPs Using Nutrigenomics in Practice
HCP peer reviewers were identified through convenience sampling within the Expert Advisory Panel’s broad professional network, followed by snowball sampling from the HCPs’ networks. The Expert Advisory Panel contacted HCPs from 6 continents (via e-mail) who had experience using nutrigenomics in their clinical practice. HCP peer reviewers were asked to provide any feedback related to face validity, accuracy, and completeness, with particular attention on whether the care map was easy to follow; whether the care map provided an accurate account of how to best incorporate nutrigenomics into practice; and whether there were any flaws or pitfalls in the care map. Twelve HCPs with representation from 6 different continents (Africa, Asia, Australia, Europe, North America, and South America) reviewed the care map and supporting text for face validity, accuracy, and completeness, and provided the Expert Advisory Panel with feedback on the draft. Responses were open-ended and were returned to the Expert Advisory Panel via e-mail. Ten of the HCPs were RDs, 1 was previously an RD, and 1 was a molecular geneticist. Feedback was used to develop the final care map. The HCP peer review process took approximately 3 months to complete.
Care Map Overview
A 4-step nutrigenomics care map was developed, with ongoing continuing education essential throughout the clinical process. The final nutrigenomics care map is presented in the Figure, with a case study example detailed in Box 1, Box 2, Box 3, Box 4. It is important to note that as knowledge regarding the impact of genetic testing in clinical practice continues to evolve, we anticipate that this first iteration of the nutrigenomics care map will be updated accordingly.
FigureNutrigenomics care map. DTC = direct-to-consumer; HCP = health care provider; SMART = specific, measurable, attainable, relevant, and time-based.
Given that nutrigenomics is a specialized area, specific education and training are needed for HCPs. This area of nutrition has unique legal and ethical considerations, which we encourage HCPs to learn more about through further reading.
These considerations relate to topics including informed consent, the nature of the genetic test (ie, the type of results, such as those that relate to weight, food intolerances, and athletic performance), implications of the genetic variants tested (eg, pleiotropic effects in which a genetic variant has nutrigenomics implications but also disease risk implications
Notably, clinical practice guidelines (CPGs) do not yet exist for nutrigenomics. CPGs are important to clinical practice, as they help to provide a clear summary of evidence available to inform a particular practice question or topic, and contribute to patient-centered care.
With a current absence of CPGs related to nutrigenomics, HCPs must seek training from different sources.
In addition to having a strong background in evidence-based nutrition and ethical health care practices, HCPs should seek to have confidence and competence in their knowledge of basic genetics, legal considerations relevant to genetic testing, and clinical interactions with patients undergoing nutrigenomics testing. Accredited nutrition and dietetics programs provide a strong basis for nutrition knowledge, as well as foundations of cellular and molecular biology,
but additional training in nutrigenomics can be beneficial. To our knowledge, nutrigenomics is not considered a controlled act under provincial/state and national legislation; thus, almost all HCPs (and not just RDs) can provide these genetic tests in their practice, with only a few exceptions. For example, naturopaths in Ontario, Canada, are not permitted to collect saliva samples and order genetic tests
; however, they are still permitted to interpret the results of DTC genetic tests with their clients. RDs, who are regulated HCPs with a strong background knowledge in evidence-based nutrition, are the ideal source of nutrigenomics because they are legally required (and overseen by regulatory bodies) to uphold the highest standards of confidentiality, security of documentation, and ethics.
among others. To our knowledge, none of the current nutrigenomics tests available to patients include information that would be considered diagnostic, but as knowledge continues to advance and new tests become commercially available, this is important for HCPs to consider from a scope of practice perspective. Furthermore, several DTC genetic tests include genetic information related to nutrition, in addition to genetic information related to risk of diseases, where personalized nutrition advice beyond general recommendations for healthy eating may not apply. For example, patients may receive information about BRCA1 and BRCA2 genotype as they relate to breast cancer risk.
In such cases, HCPs practicing in nutrition must recognize that it is outside of their scope of practice to provide health recommendations based on these results and should refer the patient to the appropriate HCP (physician or genetic counselor).
Several resources exist for HCPs to further their knowledge in nutrigenomics, including more than 35 courses offered globally ranging from short online presentations to university-level courses and graduate degrees that are detailed elsewhere.
For HCPs in which nutrigenomics is a component of their practice, available training programs should be assessed for areas where they feel they require more knowledge. For example, peer-reviewed literature can provide insightful information into the ethical considerations specific to nutrigenomics, which can be used to further enhance knowledge in this area.
A critical examination of legal and ethical considerations for nutrigenetic testing with recommendations for improving regulation in Canada: From science to consumer. J Law Biosci.
Guide and position of the International Society of Nutrigenetics/Nutrigenomics on Personalized Nutrition: Part 2—Ethics, challenges and endeavors of precision nutrition.
University-affiliated courses and courses offered by regulatory bodies/professional associations can provide a beneficial combination of education on both the scientific evidence and the practical application of nutrigenomics. Genetic testing companies may provide training materials and representatives for consultation. Although caution is warranted for materials offered by private companies due to the potential for biased representations of the science, HCPs should review the company’s credentials (eg, whether members—researchers and HCPs—of the Scientific Advisory Board have nutrigenomics and evidence-based nutrition training) as an increasing number of scientists and clinicians are involved in the development of companies that provide genetic tests.
Reviewing Nutrigenomics Tests
There are several considerations when reviewing various nutrigenomics tests. These considerations relate to analytic validity; scientific validity; clinical utility; and ethical, legal, and social implications, which have been further discussed at length elsewhere
and are also relevant to the review of DTC nutrigenomics tests that patients may bring to an HCP for interpretation. Analytic validity refers to the accuracy of genotyping, scientific validity refers to the strength of the scientific evidence for gene-diet interactions, and clinical utility refers to the potential for the information (and subsequent advice) to promote beneficial dietary changes and positive health-related outcomes.
These topics have been discussed at length elsewhere; we direct HCPs to these works to gain a deeper understanding of validity and utility related to nutrigenomics.
It is important to note that if a test does not have analytic validity, scientific validity, and clinical utility for the patient, it should not be used in clinical practice.
To help ensure analytic validity, accredited laboratories should be used for the genetic analysis. Laboratory accreditation processes differ from one country to another. For example, the United States has strict regulations for all laboratories, whereas in Canada the accreditation and regulatory processes vary from province to province.
A critical examination of legal and ethical considerations for nutrigenetic testing with recommendations for improving regulation in Canada: From science to consumer. J Law Biosci.
HCPs should further be aware of whether the company shares genetic information and data with third-party companies, and this should be included in the informed consent process (as discussed in Step 2).
The scientific validity of consumer genetic information and nutrigenomics testing is sometimes criticized, with critics suggesting a lack of evidence for demonstrated genetic differences in biologic changes after a dietary intervention.
Fine mapping of genome-wide association study signals to identify genetic markers of the plasma triglyceride response to an omega-3 fatty acid supplementation.
As more clinical trials using nutrigenomics are conducted, systematic reviews of this research will further clarify the impact of using genetic information in practice to modify dietary outcomes. However, it is important to acknowledge that even population-based dietary recommendations are created from the highest level of available evidence, for which intervention studies are often not available.
With respect to clinical utility, growing evidence indicates that DNA-based dietary recommendations may motivate positive dietary changes, which is an important component of clinical utility that warrants consideration for the use of evidence-based nutrigenomics tests in practice.
A systematic review of genetic testing and lifestyle behaviour change: Are we using high-quality genetic interventions and considering behaviour change theory?.
Enhanced long-term dietary change and adherence in a nutrigenomics-guided intervention compared to a population-based (GLB/DPP) lifestyle intervention for weight management: Results from the NOW randomized controlled trial.
(Corresponding to Care Map Step 1): HCP Preparation (Case Study)
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An HCP has completed an accredited undergraduate program in nutrition and dietetics, and a dietetics internship, and owns a private practice. They are interested in providing nutrigenomics testing to their patients.
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Because of their background education, they feel competent in their knowledge on the basics of nutrition and genetics. Thus, they seek out training in the areas of ethics, evidence-based nutrigenomics interactions, and the application of nutrigenomics in clinical practice.
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To better understand ethical considerations of nutrigenomics, they decide to review 2 scientific articles (eg, Hurlimann and colleagues
In order to improve their knowledge on the science of nutrigenomics, they review the available training opportunities and decide to enroll in a course at an academic institution (eg, Collins and colleagues
They also review the present care map to assist in planning to incorporate nutrigenomics into their practice.
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When selecting which nutrigenomics test to use, they carefully consider the scientific validity, clinical utility, and nature of the test.
Step 2: Patient Screening, Assessment, and Informed Consent
Screening and Nutrition/Health Assessment
First, it should be reinforced that the purpose of this care map is to guide the personalized nutrition process in clinical practice in adult patients, given that there are different considerations for pediatric patients. In cases where the HCP offers nutrigenomics in their clinical practice, before undergoing nutrigenomics testing, all patients should be screened to identify potential contraindications for nutrigenomics testing (eg, patients with eating disorders for tests with weight-loss response results; patients with low income who may not be willing/able to afford this testing). The HCP also has a responsibility to consider cost–benefit of genetic testing, taking into account the patient’s reasons for wanting to pursue testing, financial willingness and ability, and health status/family history. When cost–benefit justification is not met, or there is no evidence to support the use of a particular genetic test in a subset of the population, or significant contraindications exist, then the HCP has a responsibility to advise the patient against proceeding with nutrigenomics testing. The screening process may happen in person during a patient appointment, or the HCP may send the patient an assessment form to better understand the patient’s anthropometric, biochemical, clinical, and dietary intake data. The screening and assessment process can also be an opportune time to identify health considerations that could impact general nutrition recommendations, such as food allergies, chronic kidney disease, or type 2 diabetes. These may impact some of the recommendations detailed in the nutrigenomics report. Furthermore, this is a beneficial time to identify the patient’s health and nutrition goals and establish priorities. In addition, the HCP should consider key determinants of behavior change and validated behavioral theories (eg, see Prochaska and Velicer
), and use this information to help guide their counseling to promote behavior change. Based on this assessment, the HCP should determine whether nutrigenomics testing is appropriate for the patient, or if a personalized nutrition plan that does not incorporate genetic information is sufficient (eg, see Celis-Morales and colleauges
Design and baseline characteristics of the Food4Me study: A web-based randomised controlled trial of personalised nutrition in seven European countries.
). For example, HCPs may wish to exercise caution in the decision to pursue certain nutrigenomics tests for patients with eating disorders (eg, some tests include information on weight loss) and ensure that the potential benefits of the information for the patient outweigh potential harms, based on established counseling guidelines for eating disorders.
If nutrigenomics is determined to be appropriate, the HCP should explain the nature of the test to the patient and determine whether the test will meet the patient’s expectations. If yes, then the HCP proceeds to the informed consent process if the patient wishes to undergo nutrigenomics testing. In some cases, a patient may be more interested in medical genetics or pharmacogenomics and a referral to the appropriate HCP is advisable if this work is outside of the nutrition HCP’s scope of practice.
Detailed information about the recommended informed consent process for nutrigenomics has been detailed elsewhere.
Although DTC companies have informed consent processes at time of purchase, when genetic testing is done through HCPs, the HCP is responsible for obtaining the informed consent from all patients before they undergo nutrigenomics testing. The HCP should keep a copy of the signed consent form in the patient’s chart, and the patient should also receive a copy. The consent process should include information related to the nature of the test and recommendations, pros and cons of the test, information related to privacy, potential added value to the nutrition care plan, and legal implications, such as the potential for genetic discrimination in some countries
Some HCPs may choose to de-identify patients (and instead use codes in place of names) when using online company platforms to link test kits to patient results; these codes are then linked to the patient’s names in their own files but are not visible to the company. This practice is intended to provide an additional level of security and confidentiality of the patients’ genetic information.
(Corresponding to Care Map Step 2): Patient Screening, Assessment and Informed Consent (Case Study)
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The HCP is now prepared to incorporate nutrigenomics into their practice. During an initial assessment, patient “JD” expresses interest in undergoing nutrigenomics testing.
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Based on the initial assessment, the HCP does not identify any contraindications to proceeding with this test.
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JD identified cardiovascular disease management and prevention as an area of health priority. JD is taking medication for hypertension and their recent blood work demonstrated elevated triglyceride levels of 4.2 mmol/L (to convert mmol/L triglycerides to mg/dL, multiply mmol/L by 88.6). JD has a strong family history of myocardial infarction and dyslipidemia. They also have a personal history of recurring calcium oxalate kidney stones. The HCP sees potential added value to the nutrition care plan if the patient were to receive genetically guided nutrition advice.
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Therefore, the HCP proceeds with completing written informed consent with JD, who agrees and signs a consent document that is kept in their secure chart.
Step 3: Providing Nutrigenomics In Clinical Practice
Appointments with Patient to Collect Sample and/or Review Results
When the HCP is offering nutrigenomics in their practice, a DNA sample (typically saliva or buccal swab) is collected and sent for genetic analysis. This process has been outlined in detail elsewhere.
A critical examination of legal and ethical considerations for nutrigenetic testing with recommendations for improving regulation in Canada: From science to consumer. J Law Biosci.
Companies may have specific instructions for collecting the sample, such as avoiding eating or smoking 30 minutes before sample collection. The length of time between the sample collection and follow-up appointment is dependent on the amount of time needed for the nutrigenomics testing company to analyze the sample and send the report to the HCP.
When preparing for the appointment to communicate or review nutrigenomics results, the HCP should review the patient’s results on their own to ensure their comprehension. If the HCP requires clarification about any component of the report, they should consult the scientific literature or potentially contact the company for clarification. It is acknowledged that although reviewing scientific literature is ideal, it can be both challenging and time-consuming, reinforcing the importance of adequate training and the need for CPGs among HCPs who wish to offer nutrigenomics tests.
HCPs should use a patient-centered approach for the appointment in which nutrigenomics results are disclosed and reviewed. In some cases, multiple appointments to review the results may be warranted, especially as knowledge in the field continues to grow and nutrigenomics tests include more and more information. Therefore, setting priorities is of great importance to the nutrigenomics care process and, more generally, the nutrition care process.
Indeed, the HCP should consider phenotype and/or blood work results in conjunction with nutrigenomics results. For example, if a patient’s nutrigenomics report indicates an elevated risk for lactose intolerance but the patient exhibits no signs or symptoms of gastrointestinal discomfort, then it may be unnecessary for the patient to limit their intake of lactose-containing products. In addition, in cases where a genetic report includes information that is outside of the HCP’s scope of practice (eg, BRCA1/2 genetic testing for breast cancer risk), they should refer the patient to the appropriate HCP for interpretation of such results.
To begin the appointment, the HCP should start by providing an explanation of basic information about genetics so that the patient can understand the different components of the report (although some HCPs may choose to provide this information during the informed consent meeting). Specifically, the HCP should provide an overview of how genes play a role in nutrition (eg, metabolism, absorption, and taste preferences), genetic variants/genotypes and how these differ from person to person, and other relevant genetic-related information appearing in the nutrigenomics test report that an HCP would not expect a patient to understand (eg, genes and alleles). The HCP should also explain where to find different information throughout the report, so that the patient can easily review this information, as needed, after the appointment. When reviewing the results, the HCP may need to adjust some nutrition recommendations based on individualized patient considerations (eg, food allergies/restrictions or disease). In addition, patients should be aware that their health may change over time and, as such, nutrition recommendations may also change. To help ensure patient comprehension, it is important to use simple language and repeatedly check-in with the patient to ask whether they have any questions, or whether they would like specific sections revisited/repeated. Different counseling techniques can be used in an effort to optimize understanding. For example, the test–feedback approach and teach-back method have been shown to improve patients’ comprehension of information presented in appointments with HCPs.
Patient comprehension also includes ensuring that the patient understands practical strategies to help achieve the nutrigenomics recommendations suggested in the report. At the end of the session, the HCP and patient should work together to identify 1 to 3 specific, measurable, attainable, relevant, and time-based (SMART) goals
for the patient to focus on. Additional resources, such as recipes, handouts, and digital tools (including apps), can also be provided or recommended to the patient as needed. HCPs may further recommend that patients complete specific laboratory tests for biomarkers relevant to the patient’s nutrigenomics report. Overall, the HCP should allot approximately 60 minutes for this first nutrigenomics review session. Including follow-up appointments for further review is an important component of the nutrition care process for nutrigenomics, but also for general nutrition counseling.
This guidance is intended for a scenario of nutrigenomics testing being offered in practice; however, it is becoming more common for patients to visit an HCP with raw genetic information or DTC reports in hand. Before reviewing reports, HCPs should advise patients about the variable scientific validity of DTC tests resulting in part from lack of industry regulation.
A critical examination of legal and ethical considerations for nutrigenetic testing with recommendations for improving regulation in Canada: From science to consumer. J Law Biosci.
Some patients may make use of raw genetic data to generate nutrigenomics-related information that was not part of the original test results, as various software is available online to perform this kind of analysis.
(Corresponding to Care Map Step 3): Providing Nutrigenomics in Clinical Practice (Case Study)
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The HCP collects a saliva sample from JD, sends it to the testing company, and books a follow-up appointment 3 weeks after JD’s initial assessment. The HCP and JD discuss what results they will give priority to in their follow-up appointment.
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When the HCP receives the report, they determine (based on JD’s initial assessment) that special consideration related to some of the recommendations outlined in the nutrigenomics report will require adjustments; JD has special dietary considerations related to dietary calcium, sodium, and high oxalate foods given their recurring calcium oxalate kidney stones. As identified during JD’s initial appointment, cardiovascular disease prevention is a priority for the patient. Therefore, this is the focus of the appointment.
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At the follow-up appointment, the HCP provides JD with an overview of genetics and then reviews the results from the nutrigenomics report, while spending extra time and attention on sections relevant to cardiovascular health.
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The HCP checks in with JD throughout the appointment, to ensure the patient understands the report. They use the test–feedback method in their counseling. JD asks for further clarification about which foods contain α-linolenic, eicosapentaenoic, and/or docosahexaenoic n-3 fatty acids (the patient has the GG genotype of FADS1 rs174537), so the HCP reviews this section of the report again.
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At the end of the appointment, JD sets 3 SMART goals, with the help of the HCP. These goals are developed based on the results of the nutrigenomics test in addition to the patient’s personal general nutrition and health assessment. Starting today, JD plans to:
1.
Continue including 1 egg at breakfast 5 days of the week, but switch to n-3 eggs cooked in 1 Tbsp canola oil and add 1 Tbsp ground flaxseed to yogurt
2.
Eat 3 oz of salmon, for 3 meals this week
3.
Review the cardiovascular health sections of the nutrigenomics report over the next 2 weeks
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The HCP provides JD with a copy of the nutrigenomics report and they decide to book a follow-up appointment in 3 weeks to review JD’s progress with their goals and to potentially set new SMART goals.
Step 4: Patient Follow-Up
Follow-up appointments are ideal for optimizing patient comprehension, as well as for monitoring/assessing nutrition behavior change and health. Indeed, a single intervention session is less likely to facilitate behavior change.
Therefore, it is recommended that the patient book at least 1 follow-up appointment. In many cases, patients are seeing a fee-for-service HCP and paying for nutrigenomics tests; thus, cost–benefit considerations must be made throughout the nutrigenomics care process. The purpose of a follow-up appointment is to review the patient’s progress (with respect to nutrition habits and changes in any measured biomarkers), answer any questions the patient may have, review priority areas of nutrition care, review SMART goals set in the previous session, and set new SMART goals if the patient is ready. The number and duration of follow-up appointments required should be decided between the HCP and the patient based on the patient’s needs and wants. If a patient declines immediate follow-up, the HCP should ensure that the patient has the appropriate contact information in case they decide to book an appointment at a later date, and should ensure that the patient is aware that they can return for follow-up at any time. Follow-up data (eg, changes in nutrition or biomarkers) can also be used to inform in-house research for the HCP’s practice.
(Corresponding to Care Map Step 4): Patient Follow-Up (Case Study)
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JD returns for their follow-up appointment. JD has achieved all of their SMART goals!
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JD brings a list of questions related to the basics of genetics, and brings up another question about the result from their nutrigenomics test related to caffeine and the CYP1A2 genotype. The HCP reviews the information on the basics of genetics and clarifies the nutritional implications of JD possessing the AA genotype of CYP1A2 (rs2472300). They use the teach-back method to help ensure that they are providing an explanation that JD understands.
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Based on this discussion, JD decides to set 1 new SMART goal; they aim to limit caffeine intake to the equivalent of 2 cups (500 mL) of coffee per day. JD is confident that they will be able to achieve this goal, but is hesitant to set other additional new goals at this point in time.
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JD books another follow-up appointment in 3 weeks to provide a source of accountability.
Discussion
To our knowledge, this is the first care map in the field of nutrigenomics. This article advocates neither for nor against the use of nutrigenomics in clinical practice. Rather, this care map represents a practical tool that should be used by HCPs who are using nutrigenomics in their clinical practice or who are considering doing so. It should also be used by HCPs who experience patients that bring genetic testing results obtained elsewhere to their appointments for interpretation.
The development of this care map was deemed of high importance, given the current reality that patients, researchers, and HCPs are highly interested in personalized nutrition.
Care maps have been developed and used successfully in many areas of health care, such as metabolic syndrome, dyslipidemia, family-centered care, chronic disease prevention, and screening, as well as surgical care.
Developing clinical decision tools to implement chronic disease prevention and screening in primary care: The BETTER 2 program (building on existing tools to improve chronic disease prevention and screening in primary care).
In some regards, this nutrigenomics care map is more complex than others, given that the field of nutrigenomics has unique considerations and is an evolving area. These considerations relate to HCP training, scientific validity of nutrigenomics tests, regulation, and others, and have been outlined throughout this work and elsewhere.
In comparison to care maps in other areas of health care, this nutrigenomics care map differs in that there are 4 concrete steps involved, with the first step typically completed only once by the HCP, and steps 2 to 4 completed with each new patient. This care map represents the first tool for the use of nutrigenomics in practice; however, we anticipate that updates to this care map will be required as both the basic science and evidence regarding clinical uptake progress. This care map was developed through expert consensus, which is considered lower-level evidence,
and future research should assess the use of this care map in clinical practice. Furthermore, we acknowledge that this care map represents a first step toward the development of CPGs. In order to develop CPGs for nutrigenomics, more systematic reviews of gene–diet interactions are needed. These reviews should include an evidence grading method and should follow established CPG methodology, such as the use of AGREE II instrument.
These systematic reviews can ascertain whether the evidence for individual diet–gene interactions is low, moderate, or high quality, for example, through the use of the GRADE (Grading of Recommendations, Assessment, Development and Evaluation) approach.
We anticipate that such reviews will clarify discussions about scientific validity and help determine whether specific gene–diet interactions are ready for clinical practice. As knowledge continues to advance, this nutrigenomics care map will need to be updated to continue providing the most up-to-date guidance for HCPs. In the meantime, the lack of clinical guidance documents (such as CPGs) has not prevented HCPs from already incorporating nutrigenomics in practice. Therefore, we deemed it necessary and beneficial to develop a practical tool based on current knowledge in the field that will help HCPs use nutrigenomics with their patients in a way that promotes evidence-based, ethical practice.
As research continues in this area, new discoveries in nutrigenomics will be realized. This may include the discovery of new genetic variants with implications for nutrition and health, as well as the development of polygenic nutrigenomic information that moves beyond single genes and considers numerous genes that influence a single nutrition-related outcome. Although the present care map provides important insights for nutrigenomics in HCPs’ practice, there remains a clear need to develop CPGs in the field of nutrigenomics to better assist practitioners in assessing the scientific validity of nutrigenomics tests available on the market. This is a priority future research endeavor.
Conclusions
This first nutrigenomics care map can be used globally as a tool for HCPs encountering or incorporating nutrigenomics in their practice. Overall, this care map provides a first step toward facilitating best practice in the field of nutrigenomics. It is anticipated that this care map will be revised and updated as research in the field continues to evolve and this area of clinical practice matures. Nevertheless, as the general population becomes more interested in personalized nutrition and the cost of genetic testing continues to decrease, the present care map will become increasingly important for HCPs, researchers, and ultimately, patient care.
Acknowledgements
The authors would like to thank the following HCPs for critically reviewing the care map figure and associated text and providing valuable feedback: Mariette Abrahams, PhD, RD (England), Melissa Adamski, MND, APD, PhD (candidate) (Australia), Chelsea Bezerra, RD (Brazil), Jerusa Brignardello, MSc, RD, PhD (candidate) (England, Chile), Flavia Fayet-Moore, PhD, MND, APD (Australia), Julie Freeman, MA, RD, LDN (United States), Denise Furness, PhD (Australia), Nicqui Grant, RD (South Africa), Yael Joffe, PhD, RD, FACN (South Africa), Paige McDonald, MScFN, RD (Canada), Marina Pioltine (Brazil), MSc, RD and Janani Tamilvanan, MSc, MPhil, PhD (candidate) (India). All HCP peer reviewers who were involved in critically reviewing the care map have current or previous experience offering nutrigenomics testing in their clinical practice. This was deemed essential to obtain feedback regarding the current reality that HCPs are already using and/or encountering genetic testing in nutrition practice.
Author Contributions
All authors helped to conceptualize and design the study. J. R. Horne and D. M. Mutch drafted the manuscript and were responsible for the HCP peer review process with RDs/HCPs. J. R. Horne, D. M. Mutch, J. Madill, D. E. Nielsen, J. Robitaille, and M.-C. Vohl revised manuscript drafts. J. R. Horne and D. M. Mutch had primary responsibility for the final content. All authors reviewed and approved the final manuscript. None of the authors are currently offering nutrigenomics in clinical practice.
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This article was written by J. R. Horne, PhD, RD, postdoctoral fellow, Centre Nutrition, Santé et Société, Institut sur la nutrition et les aliments fonctionnels, Université Laval, Quebec City, Quebec, Canada, and School of Nutrition, Université Laval, Quebec City, Quebec, Canada; at the time of the study, she was a PhD candidate, Health and Rehabilitation Sciences, Western University, London, Ontario, Canada; Daiva E. Nielsen, PhD, Assistant Professor, School of Human Nutrition, McGill University, Montreal, Quebec, Canada; Janet Madill, PhD, RD, FDC, Associate Professor School of Food and Nutritional Sciences, Western University, London, Ontario, Canada; Julie Robitaille, PhD, RD, Full Professor, Centre Nutrition, Santé et Société, Institut sur la nutrition et les aliments fonctionnels, Université Laval, Quebec City, Quebec, Canada, and School of Nutrition, Université Laval, Quebec City, Quebec, Canada; Marie-Claude Vohl, PhD, Full Professor, Centre Nutrition, Santé et Société, Institut sur la nutrition et les aliments fonctionnels, Université Laval, Quebec City, Quebec, Canada, and School of Nutrition, Université Laval, Quebec City, Quebec, Canada; and David M. Mutch, PhD, Associate Professor, Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada.
STATEMENT OF POTENTIAL CONFLICT OF INTEREST No potential conflict of interest was reported by the authors.
FUNDING/SUPPORT M. C. Vohl is a Tier 1 Canada Research Chair in Genomics Applied to Nutrition and Metabolic Health. J.R. Horne was supported through postdoctoral fellowships from the Centre Nutrition, Santé et Société, the Institut sur la nutrition et les aliments fonctionnels, and the Canadian Institutes of Health Research (Doctoral Research and Postdoctoral Fellowship Awards).
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