Nutrigenomics and metabolomics will change clinical nutrition and public health practice: insights from studies on dietary requirements for choline

Science is beginning to understand how genetic variation and epigenetic events alter requirements for, and responses to, nutrients (nutrigenomics). At the same time, methods for profiling almost all of the products of metabolism in a single sample of blood or urine are being developed (metabolomics). Relations between diet and nutrigenomic and metabolomic profiles and between those profiles and health have become important components of research that could change clinical practice in nutrition. Most nutrition studies assume that all persons have average dietary requirements, and the studies often do not plan for a large subset of subjects who differ in requirements for a nutrient. Large variances in responses that occur when such a population exists can result in statistical analyses that argue for a null effect. If nutrition studies could better identify responders and differentiate them from nonresponders on the basis of nutrigenomic or metabolomic profiles, the sensitivity to detect differences between groups could be greatly increased, and the resulting dietary recommendations could be appropriately targeted. It is not certain that nutrition will be the clinical specialty primarily responsible for nutrigenomics or metabolomics, because other disciplines currently dominate the development of portions of these fields. However, nutrition scientists' depth of understanding of human metabolism can be used to establish a role in the research and clinical programs that will arise from nutrigenomic and metabolomic profiling. Investments made today in training programs and in research methods could ensure a new foundation for clinical nutrition in the future.     

Probiotics and prebiotics in dietetics practice

Probiotics and prebiotics share a unique role in human nutrition, largely centering on manipulation of populations or activities of the bacteria that colonize our bodies. Benefits of regular consumption of probiotics or prebiotics include enhanced immune function, improved colonic integrity, decreased incidence and duration of intestinal infections, down-regulated allergic response, and improved digestion and elimination. Research has shown that probiotics and prebiotics may be useful in achieving these and other positive effects, provided that proper strain, product selection, and dosing guidelines of commercial products are followed. There is a need to consolidate the basic and applied research on probiotics and prebiotics into useful tools for food and nutrition professionals. Information on probiotic species, applications for specific strains, dosages and forms, safety, and shelf life is not sufficiently summarized to allow practical and consistent recommendations to be made by most food and nutrition professionals. In addition, prebiotic fibers-although providing nutraceutical and nutritional value-are a group of diverse carbohydrate ingredients that are poorly understood in regard to their origin, fermentation profiles, and dosages required for health effects. The science and practice-based guidelines presented here will enhance clinician and client understanding of probiotics and prebiotics, with the aim of improving appropriate recommendation and informed use of these emerging dietary ingredients and the products containing them.     

Management activities in community dietetics practice

Information on the management activities of community dietitians was obtained through a mail survey of 350 randomly selected community dietitians. Subjects provided information on their management level, the importance to their job performance of 83 management activity statements, and the percent of time they spent performing management activities in each of nine categories. Twenty-nine percent of the respondents indicated job responsibilities in lower-level management; 45% had mid-level and 26% had upper-level management responsibilities. Numbers of activities rated essential or very important increased as management levels increased. Kinds of activities changed from technical to human to conceptual as management levels increased. Mid-level management subjects, while still spending time working with clients, reported spending considerable time on coordinating, investigating, and evaluating, often reporting as much time spent on those activities as did upper-level management subjects. Definitions provided by respondents indicated great diversity in job requirements and settings.     

Nutrigenomics, individualism and public health

Issues arising in connection with genes and nutrition policy include both nutrigenomics and nutrigenetics. Nutrigenomics considers the relationship between specifc nutrients or diet and gene expression and, it is envisaged, will facilitate prevention of diet-related common diseases. Nutrigenetics is concerned with the effects of individual genetic variation (single nucleotide polymorphisms) on response to diet, and in the longer term may lead to personalised dietary recommendations. It is important also to consider the surrounding context of other issues such as novel and functional foods in so far as they are related to genetic modification. Ethical issues fall into a number of categories: (1) why nutrigenomics? Will it have important public health benefits? (2) questions about research, e.g. concerning the acquisition of information about individual genetic variation; (3) questions about who has access to this information, and its possible misuse; (4) the applications of this information in terms of public health policy, and the negotiation of the potential tension between the interests of the individual in relation to, for example, prevention of conditions such as obesity and allergy; (5) the appropriate ethical approach to the issues, e.g. the moral difference, if any, between therapy and enhancement in relation to individualised diets; whether the 'technological fix' is always appropriate, especially in the wider context of the purported lack of public confidence in science, which has special resonance in the sphere of nutrition.     

Specialty practice in dietetics: Empirical models and results

This article, which is the second of a two-part series, presents results for the second and third objectives of The American Dietetic Association (ADA) 1991 Dietetic Practice Study: to distinguish the task activities among registered dietitians practicing in renal nutrition, pediatric nutrition, and metabolic nutrition care; and to investigate the relationship between advanced-level practice and specialty practice. A nationwide mail survey of advanced-level practice was conducted on a stratified random sample of 8,012 beyond-entry-level (registered before April 1988) registered dietitians who were members of ADA and of dietetic practice groups (DPGs). The sample was supplemented with two randomly selected control groups of 1,000 entry-level and 1,000 beyond-entry-level registered dietitians. The operational definition for specialty practice was met by 1,925 sample members who were also included in the survey on practice in the three specialty areas. The overall response rate was 63.1%, and the total number of usable returns was 5,852. The results from a discriminant analysis of 121 specialty job tasks, administered in common to practitioners in each specialty, found that 84 tasks could be used to construct a generic model of specialty practice from which specific task lists were derived that defined practice in renal nutrition, pediatric nutrition, and metabolic nutrition care. Validation analyses found the generic model to be a reliable means of distinguishing the job activities in renal nutrition and in pediatric nutrition; it was somewhat less reliable for metabolic nutrition care. A weak relationship was found between advanced-level practice and practice in the three specialty areas. This was explained by the finding that many specialists do not meet the master's degree requirement of the model of advanced-level practice. Overall, the results from all analyses conducted suggest that it is reasonable to accept the picture of specialty practice constructed by this research as valid. The findings, therefore, establish the empirical basis for a specialty practice credential in the three specialty areas investigated.     

Nutrigenomics, obesity and public health

Functional genomics will change knowledge and practice in clinical nutrition in the forthcoming years. The possibility of performing an individual's genetic profile (genetic variations and epigenetic modifications) as well as the ability of its integration in a complex network of metabolic interactions represents a huge challenge in Human Nutrition. The influence of nutrigenomics in terms of prevention and treatment of chronic diseases, such as obesity, type 2 diabetes and cardiovascular disease in a population level remains undetermined for the moment. The opportunity of nutritional intervention in critical stages of development and the chance of changing genetic susceptibility to diseases through diet in a Public Health basis should lead the future of nutrigenomics beyond the mere design of "personalized" functional food or diets.     

Nutrigenomics, vitamin D and cancer prevention

Although there is growing epidemiological, preclinical and clinical evidence suggesting that low vitamin D intake, exposure and/or status is associated with an increased risk of various types of cancer, the optimum amount needed remains controversial. Furthermore, there is evidence that a U- or J-shaped response curve exist between 25(OH)D and certain cancers. Increasing information about the impact of genetic variation, especially polymorphisms that influence absorption, transport, metabolism and associated molecular targets, should help clarify inconsistencies in the data regarding vitamin D's effect on cancer risk. Rather than focusing on the main effects of a few variants of these genes alone, future studies need to consider gene-nutrient or environmental interactions. Nutrigenomics should clarify who might benefit and be placed at risk because of vitamin D exposure.     

American Dietetic Association: scope of dietetics practice framework

As a whole, the Framework provides a structure for our profession by describing the full range of resources available to us all, at every stage of development. At the broadest end of the spectrum, the Framework emphasizes the dietetics practitioner’s professional accountability and places decisions about boundaries of practice in the hands of the individual practitioner. It is intended to be used throughout the profession by students and educators, individual RDs and DTRs, people who have just entered the profession, people who have progressed to advanced or specialty practice, retired dietetics professionals who maintain the active RD or DTR credential, hiring managers, certification and licensure boards, national committee members, researchers, and anyone encountering new challenges at work. It serves as a tool for everyone who engages in the profession of dietetics. And, as we individually and collectively change to respond to new developments in the health care environment, so too will our Framework evolve over time to reflect this.     

Trying out the competency profile for entry-level nutrition/dietetics practice

The Ontario Regional Dietetic Internship Committee sponsored a workshop on "The Competency Based Profile", for Internship Directors and other dietitians involved with interns. The objectives of the workshop were: 1. to define the effects of implementation of some aspects of the competency profile into existing internship programs, 2. to exchange ideas regarding implementation, and 3. to give Internship Directors a further insight into the pros and cons of competency based education. Nine internship programs implemented some aspects of the profile. From one to seven dietetic interns and one to eleven dietitians were involved per program. Their findings were that the profile took on the average more time to complete than the regular CDA Dietetic Interns' Evaluation Forms. The profile could not be used as the sole evaluation tool. It was however an effective diagnostic tool. The rating scale is not well worded nor is its numerical system an effective way to evaluate dietetic interns. The competency profile is not suitable for all types of internship programs. Specialized internships have to expand on the profile to meet their own needs.