Integrating the Totality of Food and Nutrition Evidence for Public Health Decision Making and Communication

The interpretation and integration of epidemiological studies detecting weak associations (RR < 2) with data from other study designs (e.g., animal models and human intervention trials) is both challenging and vital for making science-based dietary recommendations in the nutrition and food safety communities. The 2008 ILSI North America “Decision-Making for Recommendations and Communication Based on Totality of Food-Related Research” workshop provided an overview of epidemiological methods, and case-study examples of how weak associations have been incorporated into decision making for nutritional recommendations. Based on the workshop presentations and dialogue among the participants, three clear strategies were provided for the use of weak associations in informing nutritional recommendations for optimal health. First, enable more effective integration of data from all sources through the use of genetic and nutritional biomarkers; second, minimize the risk of bias and confounding through the adoption of rigorous quality-control standards, greater emphasis on the replication of study results, and better integration of results from independent studies, perhaps using adaptive study designs and Bayesian meta-analysis methods; and third, emphasize more effective and truthful communication to the public about the evolving understanding of the often complex relationship between nutrition, lifestyle, and optimal health

Considerations for best practices in studies of fiber or other dietary components and the intestinal microbiome

Considerations for best practices in studies of fiber or other dietary components and the intestinal microbiome. Am J Physiol Endocrinol Metab 315: E1087–E1097, 2018. First published August 21, 2018; doi:10.1152/ajpendo.00058.2018.—A 2-day workshop organized by the National Institutes of Health and U.S. Department of Agriculture included 16 presentations focused on the role of diet in alterations of the gastrointestinal microbiome, primarily that of the colon. Although thousands of research projects have been funded by U.S. federal agencies to study the intestinal microbiome of humans and a variety of animal models, only a minority addresses dietary effects, and a small subset is described in sufficient detail to allow reproduction of a study. Whereas there are standards being developed for many aspects of microbiome studies, such as sample collection, nucleic acid extraction, data handling, etc., none has been proposed for the dietary component; thus this workshop focused on the latter specific point. It is important to foster rigor in design and reproducibility of published studies to maintain high quality and enable designs that can be compared in systematic reviews. Speakers addressed the influence of the structure of the fermentable carbohydrate on the microbiota and the variables to consider in design of studies using animals, in vitro models, and human subjects. For all types of studies, strengths and weaknesses of various designs were highlighted, and for human studies, comparisons between controlled feeding and observational designs were discussed. Because of the lack of published, best-diet formulations for specific research questions, the main recommendation is to describe dietary ingredients and treatments in as much detail as possible to allow reproduction by other scientists

Perspective:Dietary Biomarkers of Intake and Exposure - Exploration with Omics Approaches

While conventional nutrition research has yielded biomarkers such as doubly labeled water for energy metabolism and 24-h urinary nitrogen for protein intake, a critical need exists for additional, equally robust biomarkers that allow for objective assessment of specific food intake and dietary exposure. Recent advances in high-throughput MS combined with improved metabolomics techniques and bioinformatic tools provide new opportunities for dietary biomarker development. In September 2018, the NIH organized a 2-d workshop to engage nutrition and omics researchers and explore the potential of multiomics approaches in nutritional biomarker research. The current Perspective summarizes key gaps and challenges identified, as well as the recommendations from the workshop that could serve as a guide for scientists interested in dietary biomarkers research. Topics addressed included study designs for biomarker development, analytical and bioinformatic considerations, and integration of dietary biomarkers with other omics techniques. Several clear needs were identified, including larger controlled feeding studies, testing a variety of foods and dietary patterns across diverse populations, improved reporting standards to support study replication, more chemical standards covering a broader range of food constituents and human metabolites, standardized approaches for biomarker validation, comprehensive and accessible food composition databases, a common ontology for dietary biomarker literature, and methodologic work on statistical procedures for intake biomarker discovery. Multidisciplinary research teams with appropriate expertise are critical to moving forward the field of dietary biomarkers and producing robust, reproducible biomarkers that can be used in public health and clinical research

Twentieth-century trends in essential fatty acid intakes and the predicted omega-3 index: evidence versus estimates

Although the health benefits of omega-3 (n–3) fatty acids are widely appreciated, those of the omega-6 (n–6) fatty acids have become somewhat controversial in recent years, with some viewing them as harmful at current intakes (1, 2) and others (3) [including the American Heart Association (4)] supporting the status quo. Understanding the relations between intakes of these essential fatty acids and disease prevalence over time could inform the debate. To that end, this issue of the Journal contains a report by Blasbalg et al (5) that attempts to reconstruct those intakes and, from this information, to estimate fatty acid tissue content (eg, the Omega-3 Index [red blood cell eicosapentaenoic plus docosahexaenoic acid (EPA+DHA) (6)]). Low concentrations of the latter have been linked to increased risk of total mortality (7), cellular aging (8), depression (9), and acute coronary syndromes (10). In reconstructing historical intakes, Blasbalg et al (5) used United States Department of Agriculture (USDA) commodity disappearance data and made multiple assumptions and estimations regarding, for example, the completeness of USDA food and nutrient databases, the extent of wastage, the considerable differences in the amount and types of foods shipped in from outside of the United States (which would be particularly true for seafood), the proportions consumed by people (as opposed to animals or used for industrial purposes), and so forth. The USDA/Center for Nutrition Policy and Promotion approach used by these authors assumes that the fatty acid content of various foods did not change over the second half of the 20th century. In fact, many meat products, fats and oils (which were subjected to varying degrees of hydrogenation), and processed foods containing everchanging blends of commodity oils entered the food supply during this time. Consequently, Blasbalg et al’s reported intakes of both short-chain [α-linolenic acid (ALA) and linoleic acid (LA)] and long-chain, highly unsaturated fatty acids (HUFAs) of the n-6 and n-3 series cannot easily be independently verified and must remain as rough estimates only

Clinical research strategies for fructose metabolism.

Fructose and simple sugars are a substantial part of the western diet, and their influence on human health remains controversial. Clinical studies in fructose nutrition have proven very difficult to conduct and interpret. NIH and USDA sponsored a workshop on 13-14 November 2012, "Research Strategies for Fructose Metabolism," to identify important scientific questions and parameters to be considered while designing clinical studies. Research is needed to ascertain whether there is an obesogenic role for fructose-containing sugars via effects on eating behavior and energy balance and whether there is a dose threshold beyond which these sugars promote progression toward diabetes and liver and cardiovascular disease, especially in susceptible populations. Studies tend to fall into 2 categories, and design criteria for each are described. Mechanistic studies are meant to validate observations made in animals or to elucidate the pathways of fructose metabolism in humans. These highly controlled studies often compare the pure monosaccharides glucose and fructose. Other studies are focused on clinically significant disease outcomes or health behaviors attributable to amounts of fructose-containing sugars typically found in the American diet. These are designed to test hypotheses generated from short-term mechanistic or epidemiologic studies and provide data for health policy. Discussion brought out the opinion that, although many mechanistic questions concerning the metabolism of monosaccharide sugars in humans remain to be addressed experimentally in small highly controlled studies, health outcomes research meant to inform health policy should use large, long-term studies using combinations of sugars found in the typical American diet rather than pure fructose or glucose