Sample Collection, Preservation, and Data Analysis in Gut Microbiome Research: Current Methods and Potential Impact on Results

The development of dietary guidance relies upon the ability to synthesize a body of evidence and arrive at a reasonably well-supported conclusion. Although publications have purported to identify characteristics of a “healthy gut microbiome”, the one certainty at present is that gut microbiome is highly variable across individuals. In addition, the reality is that gut microbiome research still requires method advancement and refinement. Continuing to improve methods, and working toward alignment across laboratories will move all closer to understanding how diet can impact health at the point of the gut microbiome. In a virtual workshop held on October 13, 2022, the current state of knowledge related to sample collection, utility of standards, sequencing, and bioinformatic and biostatistical approaches was reviewed by experts working in the field. Speakers expanded on how selection among the various methodological options can impact study results. This project includes generating a summary of these discussions will be prepared for submission to a peer-reviewed journal.

Scientific Editor: Riley Hughes, PhD, Independent Scientist

Amount: $3,000

Year: 2022

This work was supported by the IAFNS Gut Microbiome.

Understanding the Opportunities and Challenges to Sodium Reduction in Food Service and Key Strategies to Foster Progress

The objective of this project is to document the outcomes of a dialogue with leaders from the food service sector, government, and academia to understand the challenges and opportunities related to sodium reduction in the food service sector. This work related to the dynamics, initiatives, and challenges in the food service sector will help identify and communicate opportunities to foster progress with sodium reduction, inform public health initiatives around sodium and to track progress over time.

Scientific Editor: Paula Trumbo PhD, Liberty University, Lynchburg VA

Amount: $6500

Year: 2022

This work was supported by the IAFNS Sodium Committee.

Quality of Popular Diet Patterns in the United States: Evaluating the Effect of Substitutions for Foods High in Added Sugar, Sodium, Saturated Fat and Refined Grains

Reconciliation of Differences between Observational Studies and Randomized Controlled Trials: A Case Study on Low Calorie Sweeteners

Scientific evidence is commonly categorized into levels based on quality of evidence, commonly referred to as the hierarchy of evidence. The complexity of evaluating study quality based on study design becomes problematic for dietary exposures and health outcomes with conflicting evidence observed in observational studies and RCTs. Such conflicting evidence is well documented for low calorie sweeteners (LCS), in which observational trials tend to identify adverse associations between LCS use and adiposity, type 2 diabetes (T2D), mortality, cardiovascular disease (CVD), and cancer while RCTs highlight benefits or no effect of LCS on body weight, energy intake, markers of T2D, and markers of CVD (6). One possible explanation for this is that observational trials and RCT are simply addressing different research questions, evaluating different exposures, comparators, and outcomes.


The objective of the proposed project is to educate stakeholders on how to interpret contrasting evidence from observational studies and RCTs based on methodological differences between study designs, using LCS as a case-study. A rapid review of systematic reviews and metaanalyses on LCS and various health outcomes will be conducted to highlight how different intervention/exposures, comparators, outcomes, and study designs produce varying conclusions regarding the efficacy and safety of LCS. The deliverables of this project will be a peer-reviewed publication and presentation of findings at a conference for nutrition and dietetics practitioners

Institution: USDA Agricultural Research Service

Principal Investigator: Kelly Higgins, MPH PhD; David Baer, PhD

Amount: $2K (Matthew Kramer, USDA ARS - retired); other costs covered by USDA’s congressional appropriation

Year: 2022

This work was supported by the IAFNS Low- and No-Calorie Sweeteners Committee.

Development of a Human Whole-Stool Reference Material – NIST Collaboration

Over the past 10+ years, it has become evident that the human gut microbiome plays a critical role in a vast and disparate set of health and disease states; including diabetes, obesity, cancer and depression. To identify new biomarkers that may serve as disease indicators and to understand biologically‐relevant properties of the human gut microbiome, validated measurements that accurately describe various properties of the microbial community, both quantitatively and qualitatively, are needed. The aim of this project is to develop a set of Human Whole Stool Reference Materials that are certified by the National Institute for Standards and Technology (NIST) for clinically-relevant metabolites. The set will be derived from a small cohort of donors who are selected based on their health or disease state (e.g. obesity vs. healthy, diet controlled, etc.). IAFNS is collaborating with NIST to develop a list of metabolites with likely relevance for health, that would be useful to include/measure in the material.

Institutions: The National Institute for Standards and Technology, BioIVT

Principal Investigator: The National Institute for Standards and Technology

Amount: $73,450

Year: 2022

Read more: Workshop Report: Toward The Development Of A Human Whole Stool Reference Material For Metabolomic And Metagenomic Gut Microbiome Measurements

This work was supported by the IAFNS Gut Microbiome Committee.

Protein Quality Measurement Approach in North America

Protein quality has not been an issue in North America populations in the recent past due to the quantity and quality of protein consumed. However, as food sources shift, quality of protein may become a more important consumer decision factor in their individual choice of foods. This proposed in vitro protein digestibility method will provide an alternative to replace animal testing as an immediate, scientifically, and ethically sound approach to encourage more food manufacturers to measure and maintain protein quality in foods being developed with plant and alternative protein sources in North America.


Institution: University of Manitoba

Principal Investigator: Dr. James House

Amount: $130,000

Year: 2022

This work was supported by the IAFNS Protein Committee.

Comparison of Food Category Contributors to Sodium Intake from Stores vs. Restaurants

The FDA released the final voluntary sodium reduction guidance in 2021. The targets presented are applicable to both consumer packaged goods and prepared/restaurant foods. Research indicates that the sodium contribution of restaurant foods is greater than that of foods consumed at home, including processed foods. There is an opportunity to understand these contributions, in totality and at the food category level, using updated data – to better target sodium reduction efforts. Distinguishing the contribution of foods from at home (including processed foods from a grocery store) compared to away-from-home consumption is important, as emphasis on e.g., the restaurant sector may have the greatest impact on intake. In addition, understanding the specific food category contributors from each source may indicate that emphasis on specific foods differs for foods consumed at home compared to away-from-home. This could inform food development, recipe formulation, and dietary guidance. The SoFHI committee is supporting an analysis of NHANES 2017-2018 to test the hypothesis that the types of foods obtained from restaurants are associated with higher levels of sodium intake compared to the types of foods obtained from stores.

Institution: Food & Nutrition Database Research, Inc.
Principal Investigator: Debra R. Keast, PhD
Amount: $47,500
Year Awarded: 2022

This work is supported by IAFNS Sodium Committee.

View this project on the Center for Open Science's Open Science Framework.