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Investigation of the Relationship Between Live Dietary Microbe Intake and Health Outcomes, Using the Korean National Health and Nutrition Examination Survey (KNHANES)

Research has shown that the consumption of live microbes, including and beyond probiotics, is associated with health benefits. Fermented foods, such as yogurt and kimchi, are rich in live bacteria and may help to promote a healthy gut microbiome and support overall health. Consuming fermented foods may be associated with a range of health benefits, […]

Understanding and Advancing Best Practices for Human Nutrition & Gut Microbiome Research


In 2017, the National Institutes of Health (NIH) collaborated with the US Department of Agriculture, Agricultural Research Service (USDA-ARS) to develop and document “Considerations for Best Practices in Studies of Fiber or Other Dietary Components and the Intestinal Microbiome” (Klurfeld et al. 2018). The primary recommendation resulting from this exchange was to “describe dietary ingredients and treatments in as much detail as possible to allow reproduction by other scientists.”

Since 2017, science around diet-gut microbiome-health relationships has continued to proliferate. While there have been several publications addressing methods for human research on diet-gut microbiome-and health, the extent to which “best practices” have been articulated in this field is not known. In addition, there are many publications focused on best practices in human nutrition research generally, but the degree to which these are applicable to gut microbiome studies versus needing additional or different guidance has not been explored.

This project aims to improve the conduct of, and alignment across, gut microbiome research. Capturing the latest knowledge regarding best practices and “suggested” practices based on researcher experience and encouraging implementation would support the harmonization of research and improve the ability to compare studies and conduct meta-analyses to address key questions. This project starts with an umbrella review of published guidance to identify gaps. These gaps will then be addressed by an appropriate mechanism to understand and convey the state of knowledge on optimal research designs and methods in this field.

Expert Group:

Chris Cifelli, PhD, National Dairy Council
Cindy Davis, PhD, USDA-ARS
Tatiana Diacova, MS RD, UC Davis
Hannah Holscher, PhD RD, University of Illinois at Urbana-Champaign
Mary Kable, PhD, UC Davis and USDA-ARS
Philip Karl, PhD, RD, USARIEM
Johanna Lampe, PhD RD, Fred Hutch Cancer Center
Kelly Swanson, PhD, University of Illinois at Urbana-Champaign

Year: 2023

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

This work is supported by the IAFNS Gut Microbiome Committee.

Understanding Adolescence as a Critical Period for Immediate and Long-term Cognitive Health Impact – Systematic Review

It is well-established that the prenatal period and infancy (the first 1000 days) are critical for cognitive development, and nutrition during these periods can impact cognitive performance later in life. Specific nutrients are therefore emphasized during pregnancy and infancy, to include choline, iron, folate and iodine, with emerging evidence for a role of many other nutrients and food components. Less attention has been paid to the effects of nutrition in early childhood through adolescence. It is notable that a systematic review was published in January 2022 examining the effects of nutritional interventions on cognitive development in children ages 1 through 6 years (Roberts et al. 2022). Positive effects were identified for supplementation with iron and other nutrients, as well as for fish intake.

The IAFNS committee was not able to identify this type of review for adolescence, either examining effects of nutrients consumed during adolescence on cognitive performance at that age, or later in life. In fact, a recent series on nutrition in adolescence published in the Lancet (see Patton et al. 2022) notes that adolescence has been overlook as a critical growth period, citing the examples of a complete lack of adolescent-specific targets in the Sustainable Development Goals for nutrition. Other than two systematic reviews on related, but peripheral topics, there do not appear to be other reviews, systematic or otherwise, on the topic of the role of nutrient intake broadly in cognitive development and performance during adolescence – or effects of nutrients in adolescence on cognition later in life, indicating a need to document what is known as well as knowledge gaps to support and motivate more work in this area.

Institution: Swansea University

Principal Investigator: Hayley Young, PhD

Year: 2023

This work was supported by the IAFNS Cognitive Health Committee.

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

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

Year: 2022

This work was supported by the IAFNS Protein Committee.

Guiding Principles for Funding Food Science and Nutrition Research

With the limited availability of funds from federal agencies, nongovernmental sources of funding - including industry - play a critical role in offering new opportunities for advancement and innovation in food and nutrition research. While bias can present itself in a multitude of ways, with no person, entity, or sector free from its grasp, these updated Guiding Principles serve as a tool that funding organizations can use to protect the integrity and credibility of the scientific record from the potential influence related to funding source.

The updates to these Guiding Principles strengthen guardrails that separate the funding from the science, reflect the shift in the scientific community towards open science, and provide greater transparency on interactions between the funder and investigator.

Read the full publication.

Watch a 5-min video of the updated Guiding Principles.

This work was supported by the IAFNS Assembly on Scientific Integrity.

Heavy Metals in US Foods: Exposure Assessment by Age Group and Mitigation Strategies

Heavy metals such as arsenic (As), cadmium (Cd), lead (Pb), and mercury (Hg) have the potential to cause neurocognitive impairment to infants and young children who are exposed to them in their diets. These elements can also cause chronic toxicological effects in older children and adults. To help address these risks it is important to identify which foods contain the highest levels of these metals; and based on US consumption of these foods by age group, which food-metal combinations cause the greatest potential exposure via diets. This research will examine which foods contain the highest levels of heavy metals; and based on US consumption of these foods by different age groups, which food-metal dyads cause the greatest human exposures. The researchers will then explore mitigation strategies to reduce these most severe exposures. Feasibility and cost-effectiveness of the strategies must be assessed to provide a realistic picture of what we can achieve in the short term to quickly lower exposures.

Institution: Michigan State University

Principal Investigator: Felicia Wu, PhD.

Date Awarded: May 5, 2022

Read more: Dietary Exposure to Cadmium from Six Common Foods in the United States.

This project is supported by the IAFNS Food and Chemical Safety Committee.


A Framework for Heavy Metal Prioritization and Mitigation for Reducing Metal Intake: Rice and Spinach Case Studies

Rice is a significant source of arsenic and other elemental toxins (e.g. mercury and cadmium) to the human diet, particularly in foods for babies and young children. Spinach is a significant source of the highly toxic metals Cd and Pb as well as other chemicals with negative health implications (e.g., organics, perchlorate), but the processes that lead to levels of concern in spinach differ from those in rice. This project will aim to design an adaptive, multi-part scoring system as the basis for prioritization of mitigation factors. This system will account for differences in commodities, metal combinations, soil-plant interactions and geochemistry, processing methods, and impact of these terms on the mean and variability of the metal concentrations of interest. This method should assess approaches to mitigation, helping prioritize methods that are both effective and achievable. In both risk and mitigation assessments, results will highlight research gaps, new research and action priorities, and propose a ranked and detailed set of proposed solutions.

Institution: University of Arkansas

Principal Investigator: Benjamin Runkle, PhD

Date Awarded: April 13, 2022

This research is supported by the IAFNS Food and Chemical Safety Committee.

The Scientific Basis of Communicating Carbohydrate Quality

A workshop was convened jointly with Diabetes Canada to advance the dialogue between scientists and regulatory experts on science-based indices that can be used in communicating physiologic effects of carbohydrates in foods. Experts agreed that the carbohydrate quality of a food would take into account multiple factors, including whole food credentials, the glycemic response to […]

Standing Committee on Bioactive Recommendations

Growing evidence suggests that lutein for vision and flavan-3-ols for cardiovascular disease could be candidates for quantified recommended intakes. In 2014, Elwood et al. pointed out the challenges and suggested that a framework be developed to recommend bioactive intakes not currently covered by approaches used to establish nutrient intakes to prevent deficiencies. A standing committee […]

Beverage Caffeine Intake Study

A large variety of new caffeinated beverage products have entered the market in recent years, including new types of energy drinks, cold brew and ready-to-drink specialty coffees and teas, and caffeinated waters and sports drinks. With shifts towards remote work and learning, online food and grocery ordering, and rapid pickup and delivery options for consumers, an updated evaluation of beverage consumption patterns and caffeine intakes in the U.S. population is warranted. The study will provide a current perspective on caffeinated beverage consumption patterns and caffeine intakes from a nationally representative sample of the U.S. population.

Institutions: Penn State, Kantar
Principal Investigator: Diane Mitchell, MS, RD, Penn State
Year Awarded: 2021

This work was supported by the IAFNS Caffeine Committee.