Workshop summary: building an NHANES for the future

Abstract

The American Society for Nutrition’s (ASN) Committee on Advocacy and Science Policy (CASP) organized a workshop, “Building a National Health and Nutrition Examination Survey (NHANES) for the Future,” held during NUTRITION 2023, which took place in Boston, MA in July 2023. CASP had already identified an urgent need for increased support and modernization to ensure that a secure future for NHANES is achievable. The survey faces challenges associated with data collection, stagnant funding, and a need for more granular data for subpopulations and groups at risk. The workshop provided an overview of NHANES, including the nutrition component, and the many other uses for the survey’s data, which extend beyond nutrition. Speakers highlighted NHANES’s current and emerging challenges, as well as possible solutions to address these challenges, especially with regard to response rates of underrepresented groups, linkage of survey data to other resources, incorporation of new survey methodologies, and emerging data needs. The workshop also included a “Town Hall” component to gather additional feedback on NHANES’ challenges and proposed solutions from audience members. The workshop provided many possible action items that ASN will explore and use to inform effective continued advocacy in support of NHANES and to find possible opportunities for ASN and others to partner with the Centers for Disease Control and Prevention National Center for Health Statistics to strengthen this vital survey and maintain its robust and relevant data moving forward.

Introduction

For >50 y, NHANES has served as an unparalleled data resource that has benefited nutrition science and public health in numerous ways. The survey’s overarching goal is to assess the health and nutritional status of adults and children in the United States through a combination of interviews, physical examinations, and laboratory tests. NHANES is designed as a nationally representative sample of the United States civilian, noninstitutionalized population, and currently releases data in 2-y cycles. Selected subpopulations are oversampled during different cycles to allow estimates for certain subgroups (e.g., Blacks/African Americans, Hispanics, Asian Americans, pregnant females, children, and adolescents).

NHANES data are essential to monitor the health and nutrition of our nation, but it is threatened by challenges, such as decreasing survey response rates and increasing research costs. For example, there have typically been ∼10,000 participants in each data collection cycle, but response rates fell to their lowest yet, 46.9%, for NHANES cycle 2017–March 2020 (pre-pandemic), continuing a trend of declining response rates [1]. The survey has numerous federal partners and other collaborators; ∼30%–40% of its $40 million annual budget is provided by collaborators. However, there are increasing research costs to implement NHANES. As we look ahead, there is a critical need to find new ways to ensure NHANES’ sustainability and impact, given the ever-growing need for more health and nutrition data, balanced with the challenges the survey faces.

As part of American Society for Nutrition’s (ASN) continuing efforts to support and strengthen NHANES, an interactive workshop was held during NUTRITION 2023 to discuss the future of the survey, including opportunities to evolve its nutrition core and strategies for modernization. The workshop was organized by ASN’s Committee on Advocacy and Science Policy (CASP) and moderated by CASP member, Alison Brown, PhD, RDN, Program Director at the National Institutes of Health, National Heart, Lung, and Blood Institute and Chair of the ASN Foundation, Catherine Woteki, PhD, Professor of Food Science and Human Nutrition at Iowa State University. The workshop was organized following several previous CASP-organized activities that also explore strengthening NHANES, including:

• •A September 2022 webinar “NHANES: Opportunities for Revitalization” and an associated blog post summary [2];
• •A February 2023 Information Brief “Building an NHANES for the Future” that is used in the society’s advocacy efforts [3]; and
• •A May 2023 American Journal of Clinical Nutrition article “Critical data at the crossroads: the NHANES faces growing challenges” [4].

The previous article complements this workshop summary; it provides an in-depth examination of the specific challenges affecting the survey (Table 1), thereby providing the context for holding this forward-looking workshop exploring future opportunities to strengthen and support NHANES.

TABLE 1.

Challenges identified in “Critical data at the crossroads: the National Health and Nutrition Examination Survey faces growing challenges [4]”

•Rising costs of conducting research and stagnant funding

•Response rates for virtually all federal surveys including NHANES have declined dramatically, requiring innovative ways to assure representative data

•Nutrition-related interests are changing (e.g., nutrients of concern)

•Addressing the challenge of health disparities requires increased diversity of the study population in NHANES that will be difficult to achieve given the cost of data collection

•Modernization and “re-imagination” of the United States public health data infrastructure is an emerging national priority

•NHANES must meet emerging needs within real-world constraints while taking on newer methodologies and potentially altered approaches for both how and what data are collected

NHANES Overview

The Division of Health and Nutrition Examination Surveys (DHANES) at the National Center for Health Statistics (NCHS) within Centers for Disease Control and Prevention is responsible for the survey’s planning and operations as well as informatics and data analysis. The workshop began with an overview of NHANES, including a closer look at the survey’s nutrition component, provided by members of the DHANES team; Cynthia L. Ogden, PhD, DHANES Analysis Branch Chief and Naman Ahluwalia, PhD, NHANES Nutrition Monitoring Advisor, respectively.

NHANES covers all aspects of nutrition, including biological markers, nutrition knowledge and behaviors, dietary intake of food and beverages, as well as dietary supplement use, and anthropometry; its questionnaire, examination, and laboratory components are summarized in the Survey Content Brochure [5]. Because participants are seen in person, very precise assessment methods, such as dual x-ray absorptiometry for determining bone density, are used. Stored DNA samples and genetic data have been collected from various NHANES cycles as well, which add to the robustness of the information found in the datasets, although many uses with genetic data are restricted [6]. These data will become increasingly useful because precision nutrition efforts continue to be pursued in the future. The unique NHANES resource presents the opportunity for expanded complex analyses to contribute to precision nutrition, particularly with the use of genomics, metabolomics, and microbiome analyses. Challenges such as sample collection and costs of analyses will be present; however, it is expected that the payoff in scientific knowledge is so valuable that contributors would value these inputs.

What We Eat in America—the dietary intake component of NHANES—is performed in partnership with the USDA. Historically it has included two 24-h dietary recalls administered by trained interviewers, who are bilingual in Spanish and English. Although the first recall was traditionally conducted in person, whereas the second was done over the phone, several years ago this was changed to both being done over the phone to minimize contact time during the COVID-19 pandemic, and this is still being performed in this way. In addition to dietary recalls, questionnaires are used to collect data on topics including infant feeding practices, weight history, food insecurity, nutrition knowledge, and familiarity with federal nutrition education tools such as MyPlate.

The data captured from NHANES are published in peer-reviewed journals; in addition, DHANES staff author publications such as NCHS data briefs on specific topics and NCHS methodological reports, and publish key articles in Centers for Disease Control and Prevention’s Morbidity and Mortality Weekly Reports. To help users, the NHANES website provides survey data and documentation, an analysis tutorial, and information on how to access the Research Data Center, where users can access other sources of nonpublic data that are linked with NHANES data, such as the National Death Index, and data from Medicare and Medicaid and the Department of Veterans Affairs [7].

NHANES data are widely used in clinical settings and to inform nutrition research and policy (Figure 1). The pediatric growth charts are a widely known example in which anthropometric data collected from NHANES have been incorporated into the development of this reference standard [8]. NHANES data on nutritional biomarkers were instrumental in setting fortification policies that helped to greatly reduce risks of iron, iodide, and folic acid deficiencies in the United States. NHANES nutrition data can be linked with a wide range of other sociodemographic variables, environmental exposures, and health outcome data points also collected in the survey. NHANES data can also be linked to the National Death Index, allowing passive longitudinal follow-up of survey participants and examination of associations between nutritional intake, status, and behaviors and the outcomes of total and cause-specific mortality. Thus, NHANES data have become a critical resource for nutrition epidemiology research that examines associations between nutrition and health or wellbeing as well as for informing several national nutrition and health policies.

FIGURE 1.

NHANES comprehensive data provide basis for informing United States nutrition policy.

Changes for the 2025–2026 Cycle

Alan E. Simon, MD, DHANES Director, provided a look at what is ahead for NHANES. Data collection teams should be back in the field in January 2025 and, although the next cycle of NHANES will remain much the same in terms of its overall approach, there is a lot of work being done to make data collection more efficient and to boost response rates.

One important change is that the mobile health units will now be housed in smaller trucks instead of large trailers (Figure 2). Instead of 3 sets of trailers, there will be 5 sets of 3 trucks—2 for examinations, 1 for the laboratory—traveling around the country at a time. The switch to trucks will allow the units to move around more easily and to set up in >1 location in a county, allowing them to be closer to where participants live. This improved accessibility is intended to increase response rates. Using 5 sets of mobile units instead of 3 will also allow NHANES to reach participants from 20 counties a year instead of 15. Although this will not be used to increase the total number of participants, including households from a larger array of counties is expected to increase the survey’s statistical power and make it possible to create estimates for smaller population subgroups than was possible previously.

FIGURE 2.

NHANES to utilize trucks compared with trailers.

DHANES is also looking at various incentives to help increase the response rate. Monetary incentives are being considered, as are improved ways to provide participants with the results of their medical tests. To streamline processes, there are efforts to develop a participant portal that will allow results to be returned to participants more effectively.

Other efforts are focused on boosting the speed and efficiency of the information technology architecture that gets the data from survey participants to the public use files, which can be accessed by researchers. DHANES is also working with USDA on potential improvements that would allow the dietary data to be ready for public release faster, while maintaining quality. Currently, public use data releases occur on a biannual basis. Initial data releases take place ∼9 mo after the completion of a 2-y data collection cycle, with intermittent releases to follow until all remaining data have been processed for public use [9].

Highlights from Panel Discussion on Challenges and Opportunities to Optimize NHANES

The NHANES update was followed by insights from a panel of ASN members who use data from the survey. The topics for each panelist to address were selected by ASN’s CASP, based on the Committee’s earlier work determining areas in need of revitalization, including improving response rates, reaching underrepresented groups, facilitating data linkages, incorporating new survey methodologies, and addressing emerging data needs. Panelists were assigned specific questions to address before the workshop that provide more insight into the challenges that NHANES faces. Those questions are numbered below. All panelists touched on how NCHS could better identify and engage new potential collaborators with NHANES.

• 1.NHANES, like many surveys, has faced challenges because of declining response rates, a major problem potentially impacting the external validity (or generalizability) of any research leveraging NHANES. NHANES is particularly challenged because survey protocol involves considerable commitment, including a physical examination. What do you see as options for increasing and sustaining survey participant response rates?

Panelist Shilpa Bhupathiraju, PhD, Assistant Professor at Harvard Medical School and Brigham and Women’s Hospital, agreed that switching to smaller, more mobile trucks that can be closer to where people live was a good way to help improve response rates. She also emphasized that community engagement, although it takes time, can be an important strategy. She suggested that taking a personalized approach for the introductory letter—framing NHANES as either a general health survey or a chronic disease survey, for example—might help make participating more attractive to certain groups. She also highlighted opportunities to reduce the burden of participation in the study, such as by using apps, wearables, and other tools to enable remote data collection.

• 2.DHANES can address the need for data for certain subpopulations by oversampling within the national survey or by doing special studies (as has been done in the past if there is public health interest and funding). Given resource constraints on the size of the national probability sample, DHANES would have to make some adjustments to ensure that the types of granular data needed for public health policy decision making are included in the survey (such as the need to ensure data for minority populations and vulnerable groups). For the nutrition community, which subpopulation groups are highest priority and why? Could the current survey design produce reliable estimates for these groups? If not, what approaches and focus would be needed for NHANES to provide the high-priority data?

Panelist Katherine L. Tucker, PhD, Professor of Biomedical and Nutritional Sciences and Director of the Center for Population Health at the University of Massachusetts Lowell, presented ideas for obtaining the granular information that is important for the nutrition community while keeping in mind current resource restraints (Figure 3). She expressed concern that some groups are oversampled to gain insights into minority populations, but other minority groups are not, leading to data gaps. For example, for Hispanic populations, Mexican Americans are oversampled but Puerto Ricans, who have very different diets and risk factors compared with Mexican Americans, are not. The same is true for the Asian population, where South Asians are not distinguished from East Asians. Although she acknowledged that it is not feasible to oversample every minority group all the time, she suggested that the survey could rotate through these groups in various cycles to provide useful granular data even if data collections for these groups are more spread out temporally. She also said that there is a need for more data from pregnant and lactating participants, as well as greater representation from older groups, because the overall population is aging.

• 3.Are there federal administrative datasets, calculated indices, or other databases that would be useful to have linked to NHANES data that are not already linked?

FIGURE 3.

Improving granularity and diversity of NHANES population data.

Panelist Victor Fulgoni III, PhD, Senior Vice President of Nutrition Impact, LLC, discussed ways to improve access to, and the utility of, NHANES data. He said that researchers would find it helpful to have more timely dietary intake data and, in particular, usual intake data per cycle and per 4–6 y of data for certain subgroup analyses. He also suggested linking the Healthy Eating Index totals and subscores with participants, rather than relying on users to perform this coding themselves. He further suggested the use of nutrient density metrics and delineation of foods, such as minimally and ultraprocessed foods, noting that it may be worth examining opportunities to link survey data with additional data sources, such as grocery receipts or other food sales data, school test scores, and environmental impact databases. Considering the recent sharp increase in food prices, he also emphasized that food costs need to be updated with each NHANES cycle.

• 4.Many of the nutrition-related measures in NHANES were established long ago. What are the emerging nutrition-related data needs that now require a focused effort (e.g., inclusion of novel nutrient biomarkers, data on cultural foods, etc.)?

Panelist Colin Rehm, PhD, Senior Principal Scientist with PepsiCo, said that the potential linkages possible with NHANES are very powerful, but often underutilized, largely because of administrative hurdles involved in identifying and navigating the necessary data centers. Regarding potential new measures that could be included in the survey, he cautioned NHANES leaders not to pursue all the latest and greatest biomarkers but to, instead, take the time to examine how biomarkers can be used to improve data quality, for example, by helping to correct errors in self-reported data. Noting that 1000-person subsamples can be useful and cost-effective, he suggested that this approach might be useful for testing new biomarkers, as was previously done for sodium, an important public health priority area where self-reported data are insufficient to fully inform interventions and policy. The detailed data for NHANES participants, along with the ability to link with the National Death Index, could support the addition of complex biomarkers and increasing use of omics, including blood samples for genomics, proteomics, metabolomics, and stool samples for microbiome analysis in the future. In addition, new artificial intelligence approaches may be able to mine these data to great success.

• 5.What are the interests, concerns, and considerations related to use of newer technologies to gather information on food and nutrient intake (such as use of virtual 24-h recall and wearable physical activity monitors)?

Panelist Heather Eicher-Miller, PhD, Professor of Nutrition Science at Purdue University, provided additional insights into new technologies that could be useful (Figure 4). She pointed to remote web-based data collection tools such as the National Cancer Institute’s Automated Self-Administered 24-H (ASA24) Dietary Assessment Tool. The ASA24 is self-completed and not reliant on scheduling a phone interview that could improve response rates for the survey’s dietary component. Although web-based tools could present a barrier for people with disabilities or those who are not comfortable with technology, combining them with in-person or phone-based interviews might overcome these drawbacks. Image-based methods are another possibility for dietary recall. Although there are many iterations, these approaches generally involve taking pictures of foods before and after they are consumed. These images can be used for automated identification of the food and portion size, although this usually requires an analyst, or the respondent helps with this task. Image-based methods could help reduce the burden on the respondent and provide more accurate portion size information, but significant development work would need to take place to adapt these for NHANES, because there are no off-the-shelf methods available currently.

FIGURE 4.

New technologies to capture food and nutrient intake.

Advancing Nutrition Research using NHANES

The workshop also included a Town Hall session during which attendees provided ideas for what NHANES can do in the future and ways that ASN could help. To elevate the visibility of NHANES among decision makers, one suggestion was for ASN to develop talking points conveying the important role of NHANES in supporting United States public health in general, and nutrition in particular. ASN or another group could also convene regular meetings among researchers who frequently use NHANES data to foster a community of practice that could provide guidance, make connections, and potentially identify funding or other resources. Participants also suggested that ASN could help to inform survey improvements by coordinating input for updating methods for the core nutrition and diet measurements performed in NHANES.

To address data gaps, participants suggested looking more closely at how to engage state partners, perhaps with technical support from DHANES, to help spread the reach of the survey and provide more granular data. This could be especially helpful for areas such as Hawaii, Alaska, and Puerto Rico, where data are lacking. One option to consider is a “mini-NHANES” approach in which smaller state-based surveys are conducted in the model of the national survey.

Finally, participants offered ideas for ways to enhance and empower the community of researchers who use NHANES data. They pointed to the need to better educate graduate students on how to use these important data, which would require funding as well as curriculum development. Although many participants emphasized the importance of making NHANES data easier to access, some cautioned that it remains important for users to understand how to use the data properly.

Overall, the workshop highlighted both challenges and opportunities in charting a path forward for NHANES (Table 2). Participants recognized the essential role the survey plays in advancing United States public health efforts by providing scientific insights and informing health policies overall, and for nutrition research in particular. They also identified ways to sustain that role into the future by improving response rates, increasing efficiency, and ensuring that the data generated are easier to access and available faster.

TABLE 2.

Gaps and future opportunities for NHANES

Theme	Research gaps	Future opportunities
Response rates of underrepresented groups	•Selective oversampling of certain subgroups and not others may lead to data gaps. For example, a subgroup of a minority population may be oversampled (e.g., Mexican American), but other subgroups are not oversampled (e.g., Puerto Ricans) leading to data gaps •Data needed from pregnant and lactating participants, and older groups	•Rotation through certain ethnic minority subgroups (e.g., Puerto Ricans) in various cycles could provide useful granular-level data •Community engagement as a strategy to engage underrepresented groups •Reduce survey participant burden through use of apps, wearables, and other tools to facilitate remote data collection •Improvements in communication and marketing of NHANES (e.g., as either a general health survey or a chronic disease survey)
Data linkages	•Timely dietary intake data, and in particular usual intake data per cycle and per 4–6 y of data for certain subgroup analyses •Linkage of the Healthy Eating Index totals and subscores with participants rather than relying on research community to perform coding	•Nutrient density metrics and further delineation of foods such as minimally and ultraprocessed foods •Linkage of survey data with additional data sources such as grocery receipts, other food sales data, school test scores, and environmental impact databases •Food costs need to be updated with each NHANES cycle
New survey methodologies	•Need for more remote, web-based data collection tools (e.g., ASA24)	•Combination of in-person or phone-based interviews to accommodate the diversity of the study population •Use of image-based methods to assess dietary intake
Emerging data needs	•Administrative hurdles involved in identifying and navigating the necessary data centers	•New biomarkers to improve data quality (e.g., correct errors in self-reported data)

Abbreviation: ASA24, Automated Self-Administered 24-H Dietary Assessment Tool.

Acknowledgments

We thank the members of the ASN CASP for organizing the workshop and reviewing the summary report. We also thank each of the workshop speakers, panelists, and moderators.

Author contributions

The authors’ responsibilities were as follows – AFJ, NL: were responsible for initial drafts of the manuscript; and all authors: contributed to the text and figures and read and approved the final manuscript.

Conflict of interest

AFJ and NL are employees of Creative Science Writing, paid by ASN to develop this summary report. SDO is an ASN employee. CDR is an employee of PepsiCo, Inc. The views expressed in this article are those of the authors and do not necessarily represent the position or policy of PepsiCo, Inc. or the official views of the National Heart, Lung, and Blood Institute, the National Institutes of Health or the United States Department of Health and Human Services. All other authors have no conflicts of interest to report.

Funding

ASN contracted with and provided financial support to Creative Science Writing to develop this summary report.