Plan and Operations of the National Health and Nutrition Examination Survey, August 2021-August 2023.

The continuous National Health and Nutrition Examination Survey began data collection in 1999 and proceeded without interruption until operations were suspended in March 2020 in response to the COVID-19 pandemic. Once the Division of Health and Nutrition Examination Surveys was able to determine and resume safe field operations, the next survey cycle was conducted between August 2021 and August 2023. This report describes the survey content, procedures, and methodologies implemented in the August 2021-August 2023 National Health and Nutrition Examination Survey cycle.

Reasons for Nonparticipation in the Special Supplemental Nutrition Program for Women, Infants, and Children.

This cross-sectional study evaluates reasons reported for not participating in or withdrawing participation from the Special Supplemental Nutrition Program for Women, Infants, and Children from 2019 to March 2020.

Trends in Food Consumption Among Children Aged 1-4 Years by Participation in the Special Supplemental Nutrition Program for Women, Infants, and Children, United States, 2005-2018.

BACKGROUND: In 2009, the US Department of Agriculture Food and Nutrition Service's Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) food packages were revised to include more whole fruits, vegetables, whole grains, and lower-fat milk. OBJECTIVE: The aim of this study was to describe trends over time in the consumption of fruits (total and whole), vegetables, whole grains, milk (whole, reduced fat, low-fat or nonfat (LFNF), and flavored), and added sugars, including breakfast cereals, by WIC participation status (current WIC recipient, WIC income-eligible nonrecipient, and WIC income-ineligible nonrecipient). METHODS: Dietary intakes on a given day for 1- to 4-y-old children (n = 5568) from the 2005-2018 National Health and Nutrition Examination Survey (NHANES) were analyzed to examine trends in the percentage of individuals consuming and amounts consumed over time using linear regression adjusted for age, sex, and race and Hispanic origin. RESULTS: From 2005 through 2018, the percentage of WIC recipients or WIC income-eligible nonrecipients consuming fruits and vegetables on a given day did not change, but the percentage of fruit consumed as whole fruit increased significantly among WIC recipients (36.4%-62.1%), but not among income-eligible nonrecipients. Among the WIC recipients, the percentage of consumption (5.5%-29.3%), the amount of LFNF milk servings consumed (0.1-0.4 cups), and the percentage of the total milk consumed as LFNF milk (4.8%-27%) significantly increased from 2005 to 2018. Conversely, the percentage of energy (12.3%-10.8%) and servings (11.4-10.6 teaspoons) from added sugars declined significantly. Among WIC-eligible nonrecipients, the servings of whole grains increased significantly, whereas servings and percentage of energy from added sugars declined significantly. CONCLUSIONS: From 2005 through 2018, changes in dietary patterns for WIC recipients did not always mirror those of US children of the same age. The percentage of fruit consumed as whole fruit, and the percentage and quantity of milk consumed as LFNF milk increased significantly among WIC recipients, but not among income-eligible nonrecipients. J Nutr 20XX;xx:xx-xx.

Breakfast Intake Among Children and Adolescents: United States, 2015-2018.

The American Academy of Pediatrics recommends that children and adolescents consume breakfast for healthier body weights, improved nutrition, better memory, better test scores, and better attention spans (1). This report describes breakfast consumption among children and adolescents by sex, age, race and Hispanic origin, and family income level. Foods and beverages frequently consumed for breakfast, as well as trends in breakfast consumption over the last decade, are also reported.

Contribution of Whole Grains to Total Grains Intake Among Adults Aged 20 and Over: United States, 2013-2016.

Total grains intake comes from whole grains and refined grains. Whole grains contain the entire grain kernel (bran, germ, and endosperm) (1). A higher intake of whole grains is linked with a lower risk of cardiovascular disease, cancer, and mortality (2). The "2015-2020 Dietary Guidelines for Americans" recommend that at least one-half of total grains intake be from whole grains (3). This report provides estimates of the percentage of total grains intake consumed from whole grains sources, for adults aged 20 and over who reported consumption of grains (98.6%) on a given day during 2013-2016.

Evaluation of measurement error in 24-hour dietary recall for assessing sodium and potassium intake among US adults - National Health and Nutrition Examination Survey (NHANES), 2014.

BACKGROUND: Understanding measurement error in sodium and potassium intake is essential for assessing population intake and studying associations with health outcomes. OBJECTIVE: The aim of this study was to compare sodium and potassium intake derived from 24-h dietary recall (24HDR) with intake derived from 24-h urinary excretion (24HUE). DESIGN: Data were analyzed from 776 nonpregnant, noninstitutionalized US adults aged 20-69 y who completed 1-to-2 24HUE and 24HDR measures in the 2014 NHANES. A total of 1190 urine specimens and 1414 dietary recalls were analyzed. Mean bias was estimated as mean of the differences between individual mean 24HDR and 24HUE measurements. Correlations and attenuation factors were estimated using the Kipnis joint-mixed effects model accounting for within-person day-to-day variability in sodium excretion. The attenuation factor reflects the degree to which true associations between long-term intake (estimated using 24HUEs) and a hypothetical health outcome would be approximated using a single 24HDR: values near 1 indicate close approximation and near 0 indicate bias toward null. Estimates are reported for sodium, potassium, and the sodium: potassium (Na/K) ratio. Model parameters can be used to estimate correlations/attenuation factors when multiple 24HDRs are available. RESULTS: Overall, mean bias for sodium was -452 mg (95% CI: -646, -259), for potassium -315 mg (CI: -450, -179), and for the Na/K ratio -0.04 (CI: -0.15, 0.07, NS). Using 1 24HDR, the attenuation factor for sodium was 0.16 (CI: 0.09, 0.21), for potassium 0.25 (CI:0.16, 0.36), and for the Na/K ratio 0.20 (CI: 0.10, 0.25). The correlation for sodium was 0.27 (CI: 0.16, 0.37), for potassium 0.35 (CI: 0.26, 0.55), and for the Na/K ratio 0.27 (CI: 0.13, 0.32). CONCLUSIONS: Compared with 24HUE, using 24HDR underestimates mean sodium and potassium intake but is unbiased for the Na/K ratio. Additionally, using 24HDR as a measure of exposure in observational studies attenuates the true associations of sodium and potassium intake with health outcomes.

Association of usual 24-h sodium excretion with measures of adiposity among adults in the United States: NHANES, 2014.

Background: Both excessive sodium intake and obesity are risk factors for hypertension and cardiovascular disease. The association between sodium intake and obesity is unclear, with few studies assessing sodium intake using 24-h urine collection. Objectives: Our objective was to assess the association between usual 24-h sodium excretion and measures of adiposity among US adults. Methods: Cross-sectional data were analyzed from a sample of 730 nonpregnant participants aged 20-69 y who provided up to 2 complete 24-h urine specimens in the NHANES 2014 and had data on overweight or obesity [body mass index (kg/m2) ≥25] and central adiposity [waist circumference (WC): >88 cm for women, >102 cm for men]. Measurement error models were used to estimate usual sodium excretion, and multiple linear and logistic regression models were used to assess its associations with measures of adiposity, adjusting for sociodemographic, health, and dietary variables [i.e., energy intake or sugar-sweetened beverage (SSB) intake]. All analyses accounted for the complex survey sample design. Results: Unadjusted mean ± SE usual sodium excretion was 3727 ± 43.5 mg/d and 3145 ± 55.0 mg/d among participants with and without overweight/obesity and 3653 ± 58.1 mg/d and 3443 ± 35.3 mg/d among participants with or without central adiposity, respectively. A 1000-mg/d higher sodium excretion was significantly associated with 3.8-units higher BMI (95% CI: 2.8, 4.8) and a 9.2-cm greater WC (95% CI: 6.9, 11.5 cm) adjusted for covariates. Compared with participants in the lowest quartile of sodium excretion, the adjusted prevalence ratios in the highest quartile were 1.93 (95% CI: 1.69, 2.20) for overweight/obesity and 2.07 (95% CI: 1.74, 2.46) for central adiposity. The associations also were significant when adjusting for SSBs, instead of energy, in models. Conclusions: Higher usual sodium excretion is associated with overweight/obesity and central adiposity among US adults.

Seafood Consumption in the United States, 2013-2016.

The 2015-2020 Dietary Guidelines for Americans (1) recommend consuming two servings of seafood, including fish and shellfish, per week. Consuming approximately 8 ounces of a variety of seafood weekly is associated with reduced cardiac deaths (2). This report describes the percentage of U.S. adults and youth who reported consuming seafood at least two times per week by sex, age, and race and Hispanic origin during 2013-2016. Trends in the percentage of adults and youth who consumed seafood at least twice weekly, from 2005-2006 through 2015-2016, are also presented.

Beverage Consumption Among Youth in the United States, 2013-2016.

Beverages contribute to hydration and affect total calorie intake (1). For all individuals aged 2 years and over, the 2015-2020 Dietary Guidelines for Americans recommend that water, fat-free and low-fat milk, and 100% juice be the primary beverages consumed (2). The American Academy of Pediatrics also supports this advice for youth (3). This report describes the contribution of different beverage types to total beverage consumption, by grams, among U.S. youth.

Estimated 24-Hour Urinary Sodium and Potassium Excretion in US Adults.

Importance: In 2010, the Institute of Medicine (now the National Academy of Medicine) recommended collecting 24-hour urine to estimate US sodium intake because previous studies indicated 90% of sodium consumed was excreted in urine. Objective: To estimate mean population sodium intake and describe urinary potassium excretion among US adults. Design, Setting, and Participants: In a nationally representative cross-sectional survey of the US noninstitutionalized population, 827 of 1103 (75%) randomly selected, nonpregnant participants aged 20 to 69 years in the examination component of the National Health and Nutrition Examination Survey (NHANES) collected at least one 24-hour urine specimen in 2014. The overall survey response rate for the 24-hour urine collection was approximately 50% (75% [24-hour urine component response rate] × 66% [examination component response rate]). Exposures: 24-hour collection of urine. Main Outcomes and Measures: Mean 24-hour urinary sodium and potassium excretion. Weighted national estimates of demographic and health characteristics and mean electrolyte excretion accounting for the complex survey design, selection probabilities, and nonresponse. Results: The study sample (n = 827) represented a population of whom 48.8% were men; 63.7% were non-Hispanic white, 15.8% Hispanic, 11.9% non-Hispanic black, and 5.6% non-Hispanic Asian; 43.5% had hypertension (according to 2017 hypertension guidelines); and 10.0% reported a diagnosis of diabetes. Overall mean 24-hour urinary sodium excretion was 3608 mg (95% CI, 3414-3803). The overall median was 3320 mg (interquartile range, 2308-4524). In secondary analyses by sex, mean sodium excretion was 4205 mg (95% CI, 3959-4452) in men (n = 421) and 3039 mg (95% CI, 2844-3234) in women (n = 406). By age group, mean sodium excretion was 3699 mg (95% CI, 3449-3949) in adults aged 20 to 44 years (n = 432) and 3507 mg (95% CI, 3266-3748) in adults aged 45 to 69 years (n = 395). Overall mean 24-hour urinary potassium excretion was 2155 mg (95% CI, 2030-2280); by sex, 2399 mg (95% CI, 2253-2545) in men and 1922 mg (95% CI, 1757-2086) in women; and by age, 1986 mg (95% CI, 1878-2094) in adults aged 20 to 44 years and 2343 mg (95% CI, 2151-2534) in adults aged 45 to 69 years. Conclusions and Relevance: In cross-sectional data from a 2014 sample of US adults, estimated mean sodium intake was 3608 mg per day. The findings provide a benchmark for future studies.

Association Between Urinary Sodium and Potassium Excretion and Blood Pressure Among Adults in the United States: National Health and Nutrition Examination Survey, 2014.

BACKGROUND: Higher levels of sodium and lower levels of potassium intake are associated with higher blood pressure. However, the shape and magnitude of these associations can vary by study participant characteristics or intake assessment method. Twenty-four-hour urinary excretion of sodium and potassium are unaffected by recall errors and represent all sources of intake, and were collected for the first time in a nationally representative US survey. Our objective was to assess the associations of blood pressure and hypertension with 24-hour urinary excretion of sodium and potassium among US adults. METHODS: Cross-sectional data were obtained from 766 participants age 20 to 69 years with complete blood pressure and 24-hour urine collections in the 2014 National Health and Nutrition Examination Survey, a nationally representative survey of the US noninstitutionalized population. Usual 24-hour urinary electrolyte excretion (sodium, potassium, and their ratio) was estimated from ≤2 collections on nonconsecutive days, adjusting for day-to-day variability in excretion. Outcomes included systolic and diastolic blood pressure from the average of 3 measures and hypertension status, based on average blood pressure ≥140/90 and antihypertensive medication use. RESULTS: After multivariable adjustment, each 1000-mg difference in usual 24-hour sodium excretion was directly associated with systolic (4.58 mm Hg; 95% confidence interval [CI], 2.64-6.51) and diastolic (2.25 mm Hg; 95% CI, 0.83-3.67) blood pressures. Each 1000-mg difference in potassium excretion was inversely associated with systolic blood pressure (-3.72 mm Hg; 95% CI, -6.01 to -1.42). Each 0.5 U difference in sodium-to-potassium ratio was directly associated with systolic blood pressure (1.72 mm Hg; 95% CI, 0.76-2.68). Hypertension was linearly associated with progressively higher sodium and lower potassium excretion; in comparison with the lowest quartile of excretion, the adjusted odds of hypertension for the highest quartile was 4.22 (95% CI, 1.36-13.15) for sodium, and 0.38 (95% CI, 0.17-0.87) for potassium (P<0.01 for trends). CONCLUSIONS: These cross-sectional results show a strong dose-response association between urinary sodium excretion and blood pressure, and an inverse association between urinary potassium excretion and blood pressure, in a nationally representative sample of US adults.

Sodium Intake Among Persons Aged ≥2 Years - United States, 2013-2014.

High sodium consumption can increase hypertension, a major risk factor for cardiovascular diseases (1). Reducing sodium intake can lower blood pressure, and sodium reduction in the U.S. population of 40% over 10 years might save at least 280,000 lives (2). Average sodium intake in the United States remains in excess of Healthy People 2020 objectives,* and monitoring sources of sodium in the U.S. population can help focus sodium reduction measures (3,4). Data from 2013-2014 What We Eat in America (WWEIA), the dietary intake portion of the National Health and Nutrition Examination Survey (NHANES),† were analyzed to determine the ranked percentage sodium contribution of selected food categories and sources of sodium intake from all reported foods and beverages, both overall and by demographic subgroups. These latest data include updated food codes and separate estimates for intake among non-Hispanic Asians.§ In 2013-2014, 70% of dietary sodium consumed by persons in the United States came from 25 food categories; breads were the top contributor, accounting for 6% of sodium consumed. A majority of sodium consumed was from food obtained at stores; however, sodium density (mg/1,000 kcal) was highest in food obtained at restaurants. A variety of commonly consumed foods contributes to U.S. sodium intake, emphasizing the importance of sodium reduction across the food supply (4).

Feasibility of collecting 24-h urine to monitor sodium intake in the National Health and Nutrition Examination Survey.

BACKGROUND: Twenty-four-hour urine sodium excretion is recommended for monitoring population sodium intake. Because of concerns about participation and completion, sodium excretion has not been collected previously in US nationally representative surveys. OBJECTIVE: We assessed the feasibility of implementing 24-h urine collections as part of a nationally representative survey. DESIGN: We selected a random half sample of nonpregnant US adults aged 20-69 y in 3 geographic locations of the 2013 NHANES. Participants received explicit instructions, started and ended the urine collection in a urine study mobile examination center, and answered questions about their collection. Among those with a complete 24-h urine collection, a random one-half were asked to collect a second 24-h urine sample. Sodium, potassium, chloride, and creatinine excretion were analyzed. RESULTS: The final NHANES examination response rate for adults aged 20-69 y in these 3 study locations was 71%. Of those examined (n = 476), 282 (59%) were randomly selected to participate in the 24-h urine collection. Of these, 212 persons [75% of those selected for 24-h urine collection; 53% (equal to 71% × 75% of those selected for the NHANES)] collected a complete initial 24-h specimen and 92 persons (85% of 108 selected) collected a second complete 24-h urine sample. More men than women completed an initial collection (P = 0.04); otherwise, completion did not vary by sociodemographic characteristics, body mass index, education, or employment status for either collection. Mean 24-h urine volume and sodium excretion were 1964 ± 1228 mL and 3657 ± 2003 mg, respectively, for the first 24-h urine sample, and 2048 ± 1288 mL and 3773 ± 1891 mg, respectively, for the second collection. CONCLUSION: Given the 53% final component response rate and 75% completion rate, 24-h urine collections were deemed feasible and implemented in the NHANES 2014 on a subsample of adults aged 20-69 y to assess population sodium intake. This study was registered at clinicaltrials.gov as NCT02723682.

Collection and laboratory methods for dried blood spots for hemoglobin A1c and total and high-density lipoprotein cholesterol in population-based surveys.

BACKGROUND: The Health Measures at Home Study was a study designed to evaluate the feasibility of incorporating dried blood spots (DBS) collection into the National Health Interview Survey and to compare the proficiencies between field interviewers and health technicians in obtaining DBS. METHODS: DBS collection and venipuncture were attempted on 125 participants. The DBS were collected in the participant's home and venous blood was collected in the National Health and Nutrition Examination Survey (NHANES) mobile examination center. The DBS results were compared to venous results in the NHANES for the measurements of hemoglobin A1c (HbA1c) and total and high-density lipoprotein (HDL) cholesterol. RESULTS: Field interviewers and health technicians were able to collect the DBS for greater than 95% of participants. For DBS, health technicians and field interviewers were highly correlated for HbA1c (r=0.92) and total cholesterol (r=0.89), but not for HDL cholesterol (r=0.72). The DBS results of interviewers and health technicians compared to the venous method for HbA1c (r=0.90), but did not compare well for HDL cholesterol (r=0.64-0.66) and total cholesterol (r=0.65-0.67). CONCLUSION: DBS was comparable to venous HbA1c, but not for total and HDL cholesterol. Health technicians and field interviewers had similar performance for DBS methods, except HDL cholesterol.

Comparison of in-home collection of physical measurements and biospecimens with collection in a standardized setting: the health measures at home study.

OBJECTIVES: Collection of physical measurements and biospecimens in the home may be an efficient way to obtain objective health measurements. This study assesses differences between collection in the home and a standardized setting. METHODS: Participants had physical measurements and biospecimens taken in the National Health and Nutrition Examination Survey mobile examination center (MEC). Then, they had height and weight measured in the MEC using portable equipment. In the home, participants had height, weight, and blood pressure measured and dried blood spots collected using portable equipment. Two complete examinations were done in the home: one by a health technician and one by a field interviewer. RESULTS: Home environments were less standardized and presented more challenges to examiners. Correlations between all four height measurements and all four weight measurements were higher than 99%. Mean differences in height (0.3 cm) and weight (0.4 kg) were small but statistically significant. The home measurements perfectly or near-perfectly classified participants as obese relative to the standardized MEC examination. CONCLUSIONS: The selected physical measurements can be collected in the home by field interviewers using portable equipment. Before adding home collection of physical measurements to household interview surveys, further research should be done to examine the impact of these changes on interviewer training, participant recruitment, and participant response rates.

The methodology of visual field testing with frequency doubling technology in the National Health and Nutrition Examination Survey, 2005-2006.

PURPOSE: To describe the frequency doubling technology (FDT) methodology to measure visual field loss in the National Health and Nutrition Examination Survey and to evaluate data reliability. METHODS: Participants aged 40 years and older were eligible (n = 2,529) for 2 visual field tests per eye performed with the Humphrey Matrix N-30-5 screening test. Visual field loss was determined using a 2-2-1 algorithm requiring 2 complete tests per eye, with at least 2 abnormal field results in each test, and 1 common abnormal field. RESULTS: Response rate was 86.2%. Time constraints were the main reason for no exam (55.6%). Median times were: single test, 37 seconds; entire exam, 9.1 minutes. When defining reliability based on ≤ 1/3 blind spots, ≤ 1/3 false positive tests, and technician noted proper fixation, 80.1% of examined adults had 2 reliable tests for both eyes; an additional 13.4% had 2 reliable tests for 1 eye. Increasing age, decreasing visual acuity, and the presence of self-reported glaucoma resulted in decreased examination rates, increased test times, and decreased data reliability. Sensitivity and specificity to detect persons with glaucoma was 54.8% and 91.9%, respectively. CONCLUSIONS: FDT is a feasible, fast, and reliable method for visual field loss screening in a population-based U.S. study, with an 86.2% response rate, median exam time ~9 minutes, and nearly 95% of examined participants having complete, reliable results in 1 or both eyes.