Nutrition assessment in the National Health And Nutrition Examination Survey 1999-2002

The objective of this study is to describe the components of nutrition assessment in the National Health and Nutrition Examination Survey (NHANES) 1999-2002. The study design was a cross-sectional survey with a nationally representative sample of the US population. The survey participants were interviewed and completed a physical examination. From 1999 to 2002, a total of 25,316 people were included in the eligible sample, 21,004 people (83%) were interviewed, and 19,759 people (78% of the eligible sample) were examined. Dietary assessment consisted of a 24-hour dietary recall interview and questions on supplement use, food security, food-program participation, and other behaviors. Nutrition assessment included anthropometric measurements and body-composition assessment. A number of nutrition biochemistries were measured in blood and urine specimens. In addition, an assessment of cardiovascular fitness and questions on physical activity were included. Data are used to estimate population reference distributions and to monitor trends over time. Data have been used to evaluate the adequacy of nutrient intake using the Dietary Reference Intakes, to assist in development of nutrition policies related to obesity, and to evaluate policies such as folic acid fortification. The NHANES contributes to the knowledge and understanding of nutrition and health status in the US population through public-use microdata files for use by researchers in academia, in the private sector, and in government agencies. Continuous data collection will allow the NHANES to provide more timely information for policy development and evaluation.     

Cadmium exposure and hypertension in the 1999-2004 National Health and Nutrition Examination Survey (NHANES)

INTRODUCTION: Cadmium induces hypertension in animal models. Epidemiologic studies of cadmium exposure and hypertension, however, have been inconsistent. OBJECTIVE: We aimed to investigate the association of blood and urine cadmium with blood pressure levels and with the prevalence of hypertension in U.S. adults who participated in the 1999-2004 National Health and Nutrition Examination Survey (NHANES). METHODS: We studied participants > or = 20 years of age with determinations of cadmium in blood (n = 10,991) and urine (n = 3,496). Blood and urine cadmium were measured by atomic absorption spectrometry and inductively coupled plasma-mass spectrometry, respectively. Systolic and diastolic blood pressure levels were measured using a standardized protocol. RESULTS: The geometric means of blood and urine cadmium were 3.77 nmol/L and 2.46 nmol/L, respectively. After multivariable adjustment, the average differences in systolic and diastolic blood pressure comparing participants in the 90th vs. 10th percentile of the blood cadmium distribution were 1.36 mmHg [95% confidence interval (CI), -0.28 to 3.00] and 1.68 mmHg (95% CI, 0.57-2.78), respectively. The corresponding differences were 2.35 mmHg and 3.27 mmHg among never smokers, 1.69 mmHg and 1.55 mmHg among former smokers, and 0.02 mmHg and 0.69 mmHg among current smokers. No association was observed for urine cadmium with blood pressure levels, or for blood and urine cadmium with the prevalence of hypertension. CONCLUSIONS: Cadmium levels in blood, but not in urine, were associated with a modest elevation in blood pressure levels. The association was stronger among never smokers, intermediate among former smokers, and small or null among current smokers. Our findings add to the concern of renal and cardiovascular cadmium toxicity at chronic low levels of exposure in the general population.     

Dietary supplement use by US adults: data from the National Health and Nutrition Examination Survey, 1999-2000

Data from the 1999-2000 National Health and Nutrition Examination Survey, a nationally representative, cross-sectional survey of US health and nutrition, were analyzed to assess prevalence of dietary supplement use overall and in relation to lifestyle and demographic characteristics. Fifty-two percent of adults reported taking a dietary supplement in the past month; 35% took a multivitamin/multimineral. Vitamin C, vitamin E, B-complex vitamins, calcium, and calcium-containing antacids were taken by more than 5% of adults. In bivariate analyses, female gender, older age, more education, non-Hispanic White race/ethnicity, any physical activity, normal/underweight, more frequent wine or distilled spirit consumption, former smoking, and excellent/very good self-reported health were associated with greater use of any supplement and of multivitamin/multiminerals; in multivariable comparisons, the latter three characteristics were not associated with supplement use. Most supplements were taken daily and for at least 2 years. Forty-seven percent of adult supplement users took just one supplement; 55% of women and 63% of adults aged >or=60 years took more than one. These findings suggest that, to minimize possible spurious associations, epidemiologic studies of diet, demography, or lifestyle and health take dietary supplement use into account because of 1) supplements' large contribution to nutrient intake and 2) differential use of supplements by demographic and lifestyle characteristics.     

Association of total calcium and dietary protein intakes with fracture risk in postmenopausal women: The 1999–2002 National Health and Nutrition Examination Survey (NHANES)

ObjectiveWe examined the associations of total calcium intake (TCI) and dietary protein intake (DPI) with risk of fracture.MethodsA total of 2006 postmenopausal women ≥50 y of age who were measured in the 1999–2002 National Health and Nutrition Examination Survey were included in the study. Weighted mean TCI and DPI and percentage of distributions of selected characteristics were estimated by TCI category and fracture status. Multivariate logistic regression models were used to assess the effect of TCI and DPI on risk of fracture.ResultsThirteen percent of participants reported a fracture history, of whom 17.8% consumed a total of ≥1200 mg of calcium per day and 23.8% consumed <400 mg/d. TCI was not associated with fracture risk when controlling for all selected covariates. In women who consumed <46 g/d of dietary protein, those with a TCI ≥1200 mg/d had a significantly higher risk of fracture than those with the lowest TCI (adjusted odds ratio 5.98, 95% confidence interval 1.15–31.13), whereas in women who consumed >70 g/d of dietary protein, those with a TCI ≥1200 mg/d had an insignificant lower risk of fracture (adjusted odds ratio 0.69, 95% confidence interval 0.20–2.39).ConclusionTCI is not associated with risk of fracture among postmenopausal women. Adequate TCI in the presence of inadequate DPI may not be protective against fractures. Optimal proportion of TCI and DPI warrants further investigation among older women.     

Carbohydrate intake and biomarkers of glycemic control among US adults: the third National Health and Nutrition Examination Survey (NHANES III)

BACKGROUND: Recommendations for preventing and treating type 2 diabetes include consuming carbohydrates, predominantly from whole grains, fruit, vegetables, and low-fat milk. However, the quantity and type of carbohydrates consumed may contribute to disorders of glycemic control. OBJECTIVE: We evaluated the association between carbohydrate intakes and biomarkers of glycemic control in a nationally representative sample of healthy US adults who participated in a cross-sectional study, the third National Health and Nutrition Examination Survey. DESIGN: The sample (5730 men and 6125 women aged > or = 20 y) was divided into quintiles of carbohydrate intake (as a percentage of energy). Carbohydrate intakes were examined in relation to glycated hemoglobin (Hb A(1c)), plasma glucose, serum C-peptide, and serum insulin concentrations by using logistic regression. RESULTS: Carbohydrate intakes were not associated with Hb A(1c), plasma glucose, or serum insulin concentrations in men or women after adjustment for confounding variables. Carbohydrate intakes were inversely associated with serum C-peptide concentrations in men and women. Odds ratios for elevated serum C-peptide concentrations for increasing quintiles of carbohydrate intake were 1.00, 0.88, 0.57, 0.39, and 0.75 (P for trend = 0.016) in men, and 1.00, 0.69, 0.57, 0.36, and 0.41 (P for trend = 0.007) in women. When carbohydrate intakes were further adjusted for intakes of total and added sugar, the association of serum C-peptide with carbohydrate intakes was strengthened in men. CONCLUSIONS: Carbohydrate intakes were not associated with Hb A(1c), plasma glucose, or serum insulin concentrations but were inversely associated with the risk of elevated serum C-peptide; this supports current recommendations regarding carbohydrate intake in healthy adults.     

Association between appendicular skeletal muscle index and leukocyte telomere length in adults: A study from National Health and Nutrition Examination Survey (NHANES) 1999–2002

In young people with preserved muscle mass, for every 1 kg/m² increase in the ASMI, telomere will be extended by 82.6 bp; this would equate to 5.4 fewer years of biological aging (82.6 base pairs/15.3).

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Out-of-hand nut consumption is associated with improved nutrient intake and health risk markers in US children and adults: National Health and Nutrition Examination Survey 1999-2004

The purpose of this study was to determine the association of out-of-hand nut (OOHN) consumption with nutrient intake, diet quality, and the prevalence of risk factors for cardiovascular disease and metabolic syndrome. Data from 24-hour recalls from individuals aged 2+ years (n = 24?385) participating in the 1999-2004 National Health and Nutrition Examination Survey were used. The population was divided into children aged 2 to 11, 12 to 18, and adults 19+ years, and each group was dichotomized into OOHN consumers and nonconsumers. Out-of-hand nut consumers were defined as those individuals consuming ¼ oz of nuts or more per d. Means, standard errors, and covariate-adjusted analyses of variance were determined using appropriate sample weights. Diet quality was determined using the Healthy Eating Index-2005. Significance was set at P < .05. The percent of OOHN consumers increased with age: 2.1% ± 0.3%, 2.6% ± 0.3%, 6.5% ± 0.5%, and 9.6% ± 0.5% those aged 2 to 11, 12 to 18, 19 to 50, and 51+ years, respectively. The 2 latter groups were combined into a single group of consumers aged 19+ years for subsequent analyses. Consumers of OOHN from all age groups had higher intakes of energy, monounsaturated and polyunsaturated fatty acids, dietary fiber, copper, and magnesium and lower intakes of carbohydrates, cholesterol, and sodium than did nonconsumers. Diet quality was higher in OOHN consumers of all age groups. In children aged 2 to 11 years, consumers had a higher prevalence of overweight/obesity. In those aged 12 to 18 years, weight and percent overweight were lower in consumers. Adult consumers had higher high-density lipoprotein cholesterol, red blood cell folate, and serum folate levels and lower insulin, glycohemoglobin, and C-reactive protein levels than did nonconsumers. Adult consumers also had a 19% decreased risk of hypertension and a 21% decreased risk of low high-density lipoprotein cholesterol levels. Data suggested that OOHN consumption was associated with improved nutrient intake, diet quality, and, in adults, a lower prevalence of 2 risk factors for metabolic syndrome. Consumption of OOHN, as part of a healthy diet, should be encouraged by health professionals.     

Polyfluoroalkyl chemicals in the U.S. population: data from the National Health and Nutrition Examination Survey (NHANES) 2003-2004 and comparisons with NHANES 1999-2000

BACKGROUND: Polyfluoroalkyl chemicals (PFCs) have been used since the 1950s in numerous commercial applications. Exposure of the general U.S. population to PFCs is widespread. Since 2002, the manufacturing practices for PFCs in the United States have changed considerably. OBJECTIVES: We aimed to assess exposure to perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonic acid (PFHxS), perfluorononanoic acid (PFNA), and eight other PFCs in a representative 2003-2004 sample of the general U.S. population >or= 12 years of age and to determine whether serum concentrations have changed since the 1999-2000 National Health and Nutrition Examination Survey (NHANES). METHODS: By using automated solid-phase extraction coupled to isotope dilution-high-performance liquid chromatography-tandem mass spectrometry, we analyzed 2,094 serum samples collected from NHANES 2003-2004 participants. RESULTS: We detected PFOS, PFOA, PFHxS, and PFNA in > 98% of the samples. Concentrations differed by race/ethnicity and sex. Geometric mean concentrations were significantly lower (approximately 32% for PFOS, 25% for PFOA, 10% for PFHxS) and higher (100%, PFNA) than the concentrations reported in NHANES 1999-2000 (p < 0.001). CONCLUSIONS: In the general U.S. population in 2003-2004, PFOS, PFOA, PFHxS, and PFNA serum concentrations were measurable in each demographic population group studied. Geometric mean concentrations of PFOS, PFOA, and PFHxS in 2003-2004 were lower than in 1999-2000. The apparent reductions in concentrations of PFOS, PFOA, and PFHxS most likely are related to discontinuation in 2002 of industrial production by electrochemical fluorination of PFOS and related perfluorooctanesulfonyl fluoride compounds.     

Dried fruit consumption is associated with improved diet quality and reduced obesity in US adults: National Health and Nutrition Examination Survey, 1999-2004

Epidemiological studies examining potential associations between dried fruit consumption, diet quality, and weight status are lacking. The goal of this study was to examine the association of dried fruit consumption with nutrient intake, diet quality, and anthropometric indicators of overweight/obesity. A secondary analysis of dietary and anthropometric data collected from adult (19+ years) participants (n = 13 292) of the 1999-2004 National Health and Nutrition Examination Survey was conducted. Dried fruit consumers were defined as those consuming amounts ? cup-equivalent fruit per day or more and identified using 24-hour recalls. Diet quality was measured using the Healthy Eating Index 2005. Covariate-adjusted means, SEs, prevalence rates, and odds ratios were determined to conduct statistical tests for differences between dried fruit consumers and nonconsumers. Seven percent of the population consumed dried fruit. Mean differences (P < .01) between consumers and nonconsumers in adult shortfall nutrients were dietary fiber (+6.6 g/d); vitamins A (+173 μg retinol activity equivalent per day), E (+1.5 mg α-tocopherol per day), C (+20 mg/d), and K (+20 mg/d); calcium (+103 mg/d); phosphorus (+126 mg/d); magnesium (+72 mg/d); and potassium (+432 mg/d). Dried fruit consumers had improved MyPyramid food intake, including lower solid fats/alcohol/added sugars intake, and a higher solid fats/alcohol/added sugars score (11.1 ± 0.2 vs 8.2 ± 0.1) than nonconsumers. The total Healthy Eating Index 2005 score was significantly higher (P < .01) in consumers (59.3 ± 0.5) than nonconsumers (49.4 ± 0.3). Covariate-adjusted weight (78.2 ± 0.6 vs 80.7 ± 0.3 kg), body mass index (27.1 ± 0.2 vs 28.1 ± 0.2), and waist circumference (94.0 ± 0.5 vs 96.5 ± 0.2 cm) were lower (P < .01) in consumers than nonconsumers, respectively. Dried fruit consumption was associated with improved nutrient intakes, a higher overall diet quality score, and lower body weight/adiposity measures.     

Acculturation and diabetes among Hispanics: evidence from the 1999-2002 National Health and Nutrition Examination Survey

OBJECTIVE: Hispanic individuals in the United States have a greater prevalence of diabetes mellitus than non-Hispanic white individuals; however, it is unclear whether Hispanics' risk of diabetes differs based on their level of acculturation. The purpose of our research was to examine acculturation among Hispanic Americans with respect to prevalence and control of diabetes. METHODS: We conducted an analysis of the National Health and Nutrition Examination Survey (NHANES), 1999-2002, a nationally representative sample of the noninstitutionalized U.S. population. We evaluated data on Hispanic adults (> or = 18 years of age, unweighted n=2,696), analyzing diagnosed diabetes, glycemic blood pressure and lipid control, and diabetes complications according to acculturation as measured by language and birth outside the United States. RESULTS: Hispanics with low acculturation were more likely to be without a routine place for health care, have no health insurance, and have low levels of education. In adjusted analyses, individuals with low acculturation, measured by language, were more likely to have diabetes (odds ratio [OR] 1.90, 95% confidence interval [CI] 1.02, 3.54). Among individuals with diagnosed diabetes, no significant association was yielded between acculturation and diabetes control. However, individuals with low language acculturation were more likely to have the diabetes complication of peripheral neuropathy (OR 4.01, 95% CI 1.40, 11.48). CONCLUSIONS: Acculturation as measured through language is associated with diabetes and complications among Hispanics even after controlling for a variety of demographic characteristics including health insurance and education. The findings suggest that even within a "single" minority ethnic group, there are differences in disease prevalence and complications and access to health care.     

Association of polychlorinated biphenyls with hypertension in the 1999-2002 National Health and Nutrition Examination Survey

The association of 11 polychlorinated biphenyls (PCBs) with hypertension was investigated using the National Health and Nutrition Examination Survey (NHANES), 1999-2002. The unweighted number of participants assessed for hypertension ranged from 2074 to 2556 depending on the chemical(s) being analyzed. In unadjusted logistic regressions all 11 PCBs were associated with hypertension. After adjustment for age, gender, race, smoking status, body mass index, exercise, total cholesterol, and family history of coronary heart disease, seven of the 11 PCBs (PCBs 126, 74, 118, 99, 138/158, 170, and 187) were significantly associated with hypertension. The strongest adjusted associations with hypertension were found for dioxin-like PCBs 126 and 118. PCB 126>59.1 pg/g lipid adjusted had an odds ratio of 2.45 (95% CI 1.48-4.04) compared to PCB 12627.5 ng/g lipid adjusted had an odds ratio of 2.30 (95% CI 1.29-4.08) compared to PCB 118or=20 years old in the non-institutionalized US population. We hypothesize that association of seven PCBs with hypertension indicates elevated PCBs are a risk factor for hypertension. What clinicians can do, given the results of this study, is limited unless the appropriate laboratory methods can be made more widely available for testing patients.     

Analysis of factors influencing the comparison of homocysteine values between the Third National Health and Nutrition Examination Survey (NHANES) and NHANES 1999+

Two important changes occurred in the time between the Third National Health and Nutrition Examination Survey (NHANES III) (1991-1994) and the later survey (NHANES 1999+) regarding total homocysteine (tHcy), i.e., a change in matrix from serum to plasma and a change in analytical methods. The goals of this study were to determine the magnitude of potential differences between plasma and serum with regard to tHcy concentrations, and between the two analytical methods used in these surveys. Optimally prepared plasma, serum allowed to clot for 30 and 60 min at room temperature and serum allowed to clot for 30 and 60 min and subjected to four freeze-thaw cycles, prepared from blood samples collected from 30 healthy people, were analyzed by both methods. Serum samples had significantly higher tHcy concentrations than plasma samples, and the difference increased with longer clotting time. Freeze-thaw cycles had little or no effect on the variability or bias in the serum sample results. The tHcy results produced by the two analytical methods were significantly different, but consistent across sample types. On average, the results of the method used in NHANES III were lower by 0.64 micromol/L; however, the relative bias varied with tHcy concentration. The tHcy results determined in surplus serum from NHANES III overestimated tHcy concentrations by approximately 10% compared with optimally prepared plasma. The average method bias was 6% between the two analytical methods. On the basis of changes in matrix and methodology, direct comparison of tHcy results between the two surveys is inappropriate.     

The National Health and Nutrition Examination Survey: Sample Design, 1999-2006

BACKGROUND: Data collection for the National Health and Nutrition Examination Survey (NHANES) comprises three levels: a household screener, an interview, and a physical examination. The primary objective of the screener is to determine whether any household members are eligible for the interview and examination. Eligibility is determined by the preset selection probabilities for the desired demographic subdomains. After selection as an eligible sample person, the interview collects person-level demographic, health, and nutrition information as well as information about the household. The examination includes physical measurements, tests such as eye and dental examinations, and the collection of blood and urine specimens for laboratory testing. OBJECTIVES: This report will first describe the broad design specifications for the 1999-2006 survey including survey objectives, domain and precision specifications, operational requirements, sample design, and estimations procedures. Details of the sample design are divided into two sections. The first section (NHANES 1999-2001 Sample Design) broadly describes the sample design and various design changes during the first three years of the continuous NHANES (1999-2001). The second section (NHANES 2002-2006 Sample Design) describes the final sample design developed and applied for 2002-2006. Weighting and variance estimation procedures are presented in the same manner; however, to correspond to the public data release cycles, the weighting and variance sections are separated into those used for 1999-2002, and those used for 2003-2006. Much of this report is based on survey operations documents and sample design reports prepared by Westat. Documentation of the survey content, procedures, and methods to assess nonsampling errors are reported elsewhere.     

Has Age at Menarche Changed? Results from the National Health and Nutrition Examination Survey (NHANES) 1999–2004

PurposeTo examine self-reported age at menarche in U.S. adults and the associations between age at menarche and race/ethnicity.MethodsData from 1999–2004 National Health and Nutrition Examination Survey (NHANES) for 6788 females 20 years and over were analyzed. Self-reported age at first menses (in years) by birth year groups is reported overall and for Mexican Americans, non-Hispanic whites, and non-Hispanic blacks.ResultsMean age at menarche in the United States declined over time from 13.3 years (95% CI: 13.2–13.5) in the oldest age group, those born prior to 1920, to 12.4 years (95% C.I. 12.2–12.5 years) in the youngest group, born between 1980 and 1984. Declines in age at menarche were observed for all race/ethnicity groups. Non-Hispanic black females had the largest decline in mean age at menarche from 13.6 years (95% CI: 13.1–14.1) in women born prior to 1920, to 12.2 years (95% CI: 11.8–12.6) in the 1980–84 birth cohort. Mean age at menarche among non-Hispanic white females declined from 13.3 years (13.1–13.6) in the pre-1920 birth cohort to 12.5 years (12.3–12.8) in the 1980–84 birth cohort.ConclusionsSignificant declines in the mean age of menarche for U.S. females occurred overall and for all race/ethnic groups examined. Mean age of menarche declined by .9 year overall in women born before 1920 compared to women born in 1980–84; the declines in the mean age at menarche ranged from .7 to 1.4 years depending on the race/ethnicity group.