Vitamin C deficiency and depletion in the United States: the Third National Health and Nutrition Examination Survey, 1988 to 1994

OBJECTIVES: We sought to determine prevalence rates of vitamin C deficiency and depletion in the United States. METHODS: We used data from the Third National Health and Nutrition Examination Survey to assess intake of dietary, supplemental, and serum vitamin C. RESULTS: Mean intakes and serum levels of vitamin C were normal; however, vitamin C deficiency and depletion were common (occurring among 5%-17% and 13%-23% of respondents, respectively). Smokers, those who did not use supplements, and non-Hispanic Black males had elevated risks of vitamin C deficiency, while Mexican Americans had lower risks. CONCLUSIONS: Health professionals should recommend consumption of vegetables and fruits rich in vitamin C and should recommend supplementation for individuals at risk of vitamin C deficiency.     

Serum vitamin C concentrations and diabetes: findings from the Third National Health and Nutrition Examination Survey, 1988-1994.

BACKGROUND: Previous studies suggested that diabetes mellitus may lower serum vitamin C concentrations, but most of these studies used clinic-based populations with established diabetes of varying duration and did not adjust for important covariates. OBJECTIVE: Using a population-based sample and adjusting for important covariates, we asked whether serum vitamin C concentrations in persons with newly diagnosed diabetes differed from those in persons without diabetes. DESIGN: Data were obtained from the third National Health and Nutrition Examination Survey (1988-1994). Serum vitamin C was assayed by using reversed-phase HPLC with multiwavelength detection. Diabetes status (n = 237 persons with diabetes; n = 1803 persons without diabetes) was determined by oral-glucose-tolerance testing of the sample aged 40-74 y. RESULTS: After adjustment for age and sex, mean serum vitamin C concentrations were significantly lower in persons with newly diagnosed diabetes than in those without diabetes. After adjustment for dietary intake of vitamin C and other important covariates, however, mean concentrations did not differ according to diabetes status. CONCLUSION: When assessing serum vitamin C concentrations by diabetes status in the future, researchers should measure and account for all factors that influence serum vitamin C concentrations.     

Homocysteine and blood pressure in the Third National Health and Nutrition Examination Survey, 1988-1994

Studies suggest that homocysteine may elevate blood pressure and increase the risk of hypertension. The association of homocysteine with blood pressure and with the risk of hypertension was investigated using cross-sectional data from the Third National Health and Nutrition Examination Survey (1998-1994). Homocysteine had an independent positive association with blood pressure after adjusting for cardiovascular risk factors. A 1 standard deviation ( approximately 5 micro mol/liter) increase in homocysteine was associated with increases in diastolic and systolic blood pressure of 0.5 and 0.7 mmHg, respectively, in men and of 0.7 and 1.2 mmHg in women. Similarly, higher levels of homocysteine were associated with an increased risk of hypertension. In a comparison of the highest and lowest quintiles of homocysteine, women had a threefold increase in the risk of hypertension (95% confidence interval (CI): 1.7, 5.4), and men had a twofold increase (95% CI: 0.7, 5.1). In light of the homocysteine-blood pressure association, the association of homocysteine with prevalent cardiovascular disease was examined with and without adjusting for blood pressure. The results support a mediating role for blood pressure in women and suggest that the full effect of homocysteine on cardiovascular risk may be underestimated when blood pressure is adjusted.     

Serum retinol distributions in residents of the United States: third National Health and Nutrition Examination Survey, 1988-1994

BACKGROUND: Inadequate vitamin A status has been a potential nutritional problem for some segments of the US population, particularly children and the poor. OBJECTIVE: We evaluated serum retinol concentration by using population-representative data from 16058 participants aged 4 to >/=90 y in the third National Health and Nutrition Examination Survey, 1988-1994. DESIGN: We used multivariate regression to examine the simultaneous associations of sociodemographic, biologic, and behavioral factors with serum retinol concentration. RESULTS: In children, serum retinol concentrations were greater with greater age, body mass index, serum lipids, and the use of supplements containing vitamin A. In adults, male sex, serum lipids, alcohol consumption, and age were positively associated with serum retinol concentration in most racial/ethnic strata. Household income was not associated with serum retinol concentration in children; associations were inconsistent in adults. The prevalence of serum retinol <0.70 micromol/L was very low in all strata; the prevalence of serum retinol <1.05 micromol/L was 16.7-33.9% in children aged 4-8 y and 3.6-14.2% in children aged 9-13 y, depending on sex and racial/ethnic group. The prevalence of serum retinol<1.05 micromol/L was higher in non-Hispanic black and Mexican American children than in non-Hispanic white children; these differences remained significant (P < 0.0001) after covariates were controlled for. Among adults, nonwhite women were significantly (P < 0.0001) more likely than white women to have serum retinol <1.05 micromol/L after covariates were controlled for. CONCLUSIONS: Clinically low serum retinol concentration is uncommon in US residents aged > or = 4 y, although racial/ethnic and socioeconomic differences in serum retinol concentration still exist.     

Prevalence in the United States of selected candidate gene variants: Third National Health and Nutrition Examination Survey, 1991-1994

Population-based allele frequencies and genotype prevalence are important for measuring the contribution of genetic variation to human disease susceptibility, progression, and outcomes. Population-based prevalence estimates also provide the basis for epidemiologic studies of gene-disease associations, for estimating population attributable risk, and for informing health policy and clinical and public health practice. However, such prevalence estimates for genotypes important to public health remain undetermined for the major racial and ethnic groups in the US population. DNA was collected from 7,159 participants aged 12 years or older in Phase 2 (1991-1994) of the Third National Health and Nutrition Examination Survey (NHANES III). Certain age and minority groups were oversampled in this weighted, population-based US survey. Estimates of allele frequency and genotype prevalence for 90 variants in 50 genes chosen for their potential public health significance were calculated by age, sex, and race/ethnicity among non-Hispanic whites, non-Hispanic blacks, and Mexican Americans. These nationally representative data on allele frequency and genotype prevalence provide a valuable resource for future epidemiologic studies in public health in the United States.     

Intraindividual variation in serum retinol concentrations among participants in the third National Health and Nutrition Examination Survey, 1988-1994

BACKGROUND: The biological variability in serum retinol concentrations has never been examined in a large sample, and its effect on population distribution estimates and the clinical assessment of vitamin A status is unknown. OBJECTIVE: We evaluated the biological CV of serum retinol and examined the effect of the CV on both population distribution estimates and clinical assessments of vitamin A status by using data from the third National Health and Nutrition Examination Survey, 1988-1994. DESIGN: We described the biological CV [(SD/x) x 100] and examined associations between the CV and other factors via multivariate analysis of variance and linear regression. We used linear regression to predict the mean retinol concentration from a single concentration and established 95% CIs for each participant. We estimated the adjusted prevalence of inadequate vitamin A status (retinol < 1.05 micromol/L) on the basis of the CIs. We estimated an uncertainty range for serum retinol concentrations for which the CIs included the established cutoff. RESULTS: The mean biological CV across all strata was 6.45%. The biological CV varied significantly between racial-ethnic groups (P < 0.05). Prevalence estimates of inadequate serum retinol concentrations were reduced after adjustment for the total variation, with an adjusted overall prevalence of 0.62% compared with an unadjusted prevalence of 2.63%. CONCLUSIONS: The actual population prevalence of inadequate vitamin A status may be 75% lower than the estimates previously reported. Confirmation of vitamin A status may be needed for persons in the United States with observed serum retinol concentrations near the recognized cutoff.     

Volatile organic compounds and pulmonary function in the Third National Health and Nutrition Examination Survey, 1988-1994

BACKGROUND: Volatile organic compounds (VOCs) are present in much higher concentrations indoors, where people spend most of their time, than outdoors and may have adverse health effects. VOCs have been associated with respiratory symptoms, but few studies address objective respiratory end points such as pulmonary function. Blood levels of VOCs may be more indicative of personal exposures than are air concentrations; no studies have addressed their relationship with respiratory outcomes. OBJECTIVE: We examined whether concentrations of 11 VOCs that were commonly identified in blood from a sample of the U.S. population were associated with pulmonary function. METHODS: We used data from 953 adult participants (20-59 years of age) in the Third National Health and Nutrition Examination Survey (1988-1994) who had VOC blood measures as well as pulmonary function measures. Linear regression models were used to evaluate the relationship between 11 VOCs and measures of pulmonary function. RESULTS: After adjustment for smoking, only 1,4-dichlorobenzene (1,4-DCB) was associated with reduced pulmonary function. Participants in the highest decile of 1,4-DCB concentration had decrements of -153 mL [95% confidence interval (CI) , -297 to -8] in forced expiratory volume in 1 sec and -346 mL/sec (95% CI, -667 to -24) in maximum mid-expiratory flow rate, compared with participants in the lowest decile. CONCLUSIONS: Exposure to 1,4-DCB, a VOC related to the use of air fresheners, toilet bowl deodorants, and mothballs, at levels found in the U.S. general population, may result in reduced pulmonary function. This common exposure may have long-term adverse effects on respiratory health.     

Demographic,health, lifestyle,and blood vitamin determinants of serum total homocysteine concentrations in the third National Health and Nutrition Examination Survey, 1988-1994

BACKGROUND: Elevated serum total homocysteine (tHcy) is an independent risk factor for vascular diseases. OBJECTIVE: Associations between serum tHcy and demographics, health and lifestyle factors, and blood vitamin concentrations were investigated. DESIGN: Data from the third National Health and Nutrition Examination Survey, 1988-1994 were used to examine associations in men (n = 2965) and women (n = 3580) between tHcy and age, sex, race-ethnicity, body mass index, systolic and diastolic blood pressures, alcohol consumption, supplement use, red blood cell (RBC) folate, and serum creatinine, folate, vitamin B-12, and cotinine (a measure of cigarette smoking). RESULTS: The unadjusted mean tHcy was 21.5% ( approximately 1.9 micro mol/L) higher in men than in women, 11.8% ( approximately 1.1 micro mol/L) higher in non-Hispanic whites than in Mexican Americans, 42% ( approximately 3.7 micro mol/L) higher in persons aged > or = 70 y than in persons aged < 30 y, and 10.9% ( approximately 1.0 micro mol/L) higher in supplement nonusers than in supplement users. The tHcy concentration was negatively associated with serum folate (P < 0.0001 for trend), RBC folate (P < 0.0001 for trend), and serum vitamin B-12 (P < 0.0036 for trend) and was positively associated with alcohol consumption (P < 0.0001 for trend), serum cotinine (P < 0.0001 for trend), and systolic blood pressure (P < 0.0001 for trend). Consumption of hard liquor (but not of beer or wine) was positively associated with tHcy concentration (P < 0.0001 for trend). CONCLUSIONS: In this population-based study, the significant predictors of tHcy concentration were sex, age, race-ethnicity, serum creatinine, systolic blood pressure, body mass index, hard-liquor consumption, smoking, supplement use, serum folate, RBC folate, and serum vitamin B-12.     

Helicobacter pylori and overweight status in the United States: data from the Third National Health and Nutrition Examination Survey

Obesity is an important public health problem in the United States. Because of its potential effects on gastric leptin homeostasis, Helicobacter pylori may play a role in regulating body weight. The authors' aim in this study was to examine the association between H. pylori colonization and overweight status. Nonpregnant participants in the Third National Health and Nutrition Examination Survey (1988-1994) aged > or = 20 years who had had H. pylori testing performed and body mass index (weight (kg)/height (m2)) measured were studied. Overweight was defined as a body mass index greater than or equal to 25. On the basis of serologic results, the participants were categorized into three H. pylori status groups: H. pylori-positive and cytotoxin-associated gene A (cagA)-positive (H. pylori+ cagA+), H. pylori-positive and cagA-negative (H. pylori+ cagA-), and H. pylori-negative (H. pylori-). Of the 7,003 subjects with complete body mass index and H. pylori data, 2,634 (weighted percentage, 22.9%) were H. pylori+ cagA+, 1,385 (15.1%) were H. pylori+ cagA-, and 2,984 (62.0%) were H. pylori-. The adjusted odds of being overweight were 1.17 (95% confidence interval: 0.98, 1.39; p = 0.075) for the H. pylori+ cagA+ group and 0.99 (95% confidence interval: 0.80, 1.22; p = 0.92) for the H. pylori+ cagA- group in comparison with H. pylori- subjects. Serum leptin levels did not differ significantly between the three H. pylori groups. In this US population-based study, there was no significant association between H. pylori colonization, cagA+ strains of H. pylori, and being overweight.     

Dietary intakes and serum nutrients differ between adults from food-insufficient and food-sufficient families: Third National Health and Nutrition Examination Survey, 1988-1994

Approximately 10.2 million persons in the United States sometimes or often do not have enough food to eat, a condition known as food insufficiency. Using cross-sectional data from the Third National Health and Nutrition Examination Survey (NHANES III), we examined whether dietary intakes and serum nutrients differed between adults from food-insufficient families (FIF) and adults from food-sufficient families (FSF). Results from analyses, stratified by age group and adjusted for family income and other important covariates, revealed several significant findings (P < 0.05). Compared with their food-sufficient counterparts, younger adults (aged 20-59 y) from FIF had lower intakes of calcium and were more likely to have calcium and vitamin E intakes below 50% of the recommended amounts on a given day. Younger adults from FIF also reported lower 1-mo frequency of consumption of milk/milk products, fruits/fruit juices and vegetables. In addition, younger adults from FIF had lower serum concentrations of total cholesterol, vitamin A and three carotenoids (alpha-carotene, beta-cryptoxanthin and lutein/zeaxanthin). Older adults (aged > or =60 y) from FIF had lower intakes of energy, vitamin B-6, magnesium, iron and zinc and were more likely to have iron and zinc intakes below 50% of the recommended amount on a given day. Older adults from FIF also had lower serum concentrations of high-density lipoprotein cholesterol, albumin, vitamin A, beta-cryptoxanthin and vitamin E. Both younger and older adults from FIF were more likely to have very low serum albumin (<35 g/L) than were adults from FSF. Our findings show that adults from FIF have diets that may compromise their health.     

Bone density-related predictors of blood lead level among peri- and postmenopausal women in the United States: The Third National Health and Nutrition Examination Survey, 1988-1994

Because of the long half-life of lead stored in bone (years), skeletal lead stores may be a source of endogenous lead exposure during periods of increased bone demineralization, such as menopause. To test the hypothesis that postmenopausal bone resorption increases blood lead levels, the authors examined cross-sectional associations of bone density-related factors with blood lead levels among women aged 40-59 years from the Third National Health and Nutrition Examination Survey (1988-1994). Factors related to bone turnover were significant predictors of blood lead level. Bone mineral density was significantly inversely related to blood lead levels in log-linear multivariate models that adjusted for age, race/ethnicity, smoking, education, household income, alcohol use, and residence (urban/rural). With menopausal status added to the model, naturally and surgically menopausal women had adjusted median blood lead levels that were 25% and 30% higher, respectively, than those of premenopausal women (2.0 microg/dl). Current use of hormone replacement therapy was associated with significantly lower adjusted median blood lead levels (1.8 microg/dl) than past use (2.6 microg/dl) and never use (2.2 microg/dl). Lead stored in bone may significantly increase blood lead levels in perimenopausal women because of postmenopausal bone mineral resorption. Attention to factors that prevent bone loss may lessen or prevent this endogenous lead exposure.     

Trends in serum folate, RBC folate, and circulating total homocysteine concentrations in the United States: analysis of data from National Health and Nutrition Examination Surveys, 1988-1994, 1999-2000, and 2001-2002

Folate intakes increased dramatically after folic acid fortification. We investigated the changes in serum folate, RBC folate, and total homocysteine (tHcy) concentrations utilizing data from National Health and Nutrition Examination Surveys (NHANES) 1988-2002. NHANES 1988-2002 were based on a stratified, multistage, probability sampling design conducted among civilian U.S. residents. The current study included 17,144, 17,213, and 11,415 measurements for serum folate, RBC folate, and tHcy, respectively. Overall, geometric mean serum folate concentrations were 149.6 and 129.8% higher in 1999-2000 and 2001-2002, respectively, than in 1988-1994 (P < 0.0001). Sex-, age-, and race-ethnicity-adjusted serum folate was significantly lower in 2001-2002 than in 1999-2000 (10.4%, P < 0.0002). The prevalence of low serum folate decreased from 18.4% in 1988-1994 to 0.8% in 1999-2000 and to 0.2% in 2001-2002 (P < 0.0001). RBC folate increased from 391 nmol/L in 1988-1994 to 618 nmol/L in 1999-2000, and to 611 nmol/L in 2001-2002. Consequently, the prevalence of low RBC folate decreased from 45.8% in 1988-1994 to 7.3% in 1999-2000 and to 7.1% in 2001-2002 (P < 0.0001). Although, RBC folate status improved after folic acid fortification in all race-ethnicities, the prevalence of low RBC folate ( approximately 20.5%) continues to be high in non-Hispanic blacks. Age-, sex-, and race-ethnicity-adjusted tHcy declined from 9.5 micromol/L in 1988-1994 to 7.6 mumol/L in 1999-2000 and to 7.9 micromol/L in 2001-2002. Although folic acid fortification contributed to significant improvement in folate status, serum folate concentrations have declined recently. This may be attributable to lower folic acid intakes.     

Stature and pubertal stage assessment in American boys: the 1988-1994 Third National Health and Nutrition Examination Survey.

PURPOSE: To describe current stature and pubertal development in North American boys, and to compare these measures with measures observed approximately 30 years ago. METHODS: We analyzed data (i.e., height, weight, and Tanner Stage) from the Third National Health and Nutrition Examination Survey (NHANES III), conducted between 1988-1994, and compared it to the National Health Examination Survey, Cycles II and III (HES II/III), conducted from 1963-1965 and 1966-1970. The surveys included physical examination and questionnaire components, employed cross-sectional designs, and are nationally representative. We used logistic regression to calculate median age at onset of pubertal stages. RESULTS: NHANES III included 2481 boys aged 8 to 18 years. HES II comprised 3010 boys aged 8-11 years and HES III comprised 3514 boys aged 12-17 years. The mean heights of the oldest boys in both surveys did not differ significantly; however, at younger ages, boys in the more recent survey were taller (average height difference among those aged 8-14 years was 2.0 cm). Boys in NHANES III were also heavier and had higher body mass index than those in HES II/III. The median estimated ages of onset of pubertal stages in NHANES III were 9.9, 12.2, 13.6, and 15.8 years for genital stages 2-5, respectively, and 11.9, 12.6, 13.6, and 15.7 years for pubic hair stages 2-5, respectively. For some stages, the median estimated age of onset of puberty was earlier among boys in NHANES III than among those in HES III. CONCLUSIONS: Differences in mean height at young ages, but not at older ages, suggest that the rate of growth among boys in NHANES III was faster than that of boys in the earlier surveys. This finding, coupled with the finding of earlier ages of onset of some pubertal stages, suggests that boys of this generation may be maturing more rapidly than did boys in the past.     

Modifiable and nonmodifiable factors associated with osteoporosis in postmenopausal women: results from the Third National Health and Nutrition Examination Survey, 1988-1994

We wished to study the relationship between modifiable and nonmodifiable factors that were correlated with osteoporosis using a national sample of women aged 50 years and older who have never been on hormone replacement therapy (HRT). We used a cross-sectional study design with a nationally representative sample with a detailed clinical examination and a home interview. Between 1988 and 1994, 1953 postmenopausal women who had never been on HRT, aged 50 years and older, were examined as part of the Third National Health and Nutrition Examination Survey (NHANES III). Mexican Americans and non-Hispanic blacks were oversampled to produce reliable estimates for these groups. Bone density measurements of four proximal femur sites were assessed by using x-ray absorptiometry (DEXA). A DEXA measurement at any single femur site indicated osteoporosis if it was >2.5 standard deviations (SD) below the reference mean of 20--29-year-old women. The study demonstrated that numerous factors, both modifiable and nonmodifiable, were significantly related to the prevalence of osteoporosis. The modifiable factors identified were participation in physical activity (three to five times per week) and body mass index (BMI). Nonmodifiable factors included age, race, and mother's history. With the aging population, osteoporosis is a growing concern for the medical community. It is suggested that educational strategies are needed to increase awareness of factors that contribute to maintaining bone health among postmenopausal women. Emphasis may be placed on maintaining regular physical activity.     

Acculturation in the United States is associated with lower serum carotenoid levels: Third National Health and Nutrition Examination Survey

This study examined the association of acculturation in the United States and serum carotenoid levels. The design was a cross-sectional, nationally representative survey of 16,539 participants, 17 years of age and older, from the Third National Health and Nutrition Examination Survey (NHANES III). The main outcome measures were serum levels of alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein/zeaxanthin, lycopene, and total carotenoids. Multivariate linear regression was used to model the association of serum carotenoids and country of birth, language of interview, and years in the United States. Adjustments were made for age, sex, years of education, race/ethnicity, body mass index, alcohol use, physical activity, serum cotinine, serum cholesterol, and vitamin/mineral usage. Individuals born in the United States who speak English had the lowest levels of carotenoids, and individuals born in Mexico had the highest levels of carotenoids, with the exception of lycopene. Years of residence in the United States was associated with lower alpha-carotene (4.18 vs 1.51), beta-carotene (20.21 vs 14.87), beta-cryptoxanthin (12.51 vs 8.95), lutein/zeaxanthin (25.15 vs 18.03), and total carotenoids (88.79 vs 75.44). Years residence in the United States was positively associated with higher lycopene levels (26.69 vs 32.03). Acculturation in the United States was associated with lower fruit and vegetable intake, as measured by serum carotenoid levels.     

Associations of serum C-reactive protein with fasting insulin, glucose, and glycosylated hemoglobin: the Third National Health and Nutrition Examination Survey, 1988-1994.

This study investigated the associations between serum C-reactive protein and fasting blood levels of insulin, glucose, and hemoglobin A1c (HbA1c). Data from the Third National Health and Nutrition Examination Survey (1998-1994) were used. Study subjects included 2,466 men and 2,876 women who were > or = 17 years and nondiabetics with an overnight fast for blood draw. C-reactive protein was categorized into low (<0.3 mg/dl), moderate (0.3-0.9 mg/dl), and high (> or = 1.0 mg/dl) levels. Mean levels of insulin, glucose, and HbA1c were compared across C-reactive protein levels after adjustment for age, ethnicity, education, poverty index, cigarette smoking, alcohol use, and leisure time physical activity. For men with low (n = 1,818), moderate (n = 493), and high (n = 155) C-reactive protein, the adjusted means of insulin were 9.4, 11.7, and 10.5 microunits/ml (p < 0.01); glucose, 99.8, 101.6, and 100.6 mg/dl (p > 0.05); and HbA1c, 5.4%, 5.5%, and 5.5% (p < 0.05). For women with low (n = 1,816), moderate (n = 776), and high (n = 282) C-reactive protein, the adjusted means of insulin were 8.7, 11.2, and 13.7 microunits/ml (p < 0.01); glucose, 95.3, 97.9, and 105.2 mg/dl (p < 0.01); and HbA1c, 5.3%, 5.4%, and 5.6% (p < 0.01). In conclusion, elevated C-reactive protein was associated with higher insulin and HbA1c among men and women and with higher glucose levels among women only. These results suggest a possible role of inflammation in insulin resistance and glucose intolerance.     

Serum cholesterol concentrations are associated with visuomotor speed in men: findings from the third National Health and Nutrition Examination Survey, 1988-1994

BACKGROUND: Current international recommendations advise aggressive treatment of relative hypercholesterolemia despite an incomplete understanding of any neurobehavioral effects of low or lowered serum cholesterol. OBJECTIVE: The objective was to examine the relation between serum cholesterol concentrations and performance in immediate memory, visuomotor speed, and coding speed tests. DESIGN: The participants were 4110 adults aged 20-59 y who completed a set of neurobehavioral tests and had blood specimens collected as a part of the third National Health and Nutrition Examination Survey, 1988-1994. RESULTS: After adjustment for sociodemographic variables, serum trace elements and vitamins, dietary energy intake, and risk factors for cardiovascular disease, we found inverse linear associations of serum total cholesterol and non-HDL cholesterol with visuomotor speed in men. The least-squares mean (+/- SE) visuomotor speeds were 231.6 +/- 2.6, 224.0 +/- 2.2, and 218.9 +/- 2.5 ms, respectively, for men with serum total cholesterol concentrations below the 25th, between the 25th and the 75th, and at or above the 75th percentile (P for trend < 0.001) and were 231.7 +/- 2.7, 225.8 +/- 2.4, and 214.1 +/- 2.3 ms, respectively, for men with a non-HDL-cholesterol concentration below the 25th, between the 25th and the 75th, and at or above the 75th percentile (P for trend < 0.001). No significant associations were observed between memory or coding speed and the selected serum cholesterol measures in men, and the scores of the 3 neurobehavioral tests were unrelated to serum cholesterol in women. CONCLUSION: Low serum total cholesterol and non-HDL cholesterol are associated with slow visuomotor speed in young and middle-aged men.     

Hepatitis A virus infection in the United States: serologic results from the Third National Health and Nutrition Examination Survey

To determine the prevalence of hepatitis A virus (HAV) infection in the general U.S. population, sera from participants in the Third National Health and Nutrition Examination Survey (NHANES III) conducted in 1988–1994 were tested for antibody to HAV (anti-HAV). Among 21,260 participants aged ≥6 years tested, the overall prevalence of infection was 31.3%, and increased markedly with age. The age-adjusted prevalence was significantly higher among foreign- compared to U.S.-born participants, and was highest among Mexican-Americans and lowest among non-Hispanic whites. Among U.S.-born children, only Mexican-American ethnicity and income below the poverty level were associated with HAV infection in a multivariate model. During this period before hepatitis A vaccination, age, ethnicity and birthplace were the most important determinants of HAV infection in the United States.     

Serum alpha-tocopherol status in the United States population: findings from the Third National Health and Nutrition Examination Survey.

Despite the role vitamin E may have in protecting against various chronic conditions, little is known about vitamin E status in the US population. Using data from the Third National Health and Nutrition Examination Survey (1988-1994), the authors examined the distribution and correlates of serum alpha-tocopherol among 16,295 US adults aged 18 or more years. The mean concentration of alpha-tocopherol was 26.8 micromol/liter (geometric mean, 25.0 micromol/liter).The 25th, 50th, and 75th percentiles were 19.6, 24.1, and 30.4 micromol/liter, respectively.The mean alpha-tocopherol/cholesterol ratio was 5.1 (geometric mean, 4.9); the 25th, 50th, and 75th percentiles were 4.1, 4.7, and 5.5 (10(-3)), respectively. About 27% of the US population had a low alpha-tocopherol concentration (<20 micromol/liter). After age standardization, 29% of the men, 28% of the women, 26% of the Whites (men, 27%, and women, 26%), 41% of the African Americans (men, 42%, and women, 40%), 28% of the Mexican Americans (men, 29%, and women, 27%), and 32% of the other participants (men, 36%, and women, 29%) had this low concentration. For all participants, age, educational attainment, serum cholesterol, and several serum vitamins and carotenoids were directly related to and high density lipoprotein cholesterol was inversely related to serum alpha-tocopherol concentration in multiple linear regression analysis. Men had a higher concentration than did women, and African Americans had the lowest concentration of any racial or ethnic group. These results show that important proportions of US adults have a low serum alpha-tocopherol concentration, which may increase their risk for chronic diseases in which low dietary intake or blood concentration of alpha-tocopherol have been implicated.     

Blood lead levels and sexual maturation in U.S. girls: the Third National Health and Nutrition Examination Survey, 1988-1994

Using data from the Third National Health and Nutrition Examination Survey, we assessed measures of puberty in U.S. girls in relation to blood lead levels to determine whether sexual maturation may be affected by current environmental lead exposure. The study sample included 1,706 girls 8-16 years old with pubic hair and breast development information; 1,235 girls 10-16 years old supplied information on menarche. Blood lead concentrations (range = 0.7-21.7 micro g/dL) were categorized into three levels: 0.7-2.0, 2.1-4.9, and 5.0-21.7 micro g/dL. Sexual maturation markers included self-reported attainment of menarche and physician determined Tanner stage 2 pubic hair and breast development. Girls who had not reached menarche or stage 2 pubic hair had higher blood lead levels than did girls who had. For example, among girls in the three levels of blood lead described above, the unweighted percentages of 10-year-olds who had attained Tanner stage 2 pubic hair were 60.0, 51.2, and 44.4%, respectively, and for girls 12 years old who reported reaching menarche, the values were 68.0, 44.3, and 38.5%, respectively. The negative relation of blood lead levels with attainment of menarche or stage 2 pubic hair remained significant in logistic regression even after adjustment for race/ethnicity, age, family size, residence in metropolitan area, poverty income ratio, and body mass index. In conclusion, higher blood lead levels were significantly associated with delayed attainment of menarche and pubic hair among U.S. girls, but not with breast development.