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Christopher T Sempos,
Ramón A Durazo-Arvizu,
Bess Dawson-Hughes,
Elizabeth A Yetley,
Anne C Looker, Rosemary L Schleicher,
Guichan Cao,
Vicki Burt,
Holly Kramer,
Regan L Bailey,
Johanna T Dwyer,
Xinli Zhang,
Jaime Gahche,
Paul R Thomas,
Paul M Coates,
Mary Frances Picciano
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ABSTRACT: Context:A reverse J-shaped association between serum 25-hydroxyvitamin D [25(OH)D] concentration and all-cause mortality was suggested in a nine-year follow-up (1991-2000) analysis of the Third National Health and Nutrition Examination Survey (NHANES III, 1988-1994).Objectives:Repeat the analyses with six years additional follow-up to evaluate if the association persists through 15-years of follow-up.Design, Setting, and Participants:15,099 participants ages 20+ years with 3,784 deaths.Main Outcome Measure:Relative risk (RR) of death from all-causes was adjusted for age, sex, race-ethnicity and season using two Poisson regression approaches - traditional categorical and cubic splines. Results were given for nine 25(OH)D (nmol/L) levels: < 20, 20-29, 30-39, 40-49, 50-59, 60-74, 75-99 (reference), 100-119, and ≥120.Results:The reverse J-shaped association became stronger with longer follow-up and was not affected by excluding deaths within the first 3-years of follow-up. Similar results were found from both statistical approaches for levels <20 through 119 nmol/L. Adjusted RR (95% CI) estimates for all levels < 60 nmol/L were significantly >1 compared to the reference group. The nadir of risk was 81 nmol/L (95% CI, 73-90 nmol/L). For 25(OH)D ≥120 nmol/L, results [RR, 95% CI] were slightly different using traditional categorical [1.5, 1.02-2.3] and cubic splines approaches [1.2, 0.9-1.4]. The association appeared in men, women, adults ages 20-64 and non-Hispanic whites but was weaker in older adults. The study was too small to evaluate the association in non-Hispanic black and Mexican-American adults.Conclusions:A reverse J-shaped association between serum 25(OH)D and all-cause mortality appears to be real. It is uncertain if the association is causal.
The Journal of clinical endocrinology and metabolism 05/2013; · 6.50 Impact Factor
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ABSTRACT: BACKGROUND: During 1998, weather conditions in the United States favored the growth of Aspergillus species leading to widespread contamination of Midwestern and Southern corn with hepatotoxic and hepatocarcinogenic aflatoxins. We designed to provide the first national prevalence estimate of aflatoxin exposure using the National Health and Nutrition Examination Survey (NHANES), a representative cross-sectional survey of the noninstitutionalized civilian population of the US. METHODS: Isotope dilution liquid chromatography-tandem mass spectrometry was used to quantitate serum concentrations of aflatoxin B1-lysine in a one-third random subset of participants from NHANES 1999-2000. RESULTS: About 1% of the U.S. population had detectable levels (≥0.02 μg/l) of aflatoxin B1-lysine. Of those with detectable levels, the geometric mean (95% confidence interval) was 0.038 (0.024-0.060) μg/l (equivalent to 0.842 (0.530-1.34) pg/mg albumin). The highest value was 0.2 μg/l (4.43 pg/mg albumin). Based on liver function biomarkers, there was no evidence of increased liver dysfunction in these persons. CONCLUSIONS: During a time when exposure to aflatoxins in food products might have been expected to be increased, we identified few exposed persons. Although none of the subgroup analyses provided reliable estimates due to high relative standard errors, they suggested that additional targeted surveillance may be warranted.
Clinica chimica acta; international journal of clinical chemistry 04/2013; · 2.54 Impact Factor
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ABSTRACT: The collection of articles in this supplement issue provides insight into the association of various covariates with concentrations of biochemical indicators of diet and nutrition (biomarkers), beyond age, race, and sex, using linear regression. We studied 10 specific sociodemographic and lifestyle covariates in combination with 29 biomarkers from NHANES 2003-2006 for persons aged ≥20 y. The covariates were organized into 2 sets or "chunks": sociodemographic (age, sex, race-ethnicity, education, and income) and lifestyle (dietary supplement use, smoking, alcohol consumption, BMI, and physical activity) and fit in hierarchical fashion by using each category or set of related variables to determine how covariates, jointly, are related to biomarker concentrations. In contrast to many regression modeling applications, all variables were retained in a full regression model regardless of significance to preserve the interpretation of the statistical properties of β coefficients, P values, and CIs and to keep the interpretation consistent across a set of biomarkers. The variables were preselected before data analysis, and the data analysis plan was designed at the outset to minimize the reporting of false-positive findings by limiting the amount of preliminary hypothesis testing. Although we generally found that demographic differences seen in biomarkers were over- or underestimated when ignoring other key covariates, the demographic differences generally remained significant after adjusting for sociodemographic and lifestyle variables. These articles are intended to provide a foundation to researchers to help them generate hypotheses for future studies or data analyses and/or develop predictive regression models using the wealth of NHANES data.
Journal of Nutrition 04/2013; · 3.92 Impact Factor
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ABSTRACT: The physiologic status of an individual may influence biomarkers of nutritional status. To help researchers with planning studies and interpreting data, we assessed the associations between common physiologic variables (fasting, inflammation, renal function, and pregnancy) and 29 biomarkers of diet and nutrition measured in blood or urine in a representative sample of the adult U.S. population (aged ≥20 y; pregnancy variable and iron indicators limited to women aged 20-49 y) participating in NHANES 2003-2006. We compared simple linear regression (model 1) with multiple linear regression [model 2, controlling for age, sex, race-ethnicity, smoking, supplement use, and the physiologic factors (and urine creatinine for urine biomarkers)] and report significant findings from model 2. Not being fasted was positively associated with most water-soluble vitamins (WSVs) and related metabolites (RMs). Some WSV, fat-soluble vitamin (FSV) and micronutrient (MN), and phytoestrogen concentrations were lower in the presence of inflammation (C-reactive protein ≥5 mg/L), whereas fatty acids and most iron indicators were higher. Most WSVs and RMs were higher when renal function was impaired [estimated glomerular filtration rate <60 mL/(min ⋅ 1.73 m(2))]. Most WSV, FSV and MN, and fatty acid concentrations were higher in pregnant compared with nonpregnant women, but vitamins A and B-12 and most iron indicators were lower. The estimated changes in biomarker concentrations with different physiologic status were mostly small to moderate (≤25%) and generally similar between models; renal function, however, showed several large differences for WSV and RM concentrations. This descriptive analysis of associations between physiologic variables and a large number of nutritional biomarkers showed that controlling for demographic variables, smoking, and supplement use generally did not change the interpretation of bivariate results. The analysis serves as a useful basis for more complex future research.
Journal of Nutrition 04/2013; · 3.92 Impact Factor
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ABSTRACT: The CDC's National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population (Nutrition Report) is a serial publication that provides ongoing assessment of the population's nutritional status. The Nutrition Report presents data on blood and urine biomarker concentrations (selected water- and fat-soluble vitamins and nutrients, trace elements, dietary bioactive compounds) from a representative sample of the population participating in the NHANES. The Second Nutrition Report (released in 2012) contains reference information (means and percentiles) for 58 biomarkers measured during all or part of 2003-2006, stratified by age, sex, and race-ethnicity. Where available, we presented cutoff-based prevalence data during 2003-2006 and data on changes in biomarker concentrations or prevalence since 1999. Blood vitamin concentrations were generally higher in older (≥60 y) than in younger (20-39 y) adults and lower in Mexican Americans and non-Hispanic blacks than in non-Hispanic whites. Nearly 80% of Americans (aged ≥6 y) were not at risk of deficiencies in any of the 7 vitamins studied (vitamins A, B-6, B-12, C, D, and E and folate). Deficiency rates varied by age, sex, and race-ethnicity. Approximately 90% of women (aged 12-49 y) were not at risk of iron deficiency, but only 68% were not at risk of deficiencies in iron and all 7 vitamins. Young women (20-39 y) had median urine iodine concentrations bordering on insufficiency. First-time data are presented on plasma concentrations of 24 saturated and mono- and polyunsaturated fatty acids. Tabulation and graphical presentation of NHANES data in the Second Nutrition Report benefits those organizations involved in developing and evaluating nutrition policy.
Journal of Nutrition 04/2013; · 3.92 Impact Factor
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ABSTRACT: Sociodemographic and lifestyle factors exert important influences on nutritional status; however, information on their association with biomarkers of fat-soluble nutrients is limited, particularly in a representative sample of adults. Serum or plasma concentrations of vitamin A, vitamin E, carotenes, xanthophylls, 25-hydroxyvitamin D [25(OH)D], SFAs, MUFAs, PUFAs, and total fatty acids (tFAs) were measured in adults (aged ≥20 y) during all or part of NHANES 2003-2006. Simple and multiple linear regression models were used to assess 5 sociodemographic variables (age, sex, race-ethnicity, education, and income) and 5 lifestyle behaviors (smoking, alcohol consumption, BMI, physical activity, and supplement use) and their relation to biomarker concentrations. Adjustment for total serum cholesterol and lipid-altering drug use was added to the full regression model. Adjustment for latitude and season was added to the full model for 25(OH)D. Based on simple linear regression, race-ethnicity, BMI, and supplement use were significantly related to all fat-soluble biomarkers. Sociodemographic variables as a group explained 5-17% of biomarker variability, whereas together, sociodemographic and lifestyle variables explained 22-23% [25(OH)D, vitamin E, xanthophylls], 17% (vitamin A), 15% (MUFAs), 10-11% (SFAs, carotenes, tFAs), and 6% (PUFAs) of biomarker variability. Although lipid adjustment explained additional variability for all biomarkers except for 25(OH)D, it appeared to be largely independent of sociodemographic and lifestyle variables. After adjusting for sociodemographic, lifestyle, and lipid-related variables, major differences in biomarkers were associated with race-ethnicity (from -44 to 57%), smoking (up to -25%), supplement use (up to 21%), and BMI (up to -15%). Latitude and season attenuated some race-ethnicity differences. Of the sociodemographic and lifestyle variables examined, with or without lipid adjustment, most fat-soluble nutrient biomarkers were significantly associated with race-ethnicity.
Journal of Nutrition 04/2013; · 3.92 Impact Factor
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ABSTRACT: Biochemical indicators of water-soluble vitamin (WSV) status were measured in a nationally representative sample of the U.S. population in NHANES 2003-2006. To examine whether demographic differentials in nutritional status were related to and confounded by certain variables, we assessed the association of sociodemographic (age, sex, race-ethnicity, education, income) and lifestyle (dietary supplement use, smoking, alcohol consumption, BMI, physical activity) variables with biomarkers of WSV status in adults (aged ≥20 y): serum and RBC folate, serum pyridoxal-5'-phosphate (PLP), serum 4-pyridoxic acid, serum total cobalamin (vitamin B-12), plasma total homocysteine (tHcy), plasma methylmalonic acid (MMA), and serum ascorbic acid. Age (except for PLP) and smoking (except for MMA) were generally the strongest significant correlates of these biomarkers (|r| ≤ 0.43) and together with supplement use explained more of the variability compared with the other covariates in bivariate analysis. In multiple regression models, sociodemographic and lifestyle variables together explained from 7 (vitamin B-12) to 29% (tHcy) of the biomarker variability. We observed significant associations for most biomarkers (≥6 of 8) with age, sex, race-ethnicity, supplement use, smoking, and BMI and for some biomarkers with PIR (5 of 8), education (1 of 8), alcohol consumption (4 of 8), and physical activity (5 of 8). We noted large estimated percentage changes in biomarker concentrations between race-ethnic groups (from -24 to 20%), between supplement users and nonusers (from -12 to 104%), and between smokers and nonsmokers (from -28 to 8%). In summary, age, sex, and race-ethnic differentials in biomarker concentrations remained significant after adjusting for sociodemographic and lifestyle variables. Supplement use and smoking were important correlates of biomarkers of WSV status.
Journal of Nutrition 04/2013; · 3.92 Impact Factor
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ABSTRACT: The National Health and Nutrition Examination Survey (NHANES) provides the most comprehensive assessment of the health and nutrition status of the US population. Up-to-date reference intervals on biomarkers and dietary intake inform the scientific and public health policy communities on current status and trends over time.The main purpose of dietary assessment methods such as the food-frequency questionnaire, food record (or diary), and 24-hr dietary recall is to estimate intake of nutrients and, together with supplement usage information, describe total intake of various foods or nutrients. As with all self-reporting methods, these tools are challenging to use and interpret. Yet, they are needed to establish dietary reference intake recommendations and to evaluate what proportion of the population meets these recommendations. While biomarkers are generally expensive and, to some degree, invasive, there is no question as to their ability to assess nutrition status. In some cases biomarkers can also be used to assess intake or function, although rarely can one biomarker fulfill all these purposes. For example, serum folate is a good indicator of folate intake, red blood cell (RBC) folate is a good status indicator, and plasma total homocysteine is a good functional indicator of one-carbon metabolism.Using folate and vitamin D - two vitamins that are currently hotly debated in the public health arena - as two case studies, we discuss the complexities of using biomarkers and total intake information to assess nutrition status. These two examples also show how biomarkers and intake provide different information and how both are needed to evaluate and set public health policy. We also provide guidance on general requirements for using nutrition biomarkers and food and supplement intake information in longitudinal, population-based surveys.
Food & Nutrition Research 01/2012; 56.
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Karen W Phinney,
Mary Bedner,
Susan S-C Tai,
Veronica V Vamathevan,
Lane C Sander,
Katherine E Sharpless,
Stephen A Wise,
James H Yen, Rosemary L Schleicher,
Madhulika Chaudhary-Webb,
Christine M Pfeiffer,
Joseph M Betz,
Paul M Coates,
Mary Frances Picciano
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ABSTRACT: The National Institute of Standards and Technology (NIST), in collaboration with the National Institutes of Health's Office of Dietary Supplements (NIH-ODS), has developed a Standard Reference Material (SRM) for the determination of 25-hydroxyvitamin D [25(OH)D] in serum. SRM 972 Vitamin D in Human Serum consists of four serum pools with different levels of vitamin D metabolites and has certified and reference values for 25(OH)D(2), 25(OH)D(3), and 3-epi-25(OH)D(3). Value assignment of this SRM was accomplished using a combination of three isotope-dilution mass spectrometry approaches, with measurements performed at NIST and at the Centers for Disease Control and Prevention (CDC). Chromatographic resolution of the 3-epimer of 25(OH)D(3) proved to be essential for accurate determination of the metabolites.
Analytical Chemistry 12/2011; 84(2):956-62. · 5.86 Impact Factor
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ABSTRACT: An ultra performance liquid chromatography-tandem mass spectrometry method with calibration traceable to NIST SRM was developed and validated to measure concentrations of 25-hydroxyvitamin D(2) (25OHD(2)), 25-hydroxyvitamin D(3) (25OHD(3)) and the C-3 epimer of 25OHD(3) (epi-25OHD(3)) in human serum.
Tri- and hexa-deuterated internal standards were added to serum (100 μl) to monitor recovery. Liquid-liquid extraction was used to extract the hexane-soluble materials. Calibration solutions [8-100 nmol/L 25OHD(2,) 12-150 nmol/L 25OHD(3), and 4-50 nmol/L epi-25OHD(3)] prepared in phosphate-buffered saline containing 4% albumin were similarly processed. Using a pentafluorophenyl column (2.1×100 mm) and isocratic methanol/water (72/28, v/v) flowing at 0.4 ml/min, run time was 14 min per sample; 25OHD(3) and epi-25OHD(3) were baseline separated. Atmospheric pressure chemical ionization in the positive ion mode with selected reaction monitoring captured the following transitions: 25OHD(2), m/z 395.3>377.3 (209.1 qualifier); (epi-)25OHD(3), m/z 383.3>365.3 (105.1 qualifier); d(3)-25OHD(2), m/z 398.3>380.3; and d(6)-25OHD(3), m/z 389.3>371.3.
Recovery averaged ≥98%. Total imprecision was ≤10% when concentrations were ≥20 nmol/l. Bias averaged <5%. Detection limits were <5 nmol/l. Median (nmol/l) 25OHD(2), 25OHD(3) and epi-25OHD(3) were quantitated in 98 blood donors (<LOD, 56.0, <LOD) and 35 pregnant women (<LOD, 87.6, 3.70).
This method is highly accurate, precise and specific.
Clinica chimica acta; international journal of clinical chemistry 08/2011; 412(17-18):1594-9. · 2.54 Impact Factor
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ABSTRACT: The Institute of Medicine (IOM) recently released new dietary reference intakes for calcium and vitamin D. The IOM defined four categories of vitamin D status based on serum 25-hydroxyvitamin D (25OHD): (i) risk of deficiency, (ii) risk of inadequacy, (iii) sufficiency, and (iv) above which there may be reason for concern. This brief presents the most recent national data on vitamin D status in the U.S. population based on these IOM categories. Results are presented by age, sex, race and ethnicity, and, for women, by pregnancy and lactation status.
NCHS data brief 03/2011;
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Elizabeth A Yetley,
Christine M Pfeiffer, Rosemary L Schleicher,
Karen W Phinney,
David A Lacher,
Sylvia Christakos,
John H Eckfeldt,
James C Fleet,
George Howard,
Andrew N Hoofnagle, [......],
Joseph Massaro,
Munro Peacock,
Bernard Rosner,
Donald Wiebe,
Regan L Bailey,
Paul M Coates,
Anne C Looker,
Christopher Sempos,
Clifford L Johnson,
Mary Frances Picciano
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ABSTRACT: A roundtable to discuss monitoring of serum 25-hydroxyvitamin D [25(OH)D] in the NHANES was held in late July 2009. Topics included the following: 1) options for dealing with assay fluctuations in serum 25(OH)D in the NHANES conducted between 1988 and 2006; 2) approaches for transitioning between the RIA used in the NHANES between 1988 and 2006 to the liquid chromatography tandem MS (LC-MS/MS) measurement procedure to be used in NHANES 2007 and later; 3) approaches for integrating the recently available standard reference material for vitamin D in human serum (SRM 972) from the National Institute of Standards and Technology (NIST) into the NHANES; 4) questions regarding whether the C-3 epimer of 25-hydroxyvitamin D3 [3-epi-25(OH)D3] should be measured in NHANES 2007 and later; and 5) identification of research and educational needs. The roundtable experts agreed that the NHANES data needed to be adjusted to control for assay fluctuations and offered several options for addressing this issue. The experts suggested that the LC-MS/MS measurement procedure developed by NIST could serve as a higher order reference measurement procedure. They noted the need for a commutability study for the recently released NIST SRM 972 across a range of measurement procedures. They suggested that federal agencies and professional organizations work with manufacturers to improve the quality and comparability of measurement procedures across all laboratories. The experts noted the preliminary nature of the evidence of the 3-epi-25(OH)D3 but felt that it should be measured in 2007 NHANES and later.
Journal of Nutrition 09/2010; 140(11):2030S-45S. · 3.92 Impact Factor
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ABSTRACT: The goals were to determine the prevalence of vitamin D deficiency among minority children in a southern US city, to examine differences in serum 25-hydroxyvitamin D levels between non-Hispanic black and Hispanic children, and to determine dietary sources of vitamin D.
Low-income, minority children (N = 290; mean age: 2.5 +/- 1.2 years) were recruited during well-child clinic visits. Serum 25-hydroxyvitamin D and calcium levels were measured and dietary information was assessed.
The mean 25-hydroxyvitamin D(3) level was 26.2 +/- 7.6 ng/mL, whereas 25-hydroxyvitamin D(2) was not detected. Overall, 22.3% of children had deficient serum 25-hydroxyvitamin D(3) levels (< or =20 ng/mL), 73.6% had less-than-optimal serum 25-hydroxyvitamin D levels (< or =30 ng/mL), and 1.4% had low serum calcium levels (< or =9 mg/dL). A significantly larger proportion of non-Hispanic black children, compared with Hispanic children, had vitamin D deficiency (26% vs 18%; P < .05). Age and season of recruitment were significantly associated with vitamin D deficiency and low serum calcium levels. Older children (> or =3 years) were less likely to have vitamin D deficiency (odds ratio [OR]: 0.89 [95% confidence interval [CI]: 0.81-0.96]; P < .001). Study enrollment during spring and summer reduced the likelihood of vitamin D deficiency by approximately 20% (spring, OR: 0.85 [95% CI: 0.73-0.98]; P = .03; summer, OR: 0.82 [95% CI: 0.73-0.92]; P < .01). Fortified milk provided most dietary vitamin D (62%), with Hispanic children reporting greater intake.
Suboptimal vitamin D status was common among apparently healthy, low-income, minority children. Age and season were significant predictors of vitamin D deficiency.
PEDIATRICS 03/2010; 125(4):633-9. · 4.47 Impact Factor
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ABSTRACT: Vitamin C (ascorbic acid) may be the most important water-soluble antioxidant in human plasma. In the third National Health and Nutrition Examination Survey (NHANES III, 1988-1994), approximately 13% of the US population was vitamin C deficient (serum concentrations <11.4 micromol/L).
The aim was to determine the most current distribution of serum vitamin C concentrations in the United States and the prevalence of deficiency in selected subgroups.
Serum concentrations of total vitamin C were measured in 7277 noninstitutionalized civilians aged > or =6 y during the cross-sectional, nationally representative NHANES 2003-2004. The prevalence of deficiency was compared with results from NHANES III.
The overall age-adjusted mean from the square-root transformed (SM) concentration was 51.4 micromol/L (95% CI: 48.4, 54.6). The highest concentrations were found in children and older persons. Within each race-ethnic group, women had higher concentrations than did men (P < 0.05). Mean concentrations of adult smokers were one-third lower than those of nonsmokers (SM: 35.2 compared with 50.7 micromol/L and 38.6 compared with 58.0 micromol/L in men and women, respectively). The overall prevalence (+/-SE) of age-adjusted vitamin C deficiency was 7.1 +/- 0.9%. Mean vitamin C concentrations increased (P < 0.05) and the prevalence of vitamin C deficiency decreased (P < 0.01) with increasing socioeconomic status. Recent vitamin C supplement use or adequate dietary intake decreased the risk of vitamin C deficiency (P < 0.05).
In NHANES 2003-2004, vitamin C status improved, and the prevalence of vitamin C deficiency was significantly lower than that during NHANES III, but smokers and low-income persons were among those at increased risk of deficiency.
American Journal of Clinical Nutrition 09/2009; 90(5):1252-63. · 6.67 Impact Factor
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American Journal of Clinical Nutrition 08/2009; 90(3):695. · 6.67 Impact Factor
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ABSTRACT: Changes in serum 25-hydroxyvitamin D [25(OH)D] concentrations in the US population have not been described.
We used data from the National Health and Nutrition Examination Surveys (NHANES) to compare serum 25(OH)D concentrations in the US population in 2000-2004 with those in 1988-1994 and to identify contributing factors.
Serum 25(OH)D was measured with a radioimmunoassay kit in 20 289 participants in NHANES 2000-2004 and in 18 158 participants in NHANES III (1988-1994). Body mass index (BMI) was calculated from measured height and weight. Milk intake and sun protection were assessed by questionnaire. Assay differences were assessed by re-analyzing 150 stored serum specimens from NHANES III with the current assay.
Age-adjusted mean serum 25(OH)D concentrations were 5-20 nmol/L lower in NHANES 2000-2004 than in NHANES III. After adjustment for assay shifts, age-adjusted means in NHANES 2000-2004 remained significantly lower (by 5-9 nmol/L) in most males, but not in most females. In a study subsample, adjustment for the confounding effects of assay differences changed mean serum 25(OH)D concentrations by approximately 10 nmol/L, and adjustment for changes in the factors likely related to real changes in vitamin D status (ie, BMI, milk intake, and sun protection) changed mean serum 25(OH)D concentrations by 1-1.6 nmol/L.
Overall, mean serum 25(OH)D was lower in 2000-2004 than 1988-1994. Assay changes unrelated to changes in vitamin D status accounted for much of the difference in most population groups. In an adult subgroup, combined changes in BMI, milk intake, and sun protection appeared to contribute to a real decline in vitamin D status.
American Journal of Clinical Nutrition 01/2009; 88(6):1519-27. · 6.67 Impact Factor
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ABSTRACT: Carotenoids, vitamin A, and tocopherols serve important roles in many key body functions. However, availability of these compounds may be decreased in patients with short bowel syndrome (SBS) due to decreased oral intake of fruits and vegetables and/or decreased intestinal absorption. Little information is available on serum concentrations of carotenoids, vitamin A, and tocopherols during chronic parenteral nutrition (PN) or during PN weaning. The aim of this study was to prospectively examine serum concentrations of a wide variety of carotenoids, vitamin A, and tocopherols in patients with SBS undergoing an intensive 12-wk intestinal rehabilitation program.
Twenty-one PN-dependent adult patients with SBS were enrolled in a 12-wk intestinal rehabilitation program, which included individualized dietary modification, multivitamin supplementation, and randomization to receive subcutaneous placebo (n = 9) or human growth hormone (0.1 mg . kg(-1) . d(-1); n = 12). PN weaning was initiated after week 4 and advanced as tolerated. Serum concentrations of carotenoids, vitamin A, and tocopherols were determined at baseline and at weeks 4 and 12.
A significant percentage of subjects exhibited low serum concentrations for carotenoids and alpha-tocopherol at study entry, and a few subjects had low concentrations of retinol (5%). Carotenoid and vitamin A valves did not improve over time, while alpha-tocopherol levels rose. Serum alpha-tocopherol concentration was negatively associated with PN lipid dose (r = -0.34, P < 0.008).
Patients with SBS are depleted in diet-derived carotenoids despite oral and intravenous multivitamin supplementation and dietary adjustment during intestinal rehabilitation and PN weaning. Reduction of PN lipid infusion may improve serum alpha-tocopherol concentrations.
Nutrition 12/2008; 25(4):400-7. · 3.03 Impact Factor
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ABSTRACT: Environmental conditions during sample processing, shipping, and storage are often suboptimal, particularly in less developed countries. We used samples from US volunteers to investigate the effects of delayed whole blood (WB) processing and delayed freezing of serum on selected nutritional indicators.
WB tubes (n = 35) were either stored at 32 degrees C for up to 3 days before serum separation or centrifuged within 2 h of collection; serum samples were stored at 11 degrees C for up to 14 days to simulate delayed shipping. We assessed analyte stability by comparing results with data from optimally prepared/stored serum samples (<2 h on the clot, frozen at -70 degrees C) and by using clinical-acceptability criteria based on combined analytical imprecision and intraindividual biologic variability.
Clinically acceptable changes in concentration varied from 3%-15%. Delayed WB processing did not unacceptably affect concentrations of carotenoids and vitamins B(12), D, and E; however, we obtained clinically unacceptable changes for ferritin (+9%), soluble transferrin receptor (sTfR) (+5%), and folate (-30%) after 1 day, and for vitamin A (-10%) after 3 days. Delayed freezing of serum did not affect concentrations of ferritin, sTfR, carotenoids, and vitamins A, B(12), and E; however, we obtained clinically unacceptable changes for vitamins C (-20%) and D (+7%) after 7 days and for folate after 14 days (-22%).
Despite substantial delays in WB processing or in the freezing of serum samples, most nutritional indicators showed remarkable stability. This information is important for both the design of field studies and the use of residual samples subjected to suboptimal preanalytical factors.
Clinical Chemistry 09/2008; 54(11):1883-91. · 7.91 Impact Factor
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ABSTRACT: Essential to the conduct of epidemiologic studies examining aflatoxin exposure and the risk of heptocellular carcinoma, impaired growth, and acute toxicity has been the development of quantitative biomarkers of exposure to aflatoxins, particularly aflatoxin B(1). In this study, identical serum sample sets were analyzed for aflatoxin-albumin adducts by ELISA, high-performance liquid chromatography (HPLC) with fluorescence detection (HPLC-f), and HPLC with isotope dilution mass spectrometry (IDMS). The human samples analyzed were from an acute aflatoxicosis outbreak in Kenya in 2004 (n = 102) and the measured values ranged from 0.018 to 67.0, nondetectable to 13.6, and 0.002 to 17.7 ng/mg albumin for the respective methods. The Deming regression slopes for the HPLC-f and ELISA concentrations as a function of the IDMS concentrations were 0.71 (r(2) = 0.95) and 3.3 (r(2) = 0.96), respectively. When the samples were classified as cases or controls, based on clinical diagnosis, all methods were predictive of outcome (P < 0.01). Further, to evaluate assay precision, duplicate samples were prepared at three levels by dilution of an exposed human sample and were analyzed on three separate days. Excluding one assay value by ELISA and one assay by HPLC-f, the overall relative SD were 8.7%, 10.5%, and 9.4% for IDMS, HPLC-f, and ELISA, respectively. IDMS was the most sensitive technique and HPLC-f was the least sensitive method. Overall, this study shows an excellent correlation between three independent methodologies conducted in different laboratories and supports the validation of these technologies for assessment of human exposure to this environmental toxin and carcinogen.
Cancer Epidemiology Biomarkers & Prevention 07/2008; 17(7):1653-7. · 4.12 Impact Factor
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ABSTRACT: Measurement of vitamin D molecules are important in the management of patients with bone disease. We developed a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to measure 25OHD(3) and 25OHD(2) in human serum and compared it to the traditionally used DiaSorin radioimmunoassay (RIA).
Serum samples (200 microl) were treated with acetonitrile and centrifuged to remove protein. An online solid-phase extraction procedure was used. Calibration solutions (5-100 ng/ml) of 25OHD(2) and 25OHD(3) were prepared using 4% albumin in phosphate-buffered saline. Chromatography: C18 column, isocratic ethanol/water (83/17, v/v). Mass spectrometry system: atmospheric pressure chemical ionization in the positive ion mode. Transitions: 25OHD(3), m/z 401.4-->383.4; 25OHD(2), m/z 413.4-->395.4; and the internal standard hexadeuterated-25OHD(3), m/z 407.7-->389.7.
Detection limits were 0.49 ng/ml (25OHD(3)) and 1.86 ng/ml (25OHD(2)). Intra- and inter-assay coefficients of variation (CV) were <7% and <11%, respectively, for 25OHD(3) and <9% and <16%, respectively, for 25OHD(2). Recovery averaged (SD) 99% (2%) for 25OHD(3) and 95% (0.8%) for 25OHD(2). In a method comparison of 551 specimens from the National Health and Nutrition Examination Survey, the LC-MS/MS method gave values that were on average 13% higher (95%CI: 11-15%) than RIA results.
This high throughput candidate reference method requires minimal sample preparation and is suitable for routine use for analysis of vitamin D status.
Clinica Chimica Acta 05/2008; 391(1-2):6-12. · 2.54 Impact Factor
