Vitamin C Status of US Adults Assessed as Part of the National Health and Nutrition Examination Survey Remained Unchanged between 2003-2006 and 2017-2018.

Background: We compared serum vitamin C (VIC) status of the adult (≥20 y) US population in the National Health and Nutrition Examination Survey (NHANES) 2017-2018 with combined data from 2003-2004 and 2005-2006.

Methods: VIC was measured using HPLC with electrochemical detection. Mean data were stratified by age, sex, race/Hispanic origin, income, body mass index, dietary intake, supplement use, and smoking status.

Supplemental Vitamin D Increased Serum Total 25-Hydroxyvitamin D in the US Adult Population During 2007-2014.

Background: Data from the 2007-2010 NHANES suggested that vitamin D supplements contributed to increased serum concentrations of 25-hydroxyvitamin D [25(OH)D] in the US population.

Objectives: We sought to determine whether 25(OH)D continued to increase during NHANES 2011-2014 and whether associations of 25(OH)D with preselected covariates differed across time periods.

Methods: For this study, 25(OH)D was measured in adults (≥20 y) using LC-MS/MS.

Retinol-binding protein, retinol, and modified-relative-dose response in Ugandan children aged 12-23 months and their non-pregnant caregivers.

Retinol-binding protein (RBP), retinol, and modified-relative-dose response (MRDR) are used to assess vitamin A status. We describe vitamin A status in Ugandan children and women using dried blood spot (DBS) RBP, serum RBP, plasma retinol, and MRDR and compare DBS-RBP, serum RBP, and plasma retinol. Blood was collected from 39 children aged 12-23 months and 28 non-pregnant mothers aged 15-49 years as a subsample from a survey in Amuria district, Uganda, in 2016.

An HPLC Ultraviolet Method Using Low Sample Volume and Protein Precipitation for the Measurement of Retinol in Human Serum Suitable for Laboratories in Low- and Middle-Income Countries.

Background: Assessing vitamin A status in populations remains a high public health priority for low- and middle-income countries. However, analytical difficulties with serum retinol measurements persist in international laboratories. Nearly all participants in a Centers for Disease Control and Prevention external quality assessment program use HPLC to measure serum retinol, but round-to-round results failing to meet acceptable criteria suggest the need to provide a straightforward stable HPLC ultraviolet (UV) method that can be adopted by these laboratories to improve performance.

Vitamin D status in the United States, 2011-2014.

Background: Vitamin D is important for bone health; in 2014 it was the fifth most commonly ordered laboratory test among Medicare Part B payments.

Objectives: The aim of this study was to describe vitamin D status in the US population in 2011-2014 and trends from 2003 to 2014.

Methods: We used serum 25-hydroxyvitamin D data from NHANES 2011-2014 (n = 16,180), and estimated the prevalence at risk of deficiency (<30 nmol/L) or prevalence at risk of inadequacy (30-49 nmol/L) by age, sex, race and Hispanic origin, and dietary intake of vitamin D.

Quality specifications and their daily application to evaluate the accuracy of reference measurements for serum concentrations of 25-hydroxyvitamin D and 25-hydroxyvitamin D.

Background: Reference measurement procedures (RMP) have rigorous accuracy specifications. For total 25-hydroxyvitamin D, 25(OH)D, bias ≤1.7% and CV ≤5% are recommended.

Global prevalence and disease burden of vitamin D deficiency: a roadmap for action in low- and middle-income countries.

Vitamin D is an essential nutrient for bone health and may influence the risks of respiratory illness, adverse pregnancy outcomes, and chronic diseases of adulthood. Because many countries have a relatively low supply of foods rich in vitamin D and inadequate exposure to natural ultraviolet B (UVB) radiation from sunlight, an important proportion of the global population is at risk of vitamin D deficiency. There is general agreement that the minimum serum/plasma 25-hydroxyvitamin D concentration (25(OH)D) that protects against vitamin D deficiency-related bone disease is approximately 30 nmol/L; therefore, this threshold is suitable to define vitamin D deficiency in population surveys.

Long-Term Stability of 18 Nutritional Biomarkers Stored at -20 °C and 5 °C for up to 12 Months.

Background: Consistent information on long-term storage stability for a broad range of nutritional biomarkers is lacking. We investigated the stability of 18 biomarkers stored at suboptimal temperatures (-20 °C and 5 °C) for up to 12 months.

Methods: Multiple vials of serum or whole blood pools (3 concentrations) were stored at -20 °C or 5 °C, removed from the -20 °C freezer after 3, 6, 9, and 12 months and from the 5 °C refrigerator after 6 and 12 months, and placed into a -70 °C freezer until analysis at study completion.

Standard Reference Material (SRM) 2378 fatty acids in frozen human serum. Certification of a clinical SRM based on endogenous supplementation of polyunsaturated fatty acids.

Dietary fatty acids can be both beneficial and detrimental to human health depending on the degree and type of saturation. Healthcare providers and research scientists monitor the fatty acid content of human plasma and serum as an indicator of health status and diet. In addition, both the Centers for Disease Control & Prevention (CDC) and the National Institutes of Health - Office of Dietary Supplements are interested in circulating fatty acids (FAs) because they may be predictive of coronary heart disease.

Association of vitamin D intake and serum levels with fertility: results from the Lifestyle and Fertility Study.

Objective: To evaluate the role of vitamin D intake and serum levels on conception of clinical pregnancy and live birth.

Design: Prospective cohort study.

Setting: Academic medical centers.

Effects of preanalytical factors on hemoglobin measurement: A comparison of two HemoCue® point-of-care analyzers.

Background: In field studies, hemoglobin (Hb) is often measured using a battery-operated, portable HemoCue® hemoglobinometer.

Methods: We compared the performance of 2 HemoCue® models (Hb-201+ and Hb-301) and investigated effects of preanalytical factors on Hb results by simulating unfavorable field conditions.

Results: The Hb-301 produced 2.

Development of an Improved Standard Reference Material for Vitamin D Metabolites in Human Serum.

The National Institute of Standards and Technology (NIST) has developed Standard Reference Material (SRM) 972a Vitamin D Metabolites in Frozen Human Serum as a replacement for SRM 972, which is no longer available. SRM 972a was developed in collaboration with the National Institutes of Health's Office of Dietary Supplements. In contrast to the previous reference material, three of the four levels of SRM 972a are composed of unmodified human serum.

Challenges and Lessons Learned in Generating and Interpreting NHANES Nutritional Biomarker Data.

For the past 45 y, the National Center for Health Statistics at the CDC has carried out nutrition surveillance of the US population by collecting anthropometric, dietary intake, and nutritional biomarker data, the latter being the focus of this publication. The earliest biomarker testing assessed iron and vitamin A status. With time, a broad spectrum of water- and fat-soluble vitamins was added and biomarkers for other types of nutrients (e.

Interlaboratory analytical comparison of fatty acid concentrations in serum or plasma.

Background: There are a large number of clinical studies focusing on the measurement of individual fatty acids in serum or plasma; however, few studies have focused on the interlaboratory comparisons of these measurements. The National Institutes of Standards and Technology (NIST), in collaboration with the National Institutes of Health Office of Dietary Supplements (NIH-ODS) and the Centers for Disease Control and Prevention (CDC), has initiated a quality assurance program for assessing and improving the comparability of individual fatty acid measurements in serum and plasma.

Methods: This is a performance-based study so participants are encouraged to use their laboratory's methods for the quantification of the individual fatty acids that they typically measure in the unknown serum or plasma samples along with a control material.

The vitamin D status of the US population from 1988 to 2010 using standardized serum concentrations of 25-hydroxyvitamin D shows recent modest increases.

Background: Temporal trends in the US population's vitamin D status have been uncertain because of nonstandardized serum 25-hydroxyvitamin D [25(OH)D] measurements.

Objective: To accurately assess vitamin D status trends among those aged ≥12 y, we used data from the cross-sectional NHANESs.

Design: A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for measuring 25(OH)D (sum of 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3), calibrated to standard reference materials, was used to predict LC-MS/MS-equivalent concentrations from radioimmunoassay data (1988-2006 surveys; n = 38,700) and to measure LC-MS/MS concentrations (2007-2010 surveys; n = 12,446).

A Method-bridging Study for Serum 25-hydroxyvitamin D to Standardize Historical Radioimmunoassay Data to Liquid Chromatography-Tandem Mass Spectrometry.

Background: Serum concentrations of 25-hydroxyvitamin D (25OHD) were measured for the National Health and Nutrition Examination Survey (NHANES) over the 1988-2006 period using a radioimmunoassay (RIA). In 2010, the Centers for Disease Control and Prevention (CDC) reissued RIA-harmonized 25OHD for NHANES 2004 and 2006, and advised users to adjust the original RIA data from 1988-1994 by using an equation. Beginning with NHANES 2007-2008, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method measured 25OHD.

National Estimates of Serum Total 25-Hydroxyvitamin D and Metabolite Concentrations Measured by Liquid Chromatography-Tandem Mass Spectrometry in the US Population during 2007-2010.

Background: The 2007-2010 NHANES provides the first US nationally representative serum 25-hydroxyvitamin D [25(OH)D] concentrations measured by standardized liquid chromatography-tandem mass spectrometry.

Objective: We describe patterns for total 25(OH)D and individual metabolites in persons aged ≥1 y stratified by race-ethnicity and grouped by demographic, intake, physiologic, and lifestyle variables.

Methods: We measured 25-hydroxycholecalciferol [25(OH)D3], 25-hydroxyergocalciferol [25(OH)D2], and C3-epimer of 25(OH)D3 [C3-epi-25(OH)D3] in serum samples (n = 15,652) from the 2007-2010 cross-sectional NHANES [total 25(OH)D = 25(OH)D3 + 25(OH)D2].

A candidate reference measurement procedure for quantifying serum concentrations of 25-hydroxyvitamin D₃ and 25-hydroxyvitamin D₂ using isotope-dilution liquid chromatography-tandem mass spectrometry.

The inaccuracy of routine serum 25-hydroxyvitamin D measurements hampers the interpretation of data in patient care and public health research. We developed and validated a candidate reference measurement procedure (RMP) for highly accurate quantitation of two clinically important 25-hydroxyvitamin D metabolites in serum, 25-hydroxyvitamin D2 [25(OH)D2] and 25-hydroxyvitamin D3 [25(OH)D3]. The two compounds of interest together with spiked deuterium-labeled internal standards [d 3-25(OH)D2 and d 6-25(OH)D3] were extracted from serum via liquid-liquid extraction.

Planned variation in preanalytical conditions to evaluate biospecimen stability in the National Children's Study (NCS).

Background: Preanalytical conditions encountered during collection, processing, and storage of biospecimens may influence laboratory results. The National Children's Study (NCS) is a planned prospective cohort study of 100,000 families to examine the influence of a wide variety of exposures on child health. In developing biospecimen collection, processing, and storage procedures for the NCS, we identified several analytes of different biochemical categories for which it was unclear to what extent deviations from NCS procedures could influence measurement results.

Changes in the concentrations of biochemical indicators of diet and nutritional status of pregnant women across pregnancy trimesters in Trujillo, Peru, 2004-2005.

Background: In developing countries, deficiencies in essential micronutrients are common, particularly in pregnant women. Although, biochemical indicators of diet and nutrition are useful to assess nutritional status, few studies have examined such indicators throughout pregnancy in women in developing countries.

Methods: The primary objective of this study was to assess the nutritional status of 78 Peruvian women throughout pregnancy for 16 different nutritional indicators including fat-soluble vitamins and carotenoids, iron-status indicators, and selenium.

Is there a reverse J-shaped association between 25-hydroxyvitamin D and all-cause mortality? Results from the U.S. nationally representative NHANES.

Context: A reverse J-shaped association between serum 25-hydroxyvitamin D (25[OH]D) concentration and all-cause mortality was suggested in a 9-year follow-up (1991-2000) analysis of the Third National Health and Nutrition Examination Survey (NHANES III, 1988-1994).

Objective: Our objective was to repeat the analyses with 6 years additional follow-up to evaluate whether the association persists through 15 years of follow-up.

Participants: The study included 15 099 participants aged ≥ 20 years with 3784 deaths.

Serum concentrations of an aflatoxin-albumin adduct in the National Health and Nutrition Examination Survey (NHANES) 1999-2000.

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 a study 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.

Selected physiologic variables are weakly to moderately associated with 29 biomarkers of diet and nutrition, NHANES 2003-2006.

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.