Karen Andrews

Summary of an NIH Workshop to Identify Research Needs to Improve the Monitoring of Iodine Status in the United States and to Inform the DRI

The Office of Dietary Supplements (ODS) at the NIH sponsored a workshop on May 12-13, 2011, to bring together representatives from various NIH institutes and centers as a first step in developing an NIH iodine research initiative. The workshop also provided an opportunity to identify research needs that would inform the dietary reference intakes for iodine, which were last revised in 2001. Iodine is required throughout the life cycle, but pregnant women and infants are the populations most at risk of deficiency, because iodine is required for normal brain development and growth. The CDC monitors iodine status of the population on a regular basis, but the status of the most vulnerable populations remains uncertain. The NIH funds very little investigator-initiated research relevant to iodine and human nutrition, but the ODS has worked for several years with a number of other U.S. government agencies to develop many of the resources needed to conduct iodine research of high quality (e.g., validated analytical methods and reference materials for multiple types of samples). Iodine experts, scientists from several U.S. government agencies, and NIH representatives met for 2 d to identify iodine research needs appropriate to the NIH mission.

A system for defining reference materials applicable to all food matrices

Recently the subcommittee on Food Definition of the AOAC INTERNATIONAL Task Force on Methods for Nutrition Labeling proposed a “Food Matrix Organizational System” [4] to systematically judge the applicability of collaboratively studied methods over a range of food matrices. This system describes a food matrix by its location in one of nine sectors in a triangle, with each point of the triangle defined as representing 100% and the opposite side representing 0% of the normalized contents of each of three major components of FAT, PROTEIN and CARBOHYDRATE. Foods falling within the same sector would be chemically similar and thus should behave in a similar analytical manner. This same scheme can be used to select one or two food matrices representing each sector, for development of a series of reference materials representing all foods. The list of 5250 foods contained in the USDA Nutrient Data Base for Standard Reference has been sorted and matched to this schematic to determine the scope of the selection process. In addition the list of foods in the “USDA Data Base for Food Consumption Surveys” has been examined. Results and progress of this selection process are reported.

Analytical ingredient content and variability of adult multivitamin/mineral products: national estimates for the Dietary Supplement Ingredient Database.

BACKGROUND Multivitamin/mineral products (MVMs) are the dietary supplements most commonly used by US adults. During manufacturing, some ingredients are added in amounts exceeding the label claims to compensate for expected losses during the shelf life. Establishing the health benefits and harms of MVMs requires accurate estimates of nutrient intake from MVMs based on measures of actual rather than labeled ingredient amounts. OBJECTIVES Our goals were to determine relations between analytically measured and labeled ingredient content and to compare adult MVM composition with Recommended Dietary Allowances (RDAs) and Tolerable Upper Intake Levels. DESIGN Adult MVMs were purchased while following a national sampling plan and chemically analyzed for vitamin and mineral content with certified reference materials in qualified laboratories. For each ingredient, predicted mean percentage differences between analytically obtained and labeled amounts were calculated with the use of regression equations. RESULTS For 12 of 18 nutrients, most products had labeled amounts at or above RDAs. The mean measured content of all ingredients (except thiamin) exceeded labeled amounts (overages). Predicted mean percentage differences exceeded labeled amounts by 1.5-13% for copper, manganese, magnesium, niacin, phosphorus, potassium, folic acid, riboflavin, and vitamins B-12, C, and E, and by ∼25% for selenium and iodine, regardless of labeled amount. In contrast, thiamin, vitamin B-6, calcium, iron, and zinc had linear or quadratic relations between the labeled and percentage differences, with ranges from -6.5% to 8.6%, -3.5% to 21%, 7.1% to 29.3%, -0.5% to 16.4%, and -1.9% to 8.1%, respectively. Analytically adjusted ingredient amounts are linked to adult MVMs reported in the NHANES 2003-2008 via the Dietary Supplement Ingredient Database (http://dsid.usda.nih.gov) to facilitate more accurate intake quantification. CONCLUSIONS Vitamin and mineral overages were measured in adult MVMs, most of which already meet RDAs. Therefore, nutrient overexposures from supplements combined with typical food intake may have unintended health consequences, although this would require further examination.

Iodine in food- and dietary supplement–composition databases

The US Food and Drug Administration (FDA) and the Nutrient Data Laboratory (NDL) of the USDA Agricultural Research Service have worked independently on determining the iodine content of foods and dietary supplements and are now harmonizing their efforts. The objective of the current article is to describe the harmonization plan and the results of initial iodine analyses accomplished under that plan. For many years, the FDAs Total Diet Study (TDS) has measured iodine concentrations in selected foods collected in 4 regions of the country each year. For more than a decade, the NDL has collected and analyzed foods as part of the National Food and Nutrient Analysis Program; iodine analysis is now being added to the program. The NDL recently qualified a commercial laboratory to conduct iodine analysis of foods by an inductively coupled plasma mass spectrometry (ICP-MS) method. Co-analysis of a set of samples by the commercial laboratory using the ICP-MS method and by the FDA laboratory using its standard colorimetric method yielded comparable results. The FDA recently reviewed historical TDS data for trends in the iodine content of selected foods, and the NDL analyzed samples of a limited subset of those foods for iodine. The FDA and the NDL are working to combine their data on iodine in foods and to produce an online database that can be used for estimating iodine intake from foods in the US population. In addition, the NDL continues to analyze dietary supplements for iodine and, in collaboration with the NIH Office of Dietary Supplements, to publish the data online in the Dietary Supplement Ingredient Database. The goal is to provide, through these 2 harmonized databases and the continuing TDS focus on iodine, improved tools for estimating iodine intake in population studies.

A Free New Dietary Supplement Label Database for Registered Dietitian Nutritionists

The Academy of Nutrition and Dietetics recognizes the importance of including dietary supplements in assessing and planning dietary intakes.1 Dietary supplement (DS) use in the United States has increased markedly during the last 30 years and is now widespread across all segments of society.2,3,4,5,6 Today, over half of adults and a third of US children have used one or more DS within the past 30 days, with multi-vitamin, multi-mineral (MVMM) products especially common.7, 8 Since supplements are now major sources of several nutrients such as calcium and vitamin D in American diets, it is important for registered dietitians and nutritionists (RDNs) to include their contributions when assessing intakes or planning diets.9,10,11 Likewise, for national nutrition surveillance the contributions to nutrient intakes from supplements must be considered in order to identify groups at dietary risk because their intakes fall below the estimated average requirement (EAR) or above the upper tolerable intake level (UL).12 For example, when supplements are included in assessments, the proportion of the United States population that is below the EAR is much less for several vitamins11 and fewer women are “at risk” (defined as below the EAR) for folate intake than when they are not.13,14 For some nutrients, like folic acid, the UL is established based solely for the form that comes from fortificants in foods and in dietary supplements. RDNs, epidemiologists, and public health officials also need accurate dietary supplement databases in order to evaluate possible associations between nutrient intake and disease outcomes. The National Health and Nutrition Examination Survey (NHANES) dietary supplement label database contains label-derived information from supplement products that is updated every two years. Information contained in the database is driven by what is reported by survey participants. The currently available database contains supplement label information for products reported from 1999–2010. While the NHANES DS database provides useful information, it is not comprehensive and is more likely to contain commonly used supplements and less likely to contain infrequently used supplements.15 In fact, MVMM products account for only about half of all supplements used.3 Additionally, not all information from the label is recorded and released in the database. For example, the NHANES database does not contain information such as health claims, other ingredients and warning statements that may have been on the label.

Interlaboratory Trial for Measurement of Vitamin D and 25-Hydroxyvitamin D [25(OH)D] in Foods and a Dietary Supplement Using Liquid Chromatography-Mass Spectrometry

Assessment of total vitamin D intake from foods and dietary supplements (DSs) may be incomplete if 25-hydroxyvitamin D [25(OH)D] intake is not included. However, 25(OH)D data for such intake assessments are lacking, no food or DS reference materials (RMs) are available, and comparison of laboratory performance has been needed. The primary goal of this study was to evaluate whether vitamin D3 and 25(OH)D3 concentrations in food and DS materials could be measured with acceptable reproducibility. Five experienced laboratories from the United States and other countries participated, all using liquid chromatography tandem-mass spectrometry but no common analytical protocol; however, various methods were used for determining vitamin D3 in the DS. Five animal-based materials (including three commercially available RMs) and one DS were analyzed. Reproducibility results for the materials were acceptable. Thus, it is possible to obtain consistent results among experienced laboratories for vitamin D3 and 25(OH)D3 in foods and a DS.

Feasibility of Including Green Tea Products for an Analytically Verified Dietary Supplement Database

The Dietary Supplement Ingredient Database (DSID) is a federally funded, publicly accessible dietary supplement database that currently contains analytically derived information on micronutrients in selected adult and childrens multivitamin and mineral (MVM) supplements. Other constituents in dietary supplement products such as botanicals are also of interest and thus are being considered for inclusion in the DSID. Thirty-eight constituents, mainly botanicals were identified and prioritized by a federal interagency committee. Green tea was selected from this list as the botanical for expansion of the DSID. This article describes the process for prioritizing dietary ingredients in the DSID. It also discusses the criteria for inclusion of these ingredients, and the approach for selecting and testing products for the green tea pilot study.

Is Nutrient Content and Other Label Information for Prescription Prenatal Supplements Different from Nonprescription Products

BACKGROUND Prenatal supplements are often recommended to pregnant women to help meet their nutrient needs. Many products are available, making it difficult to choose a suitable supplement because little is known about their labeling and contents to evaluate their appropriateness. OBJECTIVE To determine differences between prescription and nonprescription prenatal supplements available in the United States regarding declared nutrient and nonnutrient ingredients and the presence of dosing and safety-related information. DESIGN Using two publicly available databases with information about prenatal supplement products, information from prescription and nonprescription product labels were extracted and evaluated. For the 82 prescription and 132 nonprescription products, declared label amounts of seven vitamins and minerals, docosahexaenoic acid (DHA), the presence of other nonnutrient components, and the presence of key safety and informational elements as identified in two Department of Health and Human Services Office of Inspector General (OIG)s 2003 reports were compiled and compared. RESULTS Compared with nonprescription products, prescription products contained significantly fewer vitamins (9±0.2 vs 11±0.3; P≤0.05) and minerals (4±0.1 vs 8±0.3; P≤0.05). Declared amounts of folic acid were higher in prescription products, whereas vitamin A, vitamin D, iodine, and calcium were higher in the nonprescription products. Amounts of iron, zinc, and DHA were similar. Virtually all products contained levels of one or more nutrients that exceeded the Recommended Dietary Allowances for pregnant and/or lactating women. Product type also influenced ingredients added. Fewer prescription products contained botanical ingredients (6% prescription vs 33% nonprescription) and probiotics (2% prescription vs 8% nonprescription). Only prescription products contained the stool softener docusate sodium. CONCLUSIONS Our analysis of prenatal supplements indicates that prescription and nonprescription supplements differ in terms of declared composition and nutrient strength, but have labels that are similarly sparse regarding aspects of use such as dosing information.

Analysis of individual foods for the validation of sugars and starch contents of composited diets

Abstract Two similar total daily diets were collected for each of three caloric levels. From these, six diet composites and the 21 commonly eaten individual foods which made up the composites were analyzed for their sugar and starch contents. Sugars were extracted into 80% methanol. Extracts were dried, derivatized, and analyzed by gas-liquid chromatography (GLC). The residue after methanol extraction was incubated with an enzyme/buffer solution for starch hydrolysis and the resulting glucose was again determined by GLC. From the data, the sum of all sugars (i.e., fructose, glucose, lactose, maltose, sucrose) and the amount of starch as calculated from the analyzed values for each individual food are comparable to values obtained simply by analyzing the composited total diets. This finding validates the analyzed “available carbohydrate” data of composites. However, a large variation was found between analyzed “available carbohydrate” and calculated “total carbohydrate” values from food tables.

TDRM workshop on reference materials at the AOAC annual meeting 2015: How do I set up proper inter-laboratory comparison with testing materials I have prepared myself?

This workshop was prepared and conducted by the Technical Division on Reference Materials (TDRM) of the AOAC and was the fifth in a series following: ‘‘It’s an Emergency! We Need a Reference Material Now! Key Learnings About Reference Materials from Past Emergencies’’ (2014), ‘‘Building the use of Certified Reference Materials into dispute resolution’’ (2013), ‘‘The use of reference materials to enable accuracy/trueness in analytical method validation/verification’’ (2012) and ‘‘Reference materials in laboratory accreditation’’ (2011). The 2011, 2012 and 2013 workshops were summarized as meeting reports in Accreditation and Quality Assurance [1–3], whereas no meeting report was published after the 2014 meeting. At the 2015 AOAC Annual Meeting in Los Angeles, the workshop was held to discuss setting up a proper inter-laboratory comparison with testing materials that have been prepared within the laboratory. The workshop consequently addressed a common problem for many laboratories: the need for a specific reference material, when the specific test material may not be commercially available, and hence, it has to be prepared in-house. Approximately 75 participants were in attendance of this workshop mainly from the food and feed industry, universities and authorities active in this field.