2011 Annual Report
1a.Objectives (from AD-416)
Our long-term objective is to provide reliable estimates for the composition of dietary supplement (DS) products due to their increasing prevalence of use. An analytically based composition database of representative values of nutrients and other ingredients in dietary supplement products consumed by the U.S. population is being developed. This database will improve accuracy in estimating the contribution of dietary supplements to total dietary intakes of nutrients and thus will result in a better evaluation of the nutritional status of Americans. Over the next 5 years we will focus on the following objectives:
Objective 1: Determine and monitor the nutrient and other ingredient composition of dietary supplements commonly consumed by Americans. Compile, maintain, and disseminate electronic dietary supplement composition databases utilizing standardized approaches according to specified timelines.
Objective 2: Evaluate and update methods for the acquisition, evaluation, compilation and dissemination of dietary supplement composition data utilizing new, robust computerized systems.
Objective 3: Investigate the variability of dietary supplement composition data attributable to inherent supplement differences, analytical methodology, and other contributing factors.
1b.Approach (from AD-416)
Objective 1: NDL will develop estimates of the nutrient and other ingredient content of high priority dietary supplement (DS) products and disseminate dietary supplement databases on a bi-annual basis. This research will include the identification of high priority dietary supplement products and ingredients according to prevalence of consumption, public health interest in specific ingredients, and the availability of reliable analytical methods for specific compounds. Studies of dietary supplements composition for various product types including user groups by age and/or gender will be conducted. Samples will be analyzed by qualified laboratories which demonstrate expertise in the analysis of dietary supplement components and matrices. Scientists will review and evaluate laboratory data for accuracy and precision and will apply appropriate statistical techniques to final data for estimation of dietary supplement component amounts.
Objective 2: NDL will develop and validate methods for data acquisition (e.g., USDA analytical data, industry data), including statistical sampling, sample handling, laboratory methodology, and data quality evaluation, to ensure representative and accurate dietary supplement ingredient estimates. For analytical studies managed by NDL, statistical sampling plans for the analysis of dietary supplements will continue to be developed based upon market share and ingredient label information. NDL will include available Standard Reference Materials (SRMs) when sending batches of samples to the laboratory for analysis. NIST recommendations for the analysis of ingredients in SRMs, including stability information and extraction and homogenization procedures will be used in the development and evaluation of NDL laboratory protocols for contracted labs.
Objective 3: NDL will investigate the variability of dietary supplement composition data attributable to inherent supplement differences, analytical methodology, and other contributing factors. The magnitude of variability attributable to the measurement process will vary for each ingredient or ingredient group (i.e., minerals analyzed by inductively-coupled plasma spectroscopy (ICP)) and can confound the results for variability inherent in a product. In addition, the assessment of individual ingredient variability will be a factor in determining sample sizes for future analytical studies.
NDL is continuing to work with the Office of Dietary Supplements, National Institutes of Health, to further develop the Dietary Supplement Ingredient Database (DSID) to support public health research. A key goal is to report analytical levels of nutrients and other bioactive components in dietary supplements. DSID supports estimation of total nutrient intake by providing analytical nutrient estimates from supplements, to complement databases which report only label values. Data were made available in the Dietary Supplement Ingredient Database, Release 1 (www.dietarysupplementdatabase.usda.nih.gov), including regression equations for each nutrient for application to products at specific labeled levels. Codes were provided to link estimates to adult MVMs reported in the National Health and Nutrition Examination Survey (NHANES). The availability of the DSID is significant, since it is the first time that analytically based dietary supplement data resulting from federally-sponsored research have been made publicly available.
Studies are underway for ingredient analysis in children’s MVMs, over-the-counter prenatal MVMs, and omega-3 fatty acid supplements. Statistical sampling plans were developed for all studies, identifying representative products and market channels. Up to 6 lots per product were purchased nationwide. Nutrient components were analyzed by qualified laboratories using validated methods, reference materials, and duplicates to monitor precision and accuracy.
In 2011, NDL made research progress on four studies:
Children’s MVMs: Analytical data for 19 nutrients in multiple lots of 65 products were statistically evaluated to estimate the relationship between label and analytical values and to assess variability in children’s MVMs. The data will be linked to NHANES and released in FY 2012.
Prenatal MVMs: Analytical laboratory data for 22 nutrients were obtained for multiple lots of 48 retail and 23 direct sales products, to examine the relationship between label and analytical values and to assess variability in over-the-counter prenatal MVMs.
Omega-3 supplements: Analytical data were obtained for omega-3 fatty acid supplements representing the lower market share. Statistical analysis was initiated to assess omega-3 levels in multiple lots of over 80 supplement products.
Adult MVMs, 2nd study: A statistically based sampling plan was developed using DSID-1 results to determine statistical parameters for selecting representative adult MVM products in mass market, natural/health, and direct sales market channels. Nationwide product purchase began. Vitamin D, vitamin A, iodine, and chromium are being emphasized due to public health interest.
NDL scientists worked with IT consultants to finalize database system requirements and develop a modular design for the Dietary Supplement Ingredient System (DSIS). NDL scientists reported DSID progress in reports at meetings of Experimental Biology, the American Dietetic Association, and an ODS-sponsored iodine seminar.