Location: Nutrient Data Laboratory2014 Annual Report
1a. Objectives (from AD-416):
The Dietary Supplement Ingredient Database (DSID) (http://dsid.usda.nih.gov; (U.S. Department of Agriculture, 2012) currently provides nationally representative supplement composition data for adult and children’s MVM, based on chemical analysis. All other dietary supplement databases contain label information only. In addition to the evaluation of vitamin and mineral levels in dietary supplements, the DSID will be expanded to include supplements with other ingredients of interest, including omega-3 (n-3) fatty acids in fish and plant oil supplements, and catechins, caffeine, and flavonoids in botanical supplements. Objective 1: Determine, evaluate, and expand knowledge about the composition of frequently consumed dietary supplements in the U.S. by collecting and compiling data and information on essential nutrients and emerging components of public health importance. This includes developing methods for sampling new dietary supplement product types, statistically evaluating analytical results to portray representative estimates, and improving the value of the Dietary Supplement Ingredient Database by utilizing new technologies to generate novel datasets.
1b. Approach (from AD-416):
Several types of studies are planned, including ongoing national and monitoring studies and new pilot and national studies. NDL will design and carry out research to analytically determine the ingredient composition of representative dietary supplements, including essential nutrients and bioactive components. NDL will identify laboratories for sample analysis and evaluate data quality. Results will be statistically evaluated and made publicly available through the DSID. On-going DSID Studies: 1) Omega-3 fatty acid national study: scientifically evaluate the relationships between labeled and analytical levels of omega-3 fatty acids in representative dietary supplements, including fish oil, plant oil and fish/plant oil blends. Release mean results and variability information from this study in DSID-3. 2) Over-the-Counter (OTC) prenatal MVM national study: scientifically evaluate the relationship between label and analytical values and assess the variability for up to 22 vitamins and minerals in OTC prenatal MVM. Release mean results and variability information from this study in DSID-3. 3) Adult MVM monitoring study: systematically evaluate the statistical relationships between label and analytical data since the first adult MVM study in a monitoring study of adult MVM, and release results in DSID-4. The information from this study will be used to plan the frequency and scope of updates to DSID for other MVM and possibly other supplement categories. Pilot Studies: 1) Green tea study AND flavonoid-containing dietary supplements (DS) study: methods of analysis will be evaluated by testing representative and top-selling products for prioritized ingredients of interest. 2) Calcium in DS and OTC antacids study: DS and OTC antacids, a major source of supplemental calcium intake in the U.S., will be assessed for their calcium and vitamin D content. National Studies: 1) Green tea DS and flavonoid-containing DS studies: obtain mean estimates for and measures of variability for analyzed catechins, caffeine, and for analyzed flavonoids (such as flavonols, flavones, flavanones, catechins, and anthocyanidins) in nationally representative botanical DS. 2) Calcium in DS and OTC antacids study: determine national estimates for ingredients in calcium-containing DS, a commonly reported supplement
3. Progress Report:
NDL continues to collaborate with the Office of Dietary Supplements, National Institutes of Health, to optimize and expand the Dietary Supplement Ingredient Database (DSID), which supports public health research. DSID supports a more accurate estimation of total ingredient intakes from foods and dietary supplements. Botanical DSID initiative: green tea pilot study. A botanical initiative for the DSID is now underway to evaluate levels of ingredients and ingredient constituents in botanical dietary supplements (DS). However, supplement labels provide only partial information about levels of bioactive components in botanicals. Complete composition information for botanicals must be determined analytically so researchers can obtain more accurate estimates of total intake for these bioactives. Green tea is a botanical ingredient that is commonly consumed and studied for its health benefits. A pilot study of green tea-containing DS is in progress, with 3 participating laboratories. The goals of the pilot study are: • Evaluate methods of analysis by testing representative and top-selling products for prioritized ingredients of interest • Obtain estimates of content and variability for individual catechins, caffeine and other ingredients in green tea DS • Identify options for applying analytical results to various types of label information • Determine the criteria and scope for the next study Three National Institute of Standards (NIST) green tea Standard Reference Materials (SRMs) are being sent with product samples in order to evaluate accuracy and precision of the laboratory data. Adult, children’s and OTC prenatal MVM studies: a newly amended statistical procedure for regression model selection. The purpose of the adult, children’s, and OTC prenatal MVM studies is to examine the relationship between label and analytical values and assess the variability for vitamins and minerals in representative products. Using statistical sampling plans, national samplings of 66-109 DS products were purchased, from mass market, natural health and direct channels. Multiple lots of each product in each study were sent to qualified labs with quality control materials for the analysis of vitamins and minerals. The DSID team, in collaboration with a consultant statistician, made changes in the statistical analysis of the finalized laboratory results. Statistical tools were amended to identify the best regression model for predicting percent differences in nutrient analytical content from DS labels. A new influence test was introduced based on the mean model. A new model validation test at the supplement level replaced the validation at the individual observation level. The impact of label gap rule applications on the best fit regression models was studied and allowed to expand the label ranges for regression models. The data across the MVM studies were reanalyzed in accordance with the new procedure for regression model selection. Regression analyses of differences in analytical content from label claims were conducted using mean, linear, and quadratic models. The new model selection procedure will be applied in the manuscripts on the adult and children’s MVM, in the calculators of analytically estimated vitamin and mineral content to be released in DSID-3, and in the analysis of data obtained by adult MVM-2 monitoring study. OTC prenatal MVM study: The purpose of the OTC prenatal MVM study is to examine the relationship between label and analytical values and assess the variability for vitamins and minerals in representative products. Using a statistical sampling plan, 71 DS products were purchased, with 16 from mass market, 45 from natural health and 33 from direct channels. Multiple lots of each product were sent to qualified labs with quality control materials for the analysis of vitamins and minerals. NDL completed statistical analysis of OTC prenatal MVMs data for DSID-3 release. Adult MVM 2 study: The purpose of this study is to monitor changes in the statistical relationships between label and analytical data since the first adult MVM study (begun in 2006). In addition, new ingredients will be added to the DSID for this product category, which is the most commonly reported dietary supplement category in NHANES studies. Vitamins A and D, iodine, and chromium are a particular focus due to ODS/public health interest and major improvements in analytical methodology for these ingredients. The initial laboratory results for multiple lots of 124 supplements purchased from multiple channels have been reviewed. Results for individual lots of products were compared to each other and to labeled levels. Sample retests to double-check questionable, high or low ingredient values have been identified and sent for lab analysis. The results for >30 retest batches from 3 laboratories were reviewed. Omega-3 fatty acid study: The purpose of the omega-3 study is to investigate the relationship between labeled and analytical levels of omega-3 fatty acids in representative dietary supplements, including fish oil, plant oil, and fish/plant oil blends. Multiple lots of over 80 fish oil, flax oil, and fish/plant blend products were purchased from mass market, specialty, and direct sales channels. Data analysis has focused on laboratory results for the major omega-3 fatty acids, alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Two labs were used to analyze the samples. Lab results for this study were finalized. NDL researched NHANES 07-10 DS files and prepared a final product weight as an indicator of market share for each product in the study. These final product weights will be applied in regression analyses of ingredients in omega-3 supplements for the next DSID release.