Project Number: 1235-52000-062-00
Project Type: Appropriated

Start Date: Feb 20, 2009
End Date: Feb 19, 2014

Objective:
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.

Approach:
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.