ARS | Publication request: Control Materials for Validating Measurement of Vitamin D in Key Foods for the USDA National Food and Nutrient Analysis Program (NFNAP)

Submitted to: Experimental Biology
Publication Type: Abstract Only
Publication Acceptance Date: December 3, 2007
Publication Date: April 5, 2008
Citation: Holden, J.M., Byrdwell, W.C., Exler, J., Harnly, J.M., Holick, M., Hollis, B., Horst, R., Patterson, K.K., Phillips, K., Wolf, W.R. 2008. Control materials for validating measurement of vitamin D in key foods for the USDA National Food and Nutrient Analysis Program (NFNAP). Experimental Biology, April 5-9, 2008, San Diego, CA.

Technical Abstract: As part of the USDA's NFNAP, data for vitamin D in the National Nutrient Database for Standard Reference are being updated and expanded, focusing on high priority foods contributing to vitamin D intake. Fish and vitamin D fortified orange juice, breakfast cereals, milk, sliced American cheese, and yogurt were sampled (n=446) according to a nationwide statistical plan, to be analyzed by contract laboratories. A lack of certified reference materials for these matrices required development of control materials to ensure accurate measurements from these contracts. Matrix-specific food homogenates (canned salmon and vitamin D fortified cereal, orange juice, milk, and cheese) were prepared and analyzed by six laboratories (including contract, university and government labs) experienced in determining Vitamin D. Initial results showed wide disparity in results between the six laboratories (CV = 26-46%). Subsequent recovery studies, mass spectrometric analysis, verification of standards, and optimization of extraction solvents established reliable concentrations and lack of statistically significant differences (5%-10% CVs) among three labs. These data were used to establish assigned values and tolerance limits for four of the control materials. Results for salmon were not consistent, and further work is required to validate results for that matrix.