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United States Department of Agriculture

Agricultural Research Service

Research Project: Dietary Guidelines Adherence and Healthy Body Weight Maintenance Title: Calculation of total meal d13C from individual food d13C.

Authors
item Casperson, Shanon
item Scholler, Dale -
item Johnson, Luann -
item Whigham Grendell, Leah

Submitted to: Federation of American Societies for Experimental Biology Conference
Publication Type: Abstract Only
Publication Acceptance Date: January 15, 2014
Publication Date: April 30, 2014
Citation: Casperson, S.L., Scholler, D.A., Johnson, L.K., Whigham Grendell, L.D. 2014. Calculation of total meal d13C from individual food d13C.. Federation of American Societies for Experimental Biology Conference. 28:813.2.

Technical Abstract: Variations in the isotopic signature of carbon in biological samples can be used to distinguish dietary patterns and monitor shifts in metabolism. But for these variations to have meaning, the isotopic signature of the diet must be known. We sought to determine if knowledge of the 13C isotopic abundance (d13C) of individual foods can be used to reliably calculate the d13C of a mixed meal. Aliquots of 60 individual foods and 21 meals comprised of those foods were freeze-dried, ground, weighed, and analyzed using an isotope ratio mass spectrometer. The d13C of the individual foods were then used to calculate the d13C of meals comprised of those foods and compared to the analyzed d13C of the corresponding meal. The calculation was weighted such that the contribution of individual foods to the isotopic signature of the meal was relative to the caloric contribution of the food item to the total caloric content of the meal. The measured d13C (-23.76‰) and calculated meals d13C (-23.72‰) did not differ (-0.04‰, 95% CI = -0.30 to 0.22‰) with limits of agreement (+/- 2SD) of -1.20 – 1.12‰, and the difference was not dependent upon the magnitude of the d13C by Bland-Altman regression (slope = -0.17, p = 0.88). In conclusion, an approximation of the isotopic signature of whole meals can easily and accurately be calculated when the analysis of each meal is not feasible. These results will aid in the characterization of individual dietary intake.

Last Modified: 11/26/2014
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