TITLE:  Human δ15N: indicator of diet, geographic origin or metabolism?

AUTHORS: Frank Huelsemann1,2, Ulrich Flenker1,2, Karsten Koehler1,2,3 and Wilhelm Schaenzer1

PRESENTING AUTHOR:    Frank Huelsemann

ADDRESS

1. Institute of Biochemistry, German Sport University Cologne, Am Sportpark Müngersdorf 6, 50933 Cologne, Germany.
2. The German Research Centre of Elite Sport, German Sport University Cologne, Am Sportpark Müngersdorf 6, 50933 Cologne, Germany.
3. Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802, USA

Presenting author:
f.huelsemann@biochem.dshs-koeln.de, Tel.: 0049 (0) 221 4982 5060, Fax: 0049 (0) 221 4973 236

PREFERED PRESENTATION:   ORAL 

KEY WORDS: stable nitrogen isotopes, dietary reconstruction, provenance, metabolism, hair analysis, dietary change     

ABSTRACT:
Beside other elements stable nitrogen isotope ratios (δ15N) of human tissue are used for reconstruction of dietary habits and geographic allocation of populations and individuals. In principle, δ15N of a tissue is reflected by the individual diet, which might be influenced by metabolism and/or geographical variables. However, knowledge concerning the fundamental principles controlling δ15N in humans is limited.
In order to study the effect of diet (and metabolism) on human δ15N we compiled a dataset of δ15N values of contemporary human food items from literature and experimental data summarizing more than 12,000 samples [1]. This data set allows to estimate the δ15N of “typical” diets consumed by individuals or populations. Accuracy and precision of estimated “theoretical” δ15N of human diets based on nutritional records and nutritional data sets were validated using experimental 24-hour diets. The data set was used to generate worldwide theoretical dietary δ15N values for different populations appraising potential geographical differences.

The effect of a controlled dietary change from terrestrial animal protein to marine products on human δ15N values was tested over a period of 28 days [2]. The subjects showed individual differences in incorporation rates of the isotopic signal into hair probably depending on metabolic turnover.