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Randomized Controlled Trial
. 2013 Feb;52(1):389-95.
doi: 10.1007/s00394-012-0328-2. Epub 2012 Mar 10.

Carbon and nitrogen isotopic ratios of urine and faeces as novel nutritional biomarkers of meat and fish intake

Gunter G C Kuhnle  1 , Annemiek M C P Joosen, Catherine J Kneale, Tamsin C O'Connell
Affiliations
Randomized Controlled Trial

Carbon and nitrogen isotopic ratios of urine and faeces as novel nutritional biomarkers of meat and fish intake

Gunter G C Kuhnle et al. Eur J Nutr. 2013 Feb.

Abstract

Purpose: Meat and fish consumption are associated with changes in the risk of chronic diseases. Intake is mainly assessed using self-reporting, as no true quantitative nutritional biomarker is available. The measurement of plasma fatty acids, often used as an alternative, is expensive and time-consuming. As meat and fish differ in their stable isotope ratios, δ(13)C and δ(15)N have been proposed as biomarkers. However, they have never been investigated in controlled human dietary intervention studies.

Objective: In a short-term feeding study, we investigated the suitability of δ(13)C and δ(15)N in blood, urine and faeces as biomarkers of meat and fish intake.

Methods: The dietary intervention study (n = 14) followed a randomised cross-over design with three eight-day dietary periods (meat, fish and half-meat-half-fish). In addition, 4 participants completed a vegetarian control period. At the end of each period, 24-h urine, fasting venous blood and faeces were collected and their δ(13)C and δ(15)N analysed.

Results: There was a significant difference between diets in isotope ratios in faeces and urine samples, but not in blood samples (Kruskal-Wallis test, p < 0.0001). In pairwise comparisons, δ(13)C and δ(15)N were significantly higher in urine and faecal samples following a fish diet when compared with all other diets, and significantly lower following a vegetarian diet. There was no significant difference in isotope ratio between meat and half-meat-half-fish diets for blood, urine or faecal samples.

Conclusions: The results of this study show that urinary and faecal δ(13)C and δ(15)N are suitable candidate biomarkers for short-term meat and fish intake.

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Figures

Fig. 1
Fig. 1
Isotope ratios (δ13C and δ15N) of intervention diets in faeces (dark grey), blood (medium) and urine (light grey). Dietary data is shown as median and inter-quartile range; data for blood, faecal samples and urine (except for vegetarian diet where individual results are shown) are shown as bagplot (50% of samples are within the grey area)
See this image and copyright information in PMC

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